diff --git a/README.md b/README.md
index 3612738..6080c68 100644
--- a/README.md
+++ b/README.md
@@ -1575,24 +1575,31 @@ reference with all required and optional fields.
 
 **Command dispatch table:**
 
-| Command   | Required Fields | Optional | Response Status |
-| --------- | --------------- | -------- | --------------- |
-| `PRIVMSG` | `to`, `body`    | `meta`   | 200 OK          |
-| `NOTICE`  | `to`, `body`    | `meta`   | 200 OK          |
-| `JOIN`    | `to`            |          | 200 OK          |
-| `PART`    | `to`            | `body`   | 200 OK          |
-| `NICK`    | `body`          |          | 200 OK          |
-| `PASS`    | `body`          |          | 200 OK          |
-| `TOPIC`   | `to`, `body`    |          | 200 OK          |
-| `MODE`    | `to`            |          | 200 OK          |
-| `NAMES`   | `to`            |          | 200 OK          |
-| `LIST`    |                 |          | 200 OK          |
-| `WHOIS`   | `to` or `body`  |          | 200 OK          |
-| `WHO`     | `to`            |          | 200 OK          |
-| `LUSERS`  |                 |          | 200 OK          |
-| `OPER`    | `body`          |          | 200 OK          |
-| `QUIT`    |                 | `body`   | 200 OK          |
-| `PING`    |                 |          | 200 OK          |
+| Command    | Required Fields | Optional | Response Status |
+| ---------- | --------------- | -------- | --------------- |
+| `PRIVMSG`  | `to`, `body`    | `meta`   | 200 OK          |
+| `NOTICE`   | `to`, `body`    | `meta`   | 200 OK          |
+| `JOIN`     | `to`            |          | 200 OK          |
+| `PART`     | `to`            | `body`   | 200 OK          |
+| `NICK`     | `body`          |          | 200 OK          |
+| `PASS`     | `body`          |          | 200 OK          |
+| `TOPIC`    | `to`, `body`    |          | 200 OK          |
+| `MODE`     | `to`            | `body`   | 200 OK          |
+| `NAMES`    | `to`            |          | 200 OK          |
+| `LIST`     |                 |          | 200 OK          |
+| `WHOIS`    | `to` or `body`  |          | 200 OK          |
+| `WHO`      | `to`            |          | 200 OK          |
+| `LUSERS`   |                 |          | 200 OK          |
+| `USERHOST` | `body`          |          | 200 OK          |
+| `VERSION`  |                 |          | 200 OK          |
+| `ADMIN`    |                 |          | 200 OK          |
+| `INFO`     |                 |          | 200 OK          |
+| `TIME`     |                 |          | 200 OK          |
+| `OPER`     | `body`          |          | 200 OK          |
+| `KILL`     | `body`          |          | 200 OK          |
+| `WALLOPS`  | `body`          |          | 200 OK          |
+| `QUIT`     |                 | `body`   | 200 OK          |
+| `PING`     |                 |          | 200 OK          |
 
 All IRC commands return HTTP 200 OK. IRC-level success and error responses are
 delivered as **numeric replies** through the message queue (see
@@ -1619,7 +1626,11 @@ auth cookies (401), and server errors (500).
 | 433     | ERR_NICKNAMEINUSE    | NICK target is taken                         |
 | 442     | ERR_NOTONCHANNEL     | Not a member of the target channel           |
 | 461     | ERR_NEEDMOREPARAMS   | Missing required fields (to, body)           |
+| 481     | ERR_NOPRIVILEGES     | KILL or WALLOPS by a non-operator            |
+| 483     | ERR_CANTKILLSERVER   | KILL of yourself                             |
 | 491     | ERR_NOOPERHOST       | Failed OPER authentication                   |
+| 501     | ERR_UMODEUNKNOWNFLAG | User MODE string not accepted                |
+| 502     | ERR_USERSDONTMATCH   | User MODE for a nick other than your own     |
 
 **IRC numeric success replies (delivered via message queue):**
 
@@ -1630,11 +1641,13 @@ auth cookies (401), and server errors (500).
 | 003     | RPL_CREATED       | Sent on session creation/login       |
 | 004     | RPL_MYINFO        | Sent on session creation/login       |
 | 005     | RPL_ISUPPORT      | Sent on session creation/login       |
-| 221     | RPL_UMODEIS       | In response to user MODE query       |
+| 221     | RPL_UMODEIS       | In response to user MODE             |
 | 251     | RPL_LUSERCLIENT   | On connect or LUSERS command         |
 | 252     | RPL_LUSEROP       | On connect or LUSERS command         |
 | 254     | RPL_LUSERCHANNELS | On connect or LUSERS command         |
 | 255     | RPL_LUSERME       | On connect or LUSERS command         |
+| 256–259 | RPL_ADMINME etc.  | ADMIN info                           |
+| 302     | RPL_USERHOST      | USERHOST reply                       |
 | 311     | RPL_WHOISUSER     | WHOIS user info                      |
 | 312     | RPL_WHOISSERVER   | WHOIS server info                    |
 | 313     | RPL_WHOISOPERATOR | WHOIS target is oper                 |
@@ -1642,6 +1655,10 @@ auth cookies (401), and server errors (500).
 | 318     | RPL_ENDOFWHOIS    | End of WHOIS list                    |
 | 319     | RPL_WHOISCHANNELS | WHOIS channels list                  |
 | 338     | RPL_WHOISACTUALLY | WHOIS client IP (oper-only)          |
+| 351     | RPL_VERSION       | VERSION reply                        |
+| 371     | RPL_INFO          | INFO line                            |
+| 374     | RPL_ENDOFINFO     | End of INFO                          |
+| 391     | RPL_TIME          | TIME reply                           |
 | 322     | RPL_LIST          | Channel in LIST response             |
 | 323     | RPL_LISTEND       | End of LIST                          |
 | 324     | RPL_CHANNELMODEIS | Channel mode query response          |
@@ -2384,13 +2401,13 @@ IRC_LISTEN_ADDR=
 
 ### Supported Commands
 
-| Category   | Commands                                                           |
-| ---------- | ------------------------------------------------------------------ |
-| Connection | `NICK`, `USER`, `PASS`, `QUIT`, `PING`/`PONG`, `CAP`               |
-| Channels   | `JOIN`, `PART`, `MODE`, `TOPIC`, `NAMES`, `LIST`, `KICK`, `INVITE` |
-| Messaging  | `PRIVMSG`, `NOTICE`                                                |
-| Info       | `WHO`, `WHOIS`, `LUSERS`, `MOTD`, `AWAY`                           |
-| Operator   | `OPER` (requires `NEOIRC_OPER_NAME` and `NEOIRC_OPER_PASSWORD`)    |
+| Category   | Commands                                                                                 |
+| ---------- | ---------------------------------------------------------------------------------------- |
+| Connection | `NICK`, `USER`, `PASS`, `QUIT`, `PING`/`PONG`, `CAP`                                     |
+| Channels   | `JOIN`, `PART`, `MODE`, `TOPIC`, `NAMES`, `LIST`, `KICK`, `INVITE`                       |
+| Messaging  | `PRIVMSG`, `NOTICE`                                                                      |
+| Info       | `WHO`, `WHOIS`, `LUSERS`, `MOTD`, `AWAY`, `USERHOST`, `VERSION`, `ADMIN`, `INFO`, `TIME` |
+| Operator   | `OPER`, `KILL`, `WALLOPS` (requires `NEOIRC_OPER_NAME` and `NEOIRC_OPER_PASSWORD`)       |
 
 ### Protocol Details
 
@@ -2406,6 +2423,15 @@ IRC_LISTEN_ADDR=
   operator status (`@`).
 - **Channel modes**: `+m` (moderated), `+t` (topic lock), `+o` (operator), `+v`
   (voice)
+- **User modes**: `+o` (operator, set only via `OPER`), `+w` (receives
+  `WALLOPS`). `MODE` for any nick other than your own is rejected with
+  `ERR_USERSDONTMATCH` (502), for both queries and changes. Nick comparison is
+  case-insensitive.
+- **KILL**: an operator's `KILL` broadcasts the victim's `QUIT` to its channel
+  peers, deletes its session, and then sends the victim a `KILL` and
+  `ERROR :Closing Link` before closing its socket. This applies to victims on
+  the IRC listener regardless of whether the `KILL` arrived over IRC or the HTTP
+  API.
 
 ### Bridge to HTTP API
 
@@ -2946,6 +2972,10 @@ guess is borne by the server (bcrypt), not the client.
       from additional devices via `POST /api/v1/login`
 - [x] **Cookie-based auth** — HttpOnly cookies replace Bearer tokens for all API
       authentication
+- [x] **Tier 3 utility commands** — `USERHOST` (302), `VERSION` (351), `ADMIN`
+      (256–259), `INFO` (371/374), `TIME` (391), `KILL` (operator-only forced
+      disconnect), `WALLOPS` (operator-only broadcast to `+w` users)
+- [x] **User mode +w** — receive `WALLOPS`, set with `MODE <nick> +w` / `-w`
 
 ### Future (1.0+)
 
diff --git a/internal/db/export_test.go b/internal/db/export_test.go
index 45c0435..f233380 100644
--- a/internal/db/export_test.go
+++ b/internal/db/export_test.go
@@ -58,3 +58,17 @@ func (database *Database) Close() error {
 
 	return nil
 }
+
+// ExecForTest runs a raw statement, such as a trigger that
+// makes a write fail.
+func (database *Database) ExecForTest(
+	ctx context.Context,
+	query string,
+) error {
+	_, err := database.conn.ExecContext(ctx, query)
+	if err != nil {
+		return fmt.Errorf("exec for test: %w", err)
+	}
+
+	return nil
+}
diff --git a/internal/db/queries.go b/internal/db/queries.go
index d840773..7b437df 100644
--- a/internal/db/queries.go
+++ b/internal/db/queries.go
@@ -7,6 +7,7 @@ import (
 	"database/sql"
 	"encoding/hex"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"strconv"
 	"strings"
@@ -2423,3 +2424,172 @@ func (database *Database) SetChannelUserLimit(
 
 	return nil
 }
+
+// SetSessionUserModes sets a session's wallops (+w) and
+// oper (+o) flags in one transaction, so that either both
+// changes are stored or neither is. A nil flag is left as
+// it is.
+func (database *Database) SetSessionUserModes(
+	ctx context.Context,
+	sessionID int64,
+	wallops *bool,
+	oper *bool,
+) error {
+	transaction, err := database.conn.BeginTx(ctx, nil)
+	if err != nil {
+		return fmt.Errorf("begin tx: %w", err)
+	}
+
+	if wallops != nil {
+		_, err = transaction.ExecContext(
+			ctx,
+			`UPDATE sessions SET is_wallops = ? WHERE id = ?`,
+			boolToInt(*wallops), sessionID,
+		)
+		if err != nil {
+			_ = transaction.Rollback()
+
+			return fmt.Errorf("set session wallops: %w", err)
+		}
+	}
+
+	if oper != nil {
+		_, err = transaction.ExecContext(
+			ctx,
+			`UPDATE sessions SET is_oper = ? WHERE id = ?`,
+			boolToInt(*oper), sessionID,
+		)
+		if err != nil {
+			_ = transaction.Rollback()
+
+			return fmt.Errorf("set session oper: %w", err)
+		}
+	}
+
+	err = transaction.Commit()
+	if err != nil {
+		return fmt.Errorf("commit user modes: %w", err)
+	}
+
+	return nil
+}
+
+// boolToInt returns the 0 or 1 that the schema stores for a
+// boolean.
+func boolToInt(value bool) int {
+	if value {
+		return 1
+	}
+
+	return 0
+}
+
+// IsSessionWallops returns whether the session has the
+// wallops (+w) usermode set.
+func (database *Database) IsSessionWallops(
+	ctx context.Context,
+	sessionID int64,
+) (bool, error) {
+	var isWallops int
+
+	err := database.conn.QueryRowContext(
+		ctx,
+		`SELECT is_wallops FROM sessions WHERE id = ?`,
+		sessionID,
+	).Scan(&isWallops)
+	if err != nil {
+		return false, fmt.Errorf(
+			"check session wallops: %w", err,
+		)
+	}
+
+	return isWallops != 0, nil
+}
+
+// GetWallopsSessionIDs returns all session IDs that have
+// the wallops (+w) usermode set.
+func (database *Database) GetWallopsSessionIDs(
+	ctx context.Context,
+) ([]int64, error) {
+	rows, err := database.conn.QueryContext(
+		ctx,
+		`SELECT id FROM sessions WHERE is_wallops = 1`,
+	)
+	if err != nil {
+		return nil, fmt.Errorf(
+			"get wallops sessions: %w", err,
+		)
+	}
+
+	defer func() { _ = rows.Close() }()
+
+	var ids []int64
+
+	for rows.Next() {
+		var sessionID int64
+
+		err = rows.Scan(&sessionID)
+		if err != nil {
+			return nil, fmt.Errorf(
+				"scan wallops session: %w", err,
+			)
+		}
+
+		ids = append(ids, sessionID)
+	}
+
+	err = rows.Err()
+	if err != nil {
+		return nil, fmt.Errorf(
+			"iterate wallops sessions: %w", err,
+		)
+	}
+
+	return ids, nil
+}
+
+// UserhostInfo holds the data needed for RPL_USERHOST.
+type UserhostInfo struct {
+	Nick        string
+	Username    string
+	Hostname    string
+	IsOper      bool
+	AwayMessage string
+}
+
+// GetUserhostInfo returns USERHOST info for the given
+// nicks. Nicks with no session are left out.
+func (database *Database) GetUserhostInfo(
+	ctx context.Context,
+	nicks []string,
+) ([]UserhostInfo, error) {
+	results := make([]UserhostInfo, 0, len(nicks))
+
+	for _, nick := range nicks {
+		var info UserhostInfo
+
+		err := database.conn.QueryRowContext(
+			ctx,
+			`SELECT nick, username, hostname,
+			        is_oper, away_message
+			 FROM sessions WHERE nick = ?`,
+			nick,
+		).Scan(
+			&info.Nick, &info.Username, &info.Hostname,
+			&info.IsOper, &info.AwayMessage,
+		)
+		if errors.Is(err, sql.ErrNoRows) {
+			continue
+		}
+
+		if err != nil {
+			return nil, fmt.Errorf(
+				"userhost lookup %q: %w", nick, err,
+			)
+		}
+
+		results = append(results, info)
+	}
+
+	return results, nil
+}
diff --git a/internal/db/queries_test.go b/internal/db/queries_test.go
index 9c201d2..d5467a9 100644
--- a/internal/db/queries_test.go
+++ b/internal/db/queries_test.go
@@ -1491,3 +1491,119 @@ func TestChannelUserLimit(t *testing.T) {
 		t.Fatalf("expected 0, got %d", limit)
 	}
 }
+
+// TestSetSessionUserModesIsAtomic makes the is_oper write
+// fail after the is_wallops write has run, and checks that
+// the wallops change was rolled back.
+func TestSetSessionUserModesIsAtomic(t *testing.T) {
+	t.Parallel()
+
+	database := setupTestDB(t)
+	ctx := t.Context()
+
+	sessionID, _, _, err := database.CreateSession(
+		ctx, "alice", "", "", "",
+	)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	err = database.ExecForTest(ctx,
+		`CREATE TRIGGER reject_oper
+		 BEFORE UPDATE OF is_oper ON sessions
+		 BEGIN SELECT RAISE(ABORT, 'oper write rejected');
+		 END`,
+	)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	wallops := true
+	oper := false
+
+	err = database.SetSessionUserModes(
+		ctx, sessionID, &wallops, &oper,
+	)
+	if err == nil {
+		t.Fatal("expected the rejected oper write to fail")
+	}
+
+	gotWallops, err := database.IsSessionWallops(
+		ctx, sessionID,
+	)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if gotWallops {
+		t.Error("wallops was stored although the change failed")
+	}
+}
+
+// TestSetSessionUserModesAppliesBoth checks that both flags
+// are written, and that a nil flag is left as it is.
+func TestSetSessionUserModesAppliesBoth(t *testing.T) {
+	t.Parallel()
+
+	database := setupTestDB(t)
+	ctx := t.Context()
+
+	sessionID, _, _, err := database.CreateSession(
+		ctx, "alice", "", "", "",
+	)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	err = database.SetSessionOper(ctx, sessionID, true)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	wallops := true
+	oper := false
+
+	err = database.SetSessionUserModes(
+		ctx, sessionID, &wallops, &oper,
+	)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	gotWallops, err := database.IsSessionWallops(
+		ctx, sessionID,
+	)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	gotOper, err := database.IsSessionOper(ctx, sessionID)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if !gotWallops || gotOper {
+		t.Errorf(
+			"want wallops=true oper=false, got %v/%v",
+			gotWallops, gotOper,
+		)
+	}
+
+	err = database.SetSessionUserModes(
+		ctx, sessionID, nil, nil,
+	)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	gotWallops, err = database.IsSessionWallops(
+		ctx, sessionID,
+	)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if !gotWallops {
+		t.Error("a nil wallops flag cleared wallops")
+	}
+}
diff --git a/internal/db/schema/001_initial.sql b/internal/db/schema/001_initial.sql
index e53c48b..1a1b27f 100644
--- a/internal/db/schema/001_initial.sql
+++ b/internal/db/schema/001_initial.sql
@@ -10,6 +10,7 @@ CREATE TABLE IF NOT EXISTS sessions (
     hostname TEXT NOT NULL DEFAULT '',
     ip TEXT NOT NULL DEFAULT '',
     is_oper INTEGER NOT NULL DEFAULT 0,
+    is_wallops INTEGER NOT NULL DEFAULT 0,
     password_hash TEXT NOT NULL DEFAULT '',
     signing_key TEXT NOT NULL DEFAULT '',
     away_message TEXT NOT NULL DEFAULT '',
diff --git a/internal/handlers/api.go b/internal/handlers/api.go
index 3da43f3..3d98775 100644
--- a/internal/handlers/api.go
+++ b/internal/handlers/api.go
@@ -1015,10 +1015,10 @@ func (hdlr *Handlers) dispatchCommand(
 		hdlr.handleQuit(
 			writer, request, sessionID, nick, body,
 		)
-	case irc.CmdOper:
-		hdlr.handleOper(
+	case irc.CmdOper, irc.CmdKill, irc.CmdWallops:
+		hdlr.dispatchOperCommand(
 			writer, request,
-			sessionID, clientID, nick, bodyLines,
+			sessionID, clientID, nick, command, bodyLines,
 		)
 	case irc.CmdMotd, irc.CmdPing:
 		hdlr.dispatchInfoCommand(
@@ -1075,6 +1075,27 @@ func (hdlr *Handlers) dispatchQueryCommand(
 			writer, request,
 			sessionID, clientID, nick,
 		)
+	case irc.CmdUserhost:
+		hdlr.handleUserhost(
+			writer, request,
+			sessionID, clientID, nick, bodyLines,
+		)
+	case irc.CmdVersion:
+		hdlr.handleVersion(
+			writer, request, sessionID, clientID, nick,
+		)
+	case irc.CmdAdmin:
+		hdlr.handleAdmin(
+			writer, request, sessionID, clientID, nick,
+		)
+	case irc.CmdInfo:
+		hdlr.handleInfo(
+			writer, request, sessionID, clientID, nick,
+		)
+	case irc.CmdTime:
+		hdlr.handleTime(
+			writer, request, sessionID, clientID, nick,
+		)
 	default:
 		hdlr.enqueueNumeric(
 			request.Context(), clientID,
@@ -1951,15 +1972,11 @@ func (hdlr *Handlers) handleMode(
 
 	channel := target
 	if !strings.HasPrefix(channel, "#") {
-		// User mode query — return empty modes.
-		hdlr.enqueueNumeric(
-			request.Context(), clientID,
-			irc.RplUmodeIs, nick, nil, "+",
+		hdlr.handleUserMode(
+			writer, request,
+			sessionID, clientID, nick, target,
+			bodyLines,
 		)
-		hdlr.broker.Notify(sessionID)
-		hdlr.respondJSON(writer, request,
-			map[string]string{statusKey: "ok"},
-			http.StatusOK)
 
 		return
 	}
diff --git a/internal/handlers/api_test.go b/internal/handlers/api_test.go
index 594ef40..4fff74e 100644
--- a/internal/handlers/api_test.go
+++ b/internal/handlers/api_test.go
@@ -293,6 +293,7 @@ func newTestHandlers(
 		Config:   cfg,
 		Database: database,
 		Broker:   brk,
+		Globals:  globs,
 	})
 
 	hdlr, err := handlers.New(lifecycle, handlers.Params{ //nolint:exhaustruct
diff --git a/internal/handlers/utility.go b/internal/handlers/utility.go
new file mode 100644
index 0000000..0ae2242
--- /dev/null
+++ b/internal/handlers/utility.go
@@ -0,0 +1,307 @@
+package handlers
+
+import (
+	"net/http"
+	"strings"
+	"time"
+
+	"sneak.berlin/go/neoirc/pkg/irc"
+)
+
+// dispatchOperCommand routes the server operator commands
+// OPER, KILL and WALLOPS to their handlers.
+func (hdlr *Handlers) dispatchOperCommand(
+	writer http.ResponseWriter,
+	request *http.Request,
+	sessionID, clientID int64,
+	nick, command string,
+	bodyLines func() []string,
+) {
+	switch command {
+	case irc.CmdOper:
+		hdlr.handleOper(
+			writer, request,
+			sessionID, clientID, nick, bodyLines,
+		)
+	case irc.CmdKill:
+		hdlr.handleKill(
+			writer, request,
+			sessionID, clientID, nick, bodyLines,
+		)
+	case irc.CmdWallops:
+		hdlr.handleWallops(
+			writer, request,
+			sessionID, clientID, nick, bodyLines,
+		)
+	}
+}
+
+// handleUserhost handles USERHOST: user@host for each of
+// up to five nicks given in the body.
+func (hdlr *Handlers) handleUserhost(
+	writer http.ResponseWriter,
+	request *http.Request,
+	sessionID, clientID int64,
+	nick string,
+	bodyLines func() []string,
+) {
+	lines := bodyLines()
+	if len(lines) == 0 {
+		hdlr.respondIRCError(
+			writer, request, clientID, sessionID,
+			irc.ErrNeedMoreParams, nick,
+			[]string{irc.CmdUserhost},
+			"Not enough parameters",
+		)
+
+		return
+	}
+
+	reply, err := hdlr.svc.UserhostReply(
+		request.Context(), lines, hdlr.serverName(),
+	)
+	if hdlr.handleServiceError(
+		writer, request, clientID, sessionID, nick, err,
+	) {
+		return
+	}
+
+	hdlr.enqueueNumeric(
+		request.Context(), clientID,
+		irc.RplUserHost, nick, nil, reply,
+	)
+	hdlr.broker.Notify(sessionID)
+	hdlr.respondJSON(writer, request,
+		map[string]string{statusKey: "ok"},
+		http.StatusOK)
+}
+
+// handleVersion handles VERSION.
+func (hdlr *Handlers) handleVersion(
+	writer http.ResponseWriter,
+	request *http.Request,
+	sessionID, clientID int64,
+	nick string,
+) {
+	hdlr.enqueueNumeric(
+		request.Context(), clientID, irc.RplVersion, nick,
+		[]string{
+			hdlr.svc.ServerVersion() + ".",
+			hdlr.serverName(),
+		},
+		"",
+	)
+	hdlr.broker.Notify(sessionID)
+	hdlr.respondJSON(writer, request,
+		map[string]string{statusKey: "ok"},
+		http.StatusOK)
+}
+
+// handleAdmin handles ADMIN.
+func (hdlr *Handlers) handleAdmin(
+	writer http.ResponseWriter,
+	request *http.Request,
+	sessionID, clientID int64,
+	nick string,
+) {
+	ctx := request.Context()
+	srvName := hdlr.serverName()
+
+	hdlr.enqueueNumeric(
+		ctx, clientID, irc.RplAdminMe, nick,
+		[]string{srvName}, "Administrative info",
+	)
+	hdlr.enqueueNumeric(
+		ctx, clientID, irc.RplAdminLoc1, nick, nil,
+		"neoirc server",
+	)
+	hdlr.enqueueNumeric(
+		ctx, clientID, irc.RplAdminLoc2, nick, nil,
+		"IRC over HTTP",
+	)
+	hdlr.enqueueNumeric(
+		ctx, clientID, irc.RplAdminEmail, nick, nil,
+		"admin@"+srvName,
+	)
+	hdlr.broker.Notify(sessionID)
+	hdlr.respondJSON(writer, request,
+		map[string]string{statusKey: "ok"},
+		http.StatusOK)
+}
+
+// handleInfo handles INFO.
+func (hdlr *Handlers) handleInfo(
+	writer http.ResponseWriter,
+	request *http.Request,
+	sessionID, clientID int64,
+	nick string,
+) {
+	ctx := request.Context()
+
+	for _, line := range hdlr.svc.InfoLines() {
+		hdlr.enqueueNumeric(
+			ctx, clientID, irc.RplInfo, nick, nil, line,
+		)
+	}
+
+	hdlr.enqueueNumeric(
+		ctx, clientID, irc.RplEndOfInfo, nick, nil,
+		"End of /INFO list",
+	)
+	hdlr.broker.Notify(sessionID)
+	hdlr.respondJSON(writer, request,
+		map[string]string{statusKey: "ok"},
+		http.StatusOK)
+}
+
+// handleTime handles TIME: the server's local time.
+func (hdlr *Handlers) handleTime(
+	writer http.ResponseWriter,
+	request *http.Request,
+	sessionID, clientID int64,
+	nick string,
+) {
+	hdlr.enqueueNumeric(
+		request.Context(), clientID, irc.RplTime, nick,
+		[]string{hdlr.serverName()},
+		time.Now().Format(time.RFC1123),
+	)
+	hdlr.broker.Notify(sessionID)
+	hdlr.respondJSON(writer, request,
+		map[string]string{statusKey: "ok"},
+		http.StatusOK)
+}
+
+// handleKill handles KILL: the body is the target nick and
+// an optional reason.
+func (hdlr *Handlers) handleKill(
+	writer http.ResponseWriter,
+	request *http.Request,
+	sessionID, clientID int64,
+	nick string,
+	bodyLines func() []string,
+) {
+	lines := bodyLines()
+
+	targetNick := ""
+	if len(lines) > 0 {
+		targetNick = strings.TrimSpace(lines[0])
+	}
+
+	if targetNick == "" {
+		hdlr.respondIRCError(
+			writer, request, clientID, sessionID,
+			irc.ErrNeedMoreParams, nick,
+			[]string{irc.CmdKill},
+			"Not enough parameters",
+		)
+
+		return
+	}
+
+	reason := "KILLed"
+	if len(lines) > 1 {
+		reason = lines[1]
+	}
+
+	err := hdlr.svc.KillUser(
+		request.Context(), sessionID, nick,
+		targetNick, reason,
+	)
+	if hdlr.handleServiceError(
+		writer, request, clientID, sessionID, nick, err,
+	) {
+		return
+	}
+
+	hdlr.respondJSON(writer, request,
+		map[string]string{statusKey: "ok"},
+		http.StatusOK)
+}
+
+// handleWallops handles WALLOPS: the body is the message.
+func (hdlr *Handlers) handleWallops(
+	writer http.ResponseWriter,
+	request *http.Request,
+	sessionID, clientID int64,
+	nick string,
+	bodyLines func() []string,
+) {
+	lines := bodyLines()
+	if len(lines) == 0 {
+		hdlr.respondIRCError(
+			writer, request, clientID, sessionID,
+			irc.ErrNeedMoreParams, nick,
+			[]string{irc.CmdWallops},
+			"Not enough parameters",
+		)
+
+		return
+	}
+
+	err := hdlr.svc.SendWallops(
+		request.Context(), sessionID, nick,
+		strings.Join(lines, " "),
+	)
+	if hdlr.handleServiceError(
+		writer, request, clientID, sessionID, nick, err,
+	) {
+		return
+	}
+
+	hdlr.respondJSON(writer, request,
+		map[string]string{statusKey: "ok"},
+		http.StatusOK)
+}
+
+// handleUserMode handles MODE for a nick: a query when the
+// body is empty, otherwise a change by the mode string in
+// the body. Only the caller's own nick, in any letter case,
+// is allowed.
+func (hdlr *Handlers) handleUserMode(
+	writer http.ResponseWriter,
+	request *http.Request,
+	sessionID, clientID int64,
+	nick, target string,
+	bodyLines func() []string,
+) {
+	if !strings.EqualFold(target, nick) {
+		hdlr.respondIRCError(
+			writer, request, clientID, sessionID,
+			irc.ErrUsersDoNotMatch, nick, nil,
+			"Can't change mode for other users",
+		)
+
+		return
+	}
+
+	ctx := request.Context()
+
+	var (
+		modes string
+		err   error
+	)
+
+	lines := bodyLines()
+	if len(lines) > 0 {
+		modes, err = hdlr.svc.ApplyUserMode(
+			ctx, sessionID, lines[0],
+		)
+	} else {
+		modes, err = hdlr.svc.QueryUserMode(ctx, sessionID)
+	}
+
+	if hdlr.handleServiceError(
+		writer, request, clientID, sessionID, nick, err,
+	) {
+		return
+	}
+
+	hdlr.enqueueNumeric(
+		ctx, clientID, irc.RplUmodeIs, nick, nil, modes,
+	)
+	hdlr.broker.Notify(sessionID)
+	hdlr.respondJSON(writer, request,
+		map[string]string{statusKey: "ok"},
+		http.StatusOK)
+}
diff --git a/internal/handlers/utility_test.go b/internal/handlers/utility_test.go
new file mode 100644
index 0000000..cb76075
--- /dev/null
+++ b/internal/handlers/utility_test.go
@@ -0,0 +1,324 @@
+//nolint:paralleltest // global viper, as in api_test.go
+package handlers_test
+
+import (
+	"net/http"
+	"strings"
+	"testing"
+
+	"sneak.berlin/go/neoirc/pkg/irc"
+)
+
+// Each test starts one server and reuses it for all its
+// checks, and makes as few requests as it can: servers,
+// sessions and requests are what makes this package's tests
+// slow.
+
+// sendAndPoll sends cmd from the session token and returns
+// the messages after lastID that the session has been sent,
+// and the ID of the last of them.
+func sendAndPoll(
+	tserver *testServer,
+	token string,
+	lastID int64,
+	cmd map[string]any,
+) ([]map[string]any, int64) {
+	tserver.t.Helper()
+
+	tserver.sendCommand(token, cmd)
+
+	return tserver.pollMessages(token, lastID)
+}
+
+// newOperSession creates a session for nick, makes it a
+// server operator, and returns its token and the ID of the
+// last message it has been sent.
+func newOperSession(
+	tserver *testServer, nick string,
+) (string, int64) {
+	tserver.t.Helper()
+
+	token := tserver.createSession(nick)
+
+	_, lastID := sendAndPoll(tserver, token, 0, map[string]any{
+		commandKey: irc.CmdOper,
+		bodyKey:    []string{testOperName, testOperPassword},
+	})
+
+	return token, lastID
+}
+
+// numericBody returns the first body line of the message in
+// msgs with the given numeric, and fails the test if there
+// is none.
+func numericBody(
+	t *testing.T, msgs []map[string]any, numeric string,
+) string {
+	t.Helper()
+
+	msg := findNumericWithParams(msgs, numeric)
+	if msg == nil {
+		t.Fatalf("expected numeric %s, got %v", numeric, msgs)
+	}
+
+	lines, _ := msg[bodyKey].([]any)
+	if len(lines) == 0 {
+		return ""
+	}
+
+	line, _ := lines[0].(string)
+
+	return line
+}
+
+func TestUserhost(t *testing.T) {
+	tserver := newTestServer(t)
+
+	token := tserver.createSession("alice")
+	tserver.createSession("bob")
+
+	_, lastID := tserver.pollMessages(token, 0)
+
+	msgs, lastID := sendAndPoll(tserver, token, lastID, map[string]any{
+		commandKey: irc.CmdUserhost,
+		bodyKey:    []string{"alice", "bob"},
+	})
+
+	body := numericBody(t, msgs, "302")
+	if !strings.HasPrefix(body, "alice=+alice@") ||
+		!strings.Contains(body, " bob=+bob@") {
+		t.Errorf("expected alice and bob, got %q", body)
+	}
+
+	msgs, _ = sendAndPoll(tserver, token, lastID, map[string]any{
+		commandKey: irc.CmdUserhost,
+	})
+	if !findNumeric(msgs, "461") {
+		t.Errorf("expected ERR_NEEDMOREPARAMS (461), got %v", msgs)
+	}
+}
+
+func TestVersionAdminInfoTime(t *testing.T) {
+	tserver := newTestServer(t)
+
+	token := tserver.createSession("frank")
+	_, lastID := tserver.pollMessages(token, 0)
+
+	msgs, lastID := sendAndPoll(tserver, token, lastID, map[string]any{
+		commandKey: irc.CmdVersion,
+	})
+
+	params := getNumericParams(findNumericWithParams(msgs, "351"))
+	if len(params) == 0 || params[0] != "neoirc-test-test." {
+		t.Errorf("expected RPL_VERSION neoirc-test-test., got %v", msgs)
+	}
+
+	for _, check := range []struct {
+		command  string
+		numerics []string
+	}{
+		{irc.CmdAdmin, []string{"256", "257", "258", "259"}},
+		{irc.CmdInfo, []string{"371", "374"}},
+		{irc.CmdTime, []string{"391"}},
+	} {
+		msgs, lastID = sendAndPoll(tserver, token, lastID, map[string]any{
+			commandKey: check.command,
+		})
+
+		for _, numeric := range check.numerics {
+			if !findNumeric(msgs, numeric) {
+				t.Errorf(
+					"%s: expected %s, got %v",
+					check.command, numeric, msgs,
+				)
+			}
+		}
+	}
+}
+
+func TestKill(t *testing.T) {
+	tserver := newTestServerWithOper(t)
+
+	victimToken := tserver.createSession("victim")
+	observerToken := tserver.createSession("observer")
+	notOperToken := tserver.createSession("notoper")
+	operToken, operLastID := newOperSession(tserver, "killer")
+
+	for _, token := range []string{victimToken, observerToken} {
+		tserver.sendCommand(token, map[string]any{
+			commandKey: joinCmd,
+			toKey:      "#killtest",
+		})
+	}
+
+	_, notOperLastID := tserver.pollMessages(notOperToken, 0)
+
+	msgs, _ := sendAndPoll(tserver, notOperToken, notOperLastID, map[string]any{
+		commandKey: irc.CmdKill,
+		bodyKey:    []string{"victim"},
+	})
+	if !findNumeric(msgs, "481") {
+		t.Errorf("expected ERR_NOPRIVILEGES (481), got %v", msgs)
+	}
+
+	for _, check := range []struct {
+		numeric string
+		body    []string
+	}{
+		{"461", []string{}},
+		{"401", []string{"ghost"}},
+		{"483", []string{"killer"}},
+	} {
+		msgs, operLastID = sendAndPoll(tserver, operToken, operLastID, map[string]any{
+			commandKey: irc.CmdKill,
+			bodyKey:    check.body,
+		})
+		if !findNumeric(msgs, check.numeric) {
+			t.Errorf(
+				"KILL %v: expected %s, got %v",
+				check.body, check.numeric, msgs,
+			)
+		}
+	}
+
+	_, observerLastID := tserver.pollMessages(observerToken, 0)
+
+	status, result := tserver.sendCommand(operToken, map[string]any{
+		commandKey: irc.CmdKill,
+		bodyKey:    []string{"victim", "go away"},
+	})
+	if status != http.StatusOK {
+		t.Fatalf("expected 200, got %d: %v", status, result)
+	}
+
+	msgs, _ = tserver.pollMessages(observerToken, observerLastID)
+	if !findMessage(msgs, irc.CmdQuit, "victim") {
+		t.Errorf("expected the observer to see QUIT, got %v", msgs)
+	}
+
+	status, _ = tserver.getState(victimToken)
+	if status != http.StatusUnauthorized {
+		t.Errorf("expected the victim's session gone, got %d", status)
+	}
+}
+
+func TestWallops(t *testing.T) {
+	tserver := newTestServerWithOper(t)
+
+	receiverToken := tserver.createSession("receiver")
+	plainToken := tserver.createSession("plain")
+	operToken, operLastID := newOperSession(tserver, "walloper")
+
+	_, receiverLastID := sendAndPoll(tserver, receiverToken, 0, map[string]any{
+		commandKey: modeCmd,
+		toKey:      "receiver",
+		bodyKey:    []string{"+w"},
+	})
+	_, plainLastID := tserver.pollMessages(plainToken, 0)
+
+	msgs, plainLastID := sendAndPoll(tserver, plainToken, plainLastID, map[string]any{
+		commandKey: irc.CmdWallops,
+		bodyKey:    []string{"not allowed"},
+	})
+	if !findNumeric(msgs, "481") {
+		t.Errorf("expected ERR_NOPRIVILEGES (481), got %v", msgs)
+	}
+
+	msgs, _ = sendAndPoll(tserver, operToken, operLastID, map[string]any{
+		commandKey: irc.CmdWallops,
+	})
+	if !findNumeric(msgs, "461") {
+		t.Errorf("expected ERR_NEEDMOREPARAMS (461), got %v", msgs)
+	}
+
+	tserver.sendCommand(operToken, map[string]any{
+		commandKey: irc.CmdWallops,
+		bodyKey:    []string{"server going down"},
+	})
+
+	msgs, _ = tserver.pollMessages(receiverToken, receiverLastID)
+	if !findMessage(msgs, irc.CmdWallops, "walloper") {
+		t.Errorf("expected WALLOPS for the +w user, got %v", msgs)
+	}
+
+	msgs, _ = tserver.pollMessages(plainToken, plainLastID)
+	if findMessage(msgs, irc.CmdWallops, "walloper") {
+		t.Errorf("WALLOPS reached a user without +w: %v", msgs)
+	}
+}
+
+func TestUserMode(t *testing.T) {
+	const (
+		nick  = "alice"
+		other = "other"
+	)
+
+	tserver := newTestServerWithOper(t)
+
+	token := tserver.createSession(nick)
+	otherToken := tserver.createSession(other)
+	operToken, operLastID := newOperSession(tserver, "deoper")
+
+	// mode sends MODE for target from token, with modeStr
+	// unless it is empty, and returns the session's next
+	// messages.
+	mode := func(
+		token string, lastID int64, target, modeStr string,
+	) ([]map[string]any, int64) {
+		cmd := map[string]any{commandKey: modeCmd, toKey: target}
+		if modeStr != "" {
+			cmd[bodyKey] = []string{modeStr}
+		}
+
+		return sendAndPoll(tserver, token, lastID, cmd)
+	}
+
+	_, otherLastID := mode(otherToken, 0, other, "+w")
+	_, lastID := tserver.pollMessages(token, 0)
+
+	for _, check := range []struct {
+		target, modeStr, numeric, modes string
+	}{
+		{nick, "+w", "221", "+w"},
+		{nick, "", "221", "+w"},
+		{strings.ToUpper(nick), "-w", "221", "+"},
+		{nick, "+z", "501", ""},
+		{other, "", "502", ""},
+		{other, "-w", "502", ""},
+	} {
+		var msgs []map[string]any
+
+		msgs, lastID = mode(token, lastID, check.target, check.modeStr)
+
+		if check.numeric != "221" {
+			if !findNumeric(msgs, check.numeric) ||
+				findNumeric(msgs, "221") {
+				t.Errorf(
+					"MODE %s %s: expected only %s, got %v",
+					check.target, check.modeStr,
+					check.numeric, msgs,
+				)
+			}
+
+			continue
+		}
+
+		got := numericBody(t, msgs, "221")
+		if got != check.modes {
+			t.Errorf(
+				"MODE %s %s: expected %q, got %q",
+				check.target, check.modeStr, check.modes, got,
+			)
+		}
+	}
+
+	msgs, _ := mode(otherToken, otherLastID, other, "")
+	if got := numericBody(t, msgs, "221"); got != "+w" {
+		t.Errorf("%s's modes changed to %q", other, got)
+	}
+
+	msgs, _ = mode(operToken, operLastID, "deoper", "-o")
+	if got := numericBody(t, msgs, "221"); got != "+" {
+		t.Errorf("after -o: expected +, got %q", got)
+	}
+}
diff --git a/internal/ircserver/commands.go b/internal/ircserver/commands.go
index e6c3356..99785ae 100644
--- a/internal/ircserver/commands.go
+++ b/internal/ircserver/commands.go
@@ -13,7 +13,7 @@ import (
 )
 
 // sendIRCError maps a service.IRCError to an IRC numeric
-// reply on the wire.
+// reply on the wire, and logs any other error.
 func (c *Conn) sendIRCError(err error) {
 	var ircErr *service.IRCError
 	if errors.As(err, &ircErr) {
@@ -21,7 +21,11 @@ func (c *Conn) sendIRCError(err error) {
 		args = append(args, ircErr.Params...)
 		args = append(args, ircErr.Message)
 		c.sendNumeric(ircErr.Code, args...)
+
+		return
 	}
+
+	c.log.Error("command failed", "error", err)
 }
 
 // handleCAP silently acknowledges CAP negotiation.
@@ -345,7 +349,10 @@ func (c *Conn) handleQuit(msg *Message) {
 
 	c.send("ERROR :Closing Link: " + c.hostname +
 		" (Quit: " + reason + ")")
+
+	c.mu.Lock()
 	c.closed = true
+	c.mu.Unlock()
 }
 
 // handleTopic gets or sets a channel topic via the shared
@@ -427,7 +434,7 @@ func (c *Conn) handleMode(
 	if strings.HasPrefix(target, "#") {
 		c.handleChannelMode(ctx, msg)
 	} else {
-		c.handleUserMode(msg)
+		c.handleUserMode(ctx, msg)
 	}
 }
 
@@ -686,11 +693,14 @@ func (c *Conn) applyChannelModes(
 	}
 }
 
-// handleUserMode handles MODE for users.
-func (c *Conn) handleUserMode(msg *Message) {
-	target := msg.Params[0]
-
-	if !strings.EqualFold(target, c.nick) {
+// handleUserMode handles MODE for a nick: a query without a
+// mode string, otherwise a change. Only the client's own
+// nick, in any letter case, is allowed.
+func (c *Conn) handleUserMode(
+	ctx context.Context,
+	msg *Message,
+) {
+	if !strings.EqualFold(msg.Params[0], c.currentNick()) {
 		c.sendNumeric(
 			irc.ErrUsersDoNotMatch,
 			"Can't change mode for other users",
@@ -699,8 +709,26 @@ func (c *Conn) handleUserMode(msg *Message) {
 		return
 	}
 
-	// We don't support user modes beyond the basics.
-	c.sendNumeric(irc.RplUmodeIs, "+")
+	var (
+		modes string
+		err   error
+	)
+
+	if len(msg.Params) == 1 {
+		modes, err = c.svc.QueryUserMode(ctx, c.sessionID)
+	} else {
+		modes, err = c.svc.ApplyUserMode(
+			ctx, c.sessionID, msg.Params[1],
+		)
+	}
+
+	if err != nil {
+		c.sendIRCError(err)
+
+		return
+	}
+
+	c.sendNumeric(irc.RplUmodeIs, modes)
 }
 
 // handleNames replies with channel member list.
@@ -1248,47 +1276,114 @@ func (c *Conn) handleInvite(
 	)
 }
 
-// handleUserhost replies with USERHOST info.
+// handleUserhost replies with user@host for each of up to
+// five nicks.
 func (c *Conn) handleUserhost(
 	ctx context.Context,
 	msg *Message,
 ) {
 	if len(msg.Params) < 1 {
+		c.sendNumeric(
+			irc.ErrNeedMoreParams,
+			irc.CmdUserhost, "Not enough parameters",
+		)
+
 		return
 	}
 
-	replies := make([]string, 0, len(msg.Params))
+	reply, err := c.svc.UserhostReply(
+		ctx, msg.Params, c.serverSfx,
+	)
+	if err != nil {
+		c.sendIRCError(err)
 
-	for _, nick := range msg.Params {
-		sid, err := c.database.GetSessionByNick(ctx, nick)
-		if err != nil {
-			continue
-		}
-
-		hostInfo, _ := c.database.GetSessionHostInfo(
-			ctx, sid,
-		)
-
-		host := "*"
-		if hostInfo != nil {
-			host = hostInfo.Hostname
-		}
-
-		isOper, _ := c.database.IsSessionOper(ctx, sid)
-
-		operStar := ""
-		if isOper {
-			operStar = "*"
-		}
-
-		replies = append(
-			replies,
-			nick+operStar+"=+"+nick+"@"+host,
-		)
+		return
 	}
 
+	c.sendNumeric(irc.RplUserHost, reply)
+}
+
+// handleVersion replies with the server version.
+func (c *Conn) handleVersion() {
 	c.sendNumeric(
-		irc.RplUserHost,
-		strings.Join(replies, " "),
+		irc.RplVersion,
+		c.svc.ServerVersion()+".", c.serverSfx, "",
 	)
 }
+
+// handleAdmin replies with the server's admin info.
+func (c *Conn) handleAdmin() {
+	c.sendNumeric(
+		irc.RplAdminMe, c.serverSfx, "Administrative info",
+	)
+	c.sendNumeric(irc.RplAdminLoc1, "neoirc server")
+	c.sendNumeric(irc.RplAdminLoc2, "IRC over HTTP")
+	c.sendNumeric(irc.RplAdminEmail, "admin@"+c.serverSfx)
+}
+
+// handleInfo replies with the server's software info.
+func (c *Conn) handleInfo() {
+	for _, line := range c.svc.InfoLines() {
+		c.sendNumeric(irc.RplInfo, line)
+	}
+
+	c.sendNumeric(irc.RplEndOfInfo, "End of /INFO list")
+}
+
+// handleTime replies with the server's local time.
+func (c *Conn) handleTime() {
+	c.sendNumeric(
+		irc.RplTime,
+		c.serverSfx, time.Now().Format(time.RFC1123),
+	)
+}
+
+// handleKill handles KILL <nick> [<reason>].
+func (c *Conn) handleKill(
+	ctx context.Context,
+	msg *Message,
+) {
+	if len(msg.Params) < 1 {
+		c.sendNumeric(
+			irc.ErrNeedMoreParams,
+			irc.CmdKill, "Not enough parameters",
+		)
+
+		return
+	}
+
+	reason := "KILLed"
+	if len(msg.Params) > 1 {
+		reason = msg.Params[1]
+	}
+
+	err := c.svc.KillUser(
+		ctx, c.sessionID, c.currentNick(),
+		msg.Params[0], reason,
+	)
+	if err != nil {
+		c.sendIRCError(err)
+	}
+}
+
+// handleWallops handles WALLOPS <message>.
+func (c *Conn) handleWallops(
+	ctx context.Context,
+	msg *Message,
+) {
+	if len(msg.Params) < 1 {
+		c.sendNumeric(
+			irc.ErrNeedMoreParams,
+			irc.CmdWallops, "Not enough parameters",
+		)
+
+		return
+	}
+
+	err := c.svc.SendWallops(
+		ctx, c.sessionID, c.currentNick(), msg.Params[0],
+	)
+	if err != nil {
+		c.sendIRCError(err)
+	}
+}
diff --git a/internal/ircserver/conn.go b/internal/ircserver/conn.go
index fdd6b35..74e4dd1 100644
--- a/internal/ircserver/conn.go
+++ b/internal/ircserver/conn.go
@@ -22,6 +22,7 @@ const (
 	maxLineLen      = 512
 	readTimeout     = 5 * time.Minute
 	writeTimeout    = 30 * time.Second
+	killWriteWindow = 2 * time.Second
 	dnsTimeout      = 3 * time.Second
 	pollInterval    = 100 * time.Millisecond
 	pingInterval    = 90 * time.Second
@@ -46,6 +47,11 @@ type Conn struct {
 	serverSfx string
 	commands  map[string]cmdHandler
 
+	// writeMu serializes writes to conn, which come from
+	// serve(), from the relay goroutine and, for KILL, from
+	// Disconnect.
+	writeMu sync.Mutex
+
 	mu        sync.Mutex
 	nick      string
 	username  string
@@ -62,6 +68,7 @@ type Conn struct {
 
 	lastQueueID int64
 	closed      bool
+	killed      bool
 }
 
 func newConn(
@@ -97,6 +104,57 @@ func newConn(
 	return conn
 }
 
+// Disconnect ends the connection for an operator KILL from
+// either transport: the victim is sent KILL and ERROR, then
+// its socket is closed, which ends serve() and with it the
+// relay goroutine. It is called from the killer's goroutine
+// and does not wait for the writes, so a victim that has
+// stopped reading cannot stall the killer.
+func (c *Conn) Disconnect(reason string) {
+	c.mu.Lock()
+
+	if c.closed {
+		c.mu.Unlock()
+
+		return
+	}
+
+	c.closed = true
+	c.killed = true
+	nick := c.nick
+	host := c.hostname
+	c.mu.Unlock()
+
+	if nick == "" {
+		nick = "*"
+	}
+
+	go func() {
+		c.notifyKilledAndClose(nick, host, reason)
+	}()
+}
+
+// notifyKilledAndClose sends a killed victim the KILL and
+// ERROR lines, each bounded by killWriteWindow, and then
+// closes its socket.
+func (c *Conn) notifyKilledAndClose(
+	nick, host, reason string,
+) {
+	defer func() { _ = c.conn.Close() }()
+
+	c.sendWithin(
+		killWriteWindow,
+		FormatMessage(
+			c.serverSfx, irc.CmdKill, nick, reason,
+		),
+	)
+	c.sendWithin(
+		killWriteWindow,
+		"ERROR :Closing Link: "+host+
+			" ("+reason+")",
+	)
+}
+
 // buildCommandMap returns a map from IRC command strings
 // to handler functions.
 func (c *Conn) buildCommandMap() map[string]cmdHandler {
@@ -129,7 +187,13 @@ func (c *Conn) buildCommandMap() map[string]cmdHandler {
 		"CAP": func(_ context.Context, msg *Message) {
 			c.handleCAP(msg)
 		},
-		"USERHOST": c.handleUserhost,
+		irc.CmdUserhost: c.handleUserhost,
+		irc.CmdVersion:  func(context.Context, *Message) { c.handleVersion() },
+		irc.CmdAdmin:    func(context.Context, *Message) { c.handleAdmin() },
+		irc.CmdInfo:     func(context.Context, *Message) { c.handleInfo() },
+		irc.CmdTime:     func(context.Context, *Message) { c.handleTime() },
+		irc.CmdKill:     c.handleKill,
+		irc.CmdWallops:  c.handleWallops,
 	}
 }
 
@@ -180,7 +244,7 @@ func (c *Conn) serve(ctx context.Context) {
 
 		c.handleMessage(ctx, msg)
 
-		if c.closed {
+		if c.isClosed() {
 			return
 		}
 	}
@@ -189,24 +253,60 @@ func (c *Conn) serve(ctx context.Context) {
 func (c *Conn) cleanup(ctx context.Context) {
 	c.mu.Lock()
 	wasRegistered := c.registered
+	wasKilled := c.killed
 	sessID := c.sessionID
 	nick := c.nick
 	c.closed = true
 	c.mu.Unlock()
 
 	if wasRegistered && sessID > 0 {
-		c.svc.BroadcastQuit(
-			ctx, sessID, nick, "Connection closed",
-		)
+		c.svc.UnregisterWireConn(sessID, c)
+
+		// KILL has already sent the QUIT and deleted the
+		// session.
+		if !wasKilled {
+			c.svc.BroadcastQuit(
+				ctx, sessID, nick, "Connection closed",
+			)
+		}
 	}
 
 	c.conn.Close() //nolint:errcheck,gosec
 }
 
+// isClosed reports whether QUIT or KILL has ended the
+// connection.
+func (c *Conn) isClosed() bool {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	return c.closed
+}
+
+// currentNick returns c.nick, read under c.mu.
+func (c *Conn) currentNick() string {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	return c.nick
+}
+
 // send writes a formatted IRC line to the connection.
 func (c *Conn) send(line string) {
+	c.sendWithin(writeTimeout, line)
+}
+
+// sendWithin writes a formatted IRC line to the connection,
+// giving up after timeout.
+func (c *Conn) sendWithin(
+	timeout time.Duration,
+	line string,
+) {
+	c.writeMu.Lock()
+	defer c.writeMu.Unlock()
+
 	_ = c.conn.SetWriteDeadline(
-		time.Now().Add(writeTimeout),
+		time.Now().Add(timeout),
 	)
 
 	_, _ = fmt.Fprintf(c.conn, "%s\r\n", line)
@@ -387,7 +487,10 @@ func (c *Conn) completeRegistration(ctx context.Context) {
 			"failed to create session", "error", err,
 		)
 		c.send("ERROR :Internal server error")
+
+		c.mu.Lock()
 		c.closed = true
+		c.mu.Unlock()
 
 		return
 	}
@@ -398,6 +501,9 @@ func (c *Conn) completeRegistration(ctx context.Context) {
 	c.registered = true
 	c.mu.Unlock()
 
+	// So that KILL, from either transport, can close it.
+	c.svc.RegisterWireConn(sessionID, c)
+
 	// If PASS was provided before registration, set the
 	// session password.
 	if c.passWord != "" && len(c.passWord) >= minPasswordLen {
diff --git a/internal/ircserver/conn_test.go b/internal/ircserver/conn_test.go
new file mode 100644
index 0000000..75601a1
--- /dev/null
+++ b/internal/ircserver/conn_test.go
@@ -0,0 +1,100 @@
+package ircserver_test
+
+import (
+	"bufio"
+	"log/slog"
+	"net"
+	"os"
+	"strings"
+	"testing"
+	"time"
+
+	"sneak.berlin/go/neoirc/internal/config"
+	"sneak.berlin/go/neoirc/internal/ircserver"
+)
+
+// newKillVictim returns a Conn for the nick victim whose
+// socket is one end of a net.Pipe, and the other end, from
+// which the test reads what the victim is sent. A write to
+// the pipe blocks until the other end reads.
+func newKillVictim(t *testing.T) (*ircserver.Conn, net.Conn) {
+	t.Helper()
+
+	serverSide, clientSide := net.Pipe()
+
+	t.Cleanup(func() { _ = clientSide.Close() })
+
+	log := slog.New(slog.NewTextHandler(
+		os.Stderr,
+		&slog.HandlerOptions{Level: slog.LevelError},
+	))
+	cfg := &config.Config{ServerName: testServerName}
+
+	return ircserver.NewTestConn(
+		log, cfg, serverSide, "victim",
+	), clientSide
+}
+
+// TestDisconnectDoesNotBlockOnUnresponsiveVictim checks
+// that Disconnect returns although the victim never reads,
+// so a KILL cannot stall the operator who sent it.
+func TestDisconnectDoesNotBlockOnUnresponsiveVictim(
+	t *testing.T,
+) {
+	t.Parallel()
+
+	victim, _ := newKillVictim(t)
+	returned := make(chan struct{})
+
+	go func() {
+		victim.Disconnect("killed by oper")
+		close(returned)
+	}()
+
+	select {
+	case <-returned:
+	case <-time.After(testTimeout):
+		t.Fatal("Disconnect waited for the victim to read")
+	}
+}
+
+// TestDisconnectNotifiesAndClosesVictim checks that a
+// victim that reads is sent KILL and ERROR, and that its
+// connection is then closed.
+func TestDisconnectNotifiesAndClosesVictim(t *testing.T) {
+	t.Parallel()
+
+	victim, clientSide := newKillVictim(t)
+	received := make(chan []string, 1)
+
+	go func() {
+		var lines []string
+
+		scanner := bufio.NewScanner(clientSide)
+		for scanner.Scan() {
+			lines = append(lines, scanner.Text())
+		}
+
+		received <- lines
+	}()
+
+	victim.Disconnect("killed by oper")
+
+	var lines []string
+
+	select {
+	case lines = <-received:
+	case <-time.After(testTimeout):
+		t.Fatal("the victim's connection was not closed")
+	}
+
+	joined := strings.Join(lines, "\n")
+
+	if !strings.Contains(joined, "KILL victim :killed by oper") {
+		t.Errorf("missing KILL line, got: %q", joined)
+	}
+
+	if !strings.Contains(joined, "ERROR :Closing Link:") {
+		t.Errorf("missing ERROR line, got: %q", joined)
+	}
+}
diff --git a/internal/ircserver/export_test.go b/internal/ircserver/export_test.go
index 84e870b..2b8e08c 100644
--- a/internal/ircserver/export_test.go
+++ b/internal/ircserver/export_test.go
@@ -4,10 +4,12 @@ import (
 	"context"
 	"log/slog"
 	"net"
+	"time"
 
 	"sneak.berlin/go/neoirc/internal/broker"
 	"sneak.berlin/go/neoirc/internal/config"
 	"sneak.berlin/go/neoirc/internal/db"
+	"sneak.berlin/go/neoirc/internal/globals"
 	"sneak.berlin/go/neoirc/internal/service"
 )
 
@@ -19,8 +21,14 @@ func NewTestServer(
 	database *db.Database,
 	brk *broker.Broker,
 ) *Server {
+	globs := &globals.Globals{
+		Appname:   "neoirc",
+		Version:   "test",
+		StartTime: time.Now(),
+	}
+
 	svc := service.NewTestService(
-		database, brk, cfg, log,
+		database, brk, cfg, globs, log,
 	)
 
 	return &Server{ //nolint:exhaustruct
@@ -47,3 +55,20 @@ func (s *Server) Stop() {
 func (s *Server) Listener() net.Listener {
 	return s.listener
 }
+
+// NewTestConn returns a Conn for nick on tcpConn, without a
+// server, database or service behind it.
+func NewTestConn(
+	log *slog.Logger,
+	cfg *config.Config,
+	tcpConn net.Conn,
+	nick string,
+) *Conn {
+	conn := newConn(
+		context.Background(), tcpConn, log,
+		nil, nil, cfg, nil,
+	)
+	conn.nick = nick
+
+	return conn
+}
diff --git a/internal/ircserver/integration_test.go b/internal/ircserver/integration_test.go
index 57cd413..adb69f4 100644
--- a/internal/ircserver/integration_test.go
+++ b/internal/ircserver/integration_test.go
@@ -4,6 +4,8 @@ import (
 	"strings"
 	"testing"
 	"time"
+
+	"sneak.berlin/go/neoirc/internal/config"
 )
 
 // TestIntegrationTwoClients is a comprehensive integration
@@ -762,6 +764,371 @@ func TestIntegrationTwoClients(t *testing.T) {
 	)
 }
 
+// ── Tier 3 Utility Command Integration Tests ──────────
+
+// TestIntegrationUserhost verifies the USERHOST command
+// returns user@host info for connected nicks.
+func TestIntegrationUserhost(t *testing.T) {
+	t.Parallel()
+
+	env := newTestEnv(t)
+
+	alice := env.dial(t)
+	alice.register("alice")
+
+	bob := env.dial(t)
+	bob.register("bob")
+
+	bob.send("AWAY :lunch")
+	bob.readUntil(func(l string) bool {
+		return strings.Contains(l, " 306 ")
+	})
+
+	for _, step := range []struct {
+		line, want string
+	}{
+		{"USERHOST alice", " 302 alice alice=+alice@"},
+		{"USERHOST alice bob", " :alice=+alice@"},
+		{"USERHOST alice bob", " bob=-bob@"},
+		{"USERHOST nobody", " 302 alice :"},
+		{"USERHOST", " 461 alice USERHOST :"},
+	} {
+		alice.send(step.line)
+
+		reply := alice.readUntil(func(l string) bool {
+			return strings.Contains(l, " 302 ") ||
+				strings.Contains(l, " 461 ")
+		})
+		assertContains(t, reply, step.want, step.line)
+	}
+}
+
+// TestIntegrationVersion verifies the VERSION command
+// returns the server version string.
+func TestIntegrationVersion(t *testing.T) {
+	t.Parallel()
+
+	env := newTestEnv(t)
+
+	alice := env.dial(t)
+	alice.register("alice")
+
+	alice.send("VERSION")
+
+	aliceReply := alice.readUntil(func(l string) bool {
+		return strings.Contains(l, " 351 ")
+	})
+	assertContains(
+		t, aliceReply, " 351 ",
+		"RPL_VERSION",
+	)
+	assertContains(
+		t, aliceReply, "neoirc",
+		"VERSION reply contains server name",
+	)
+}
+
+// TestIntegrationAdmin verifies the ADMIN command returns
+// server admin info (256–259 numerics).
+func TestIntegrationAdmin(t *testing.T) {
+	t.Parallel()
+
+	env := newTestEnv(t)
+
+	alice := env.dial(t)
+	alice.register("alice")
+
+	alice.send("ADMIN")
+
+	aliceReply := alice.readUntil(func(l string) bool {
+		return strings.Contains(l, " 259 ")
+	})
+	assertContains(
+		t, aliceReply, " 256 ",
+		"RPL_ADMINME",
+	)
+	assertContains(
+		t, aliceReply, " 257 ",
+		"RPL_ADMINLOC1",
+	)
+	assertContains(
+		t, aliceReply, " 258 ",
+		"RPL_ADMINLOC2",
+	)
+	assertContains(
+		t, aliceReply, " 259 ",
+		"RPL_ADMINEMAIL",
+	)
+}
+
+// TestIntegrationInfo verifies the INFO command returns
+// server information (371/374 numerics).
+func TestIntegrationInfo(t *testing.T) {
+	t.Parallel()
+
+	env := newTestEnv(t)
+
+	alice := env.dial(t)
+	alice.register("alice")
+
+	alice.send("INFO")
+
+	aliceReply := alice.readUntil(func(l string) bool {
+		return strings.Contains(l, " 374 ")
+	})
+	assertContains(
+		t, aliceReply, " 371 ",
+		"RPL_INFO",
+	)
+	assertContains(
+		t, aliceReply, " 374 ",
+		"RPL_ENDOFINFO",
+	)
+	assertContains(
+		t, aliceReply, "neoirc",
+		"INFO reply mentions server name",
+	)
+}
+
+// TestIntegrationTime verifies the TIME command returns
+// the server time (391 numeric).
+func TestIntegrationTime(t *testing.T) {
+	t.Parallel()
+
+	env := newTestEnv(t)
+
+	alice := env.dial(t)
+	alice.register("alice")
+
+	alice.send("TIME")
+
+	aliceReply := alice.readUntil(func(l string) bool {
+		return strings.Contains(l, " 391 ")
+	})
+	assertContains(
+		t, aliceReply, " 391 ",
+		"RPL_TIME",
+	)
+	assertContains(
+		t, aliceReply, testServerName,
+		"TIME reply includes server name",
+	)
+}
+
+// becomeOper sends OPER with newTestEnvWithOper's
+// credentials and waits for RPL_YOUREOPER.
+func (tc *testClient) becomeOper() {
+	tc.t.Helper()
+
+	tc.send("OPER testoper testpass")
+	tc.readUntil(func(l string) bool {
+		return strings.Contains(l, " 381 ")
+	})
+}
+
+// TestIntegrationKillRefused covers the KILL errors: not an
+// operator, no such nick, and killing yourself.
+func TestIntegrationKillRefused(t *testing.T) {
+	t.Parallel()
+
+	env := newTestEnvWithOper(t)
+
+	alice := env.dial(t)
+	alice.register("alice")
+
+	bob := env.dial(t)
+	bob.register("bob")
+
+	for _, step := range []struct {
+		line, numeric string
+	}{
+		{"KILL bob :nope", " 481 "},
+		{"OPER testoper testpass", " 381 "},
+		{"KILL nobody123 :gone", " 401 "},
+		{"KILL alice :me", " 483 "},
+	} {
+		alice.send(step.line)
+
+		reply := alice.readUntil(func(l string) bool {
+			return strings.Contains(l, step.numeric)
+		})
+		assertContains(t, reply, step.numeric, step.line)
+	}
+}
+
+// TestIntegrationKill checks that the victim of a KILL is
+// told why, is disconnected, and is gone from its channels.
+func TestIntegrationKill(t *testing.T) {
+	t.Parallel()
+
+	env := newTestEnvWithOper(t)
+
+	alice := env.dial(t)
+	alice.register("alice")
+
+	bob := env.dial(t)
+	bob.register("bob")
+
+	alice.joinAndDrain("#killtest")
+	bob.joinAndDrain("#killtest")
+
+	// Drain alice's view of bob's join.
+	alice.readUntil(func(l string) bool {
+		return strings.Contains(l, "JOIN") &&
+			strings.Contains(l, "bob")
+	})
+
+	alice.becomeOper()
+	alice.send("KILL bob :bad behavior")
+
+	bobLines := bob.readUntilClosed()
+	assertContains(
+		t, bobLines, "KILL",
+		"victim receives KILL before disconnect",
+	)
+	assertContains(
+		t, bobLines, "ERROR :Closing Link",
+		"victim receives ERROR before disconnect",
+	)
+	assertContains(
+		t, bobLines, "bad behavior",
+		"KILL reason delivered to victim",
+	)
+
+	// alice should see bob's QUIT relay.
+	aliceSeesQuit := alice.readUntil(func(l string) bool {
+		return strings.Contains(l, "QUIT") &&
+			strings.Contains(l, "bob")
+	})
+	assertContains(
+		t, aliceSeesQuit, "Killed",
+		"KILL reason in QUIT message",
+	)
+
+	// bob must be gone from the channel member list.
+	alice.send("NAMES #killtest")
+
+	aliceNames := alice.readUntil(func(l string) bool {
+		return strings.Contains(l, " 366 ")
+	})
+	assertContains(
+		t, aliceNames, "alice",
+		"alice still in NAMES after killing bob",
+	)
+	assertNotContains(
+		t, aliceNames, "bob",
+		"killed user must not appear in NAMES",
+	)
+
+	// ...nor from WHO.
+	alice.send("WHO #killtest")
+
+	aliceWho := alice.readUntil(func(l string) bool {
+		return strings.Contains(l, " 315 ")
+	})
+	assertNotContains(
+		t, aliceWho, "bob",
+		"killed user must not appear in WHO",
+	)
+}
+
+// TestIntegrationWallops verifies the WALLOPS command:
+// oper can broadcast to +w users.
+func TestIntegrationWallops(t *testing.T) {
+	t.Parallel()
+
+	env := newTestEnvWithOper(t)
+
+	alice := env.dial(t)
+	alice.register("alice")
+
+	bob := env.dial(t)
+	bob.register("bob")
+
+	// Non-oper WALLOPS should fail.
+	alice.send("WALLOPS :test broadcast")
+
+	aliceWallopsFail := alice.readUntil(func(l string) bool {
+		return strings.Contains(l, " 481 ")
+	})
+	assertContains(
+		t, aliceWallopsFail, " 481 ",
+		"ERR_NOPRIVILEGES for non-oper WALLOPS",
+	)
+
+	alice.becomeOper()
+
+	// bob sets +w to receive wallops.
+	bob.send("MODE bob +w")
+	bob.readUntil(func(l string) bool {
+		return strings.Contains(l, " 221 ")
+	})
+
+	// alice sends WALLOPS.
+	alice.send("WALLOPS :important announcement")
+
+	// bob (who has +w) should receive it.
+	bobWallops := bob.readUntil(func(l string) bool {
+		return strings.Contains(
+			l, "important announcement",
+		)
+	})
+	assertContains(
+		t, bobWallops, "important announcement",
+		"bob receives WALLOPS message",
+	)
+	assertContains(
+		t, bobWallops, "WALLOPS",
+		"message is WALLOPS command",
+	)
+}
+
+// TestIntegrationUserMode covers MODE for a nick: changes
+// and queries of your own modes in any letter case, refusal
+// for another nick, and a rejected mode string changing
+// nothing.
+func TestIntegrationUserMode(t *testing.T) {
+	t.Parallel()
+
+	env := newTestEnv(t)
+
+	alice := env.dial(t)
+	alice.register("alice")
+
+	bob := env.dial(t)
+	bob.register("bob")
+
+	const (
+		notYours = " 502 alice :Can't change mode for other users"
+		unknown  = " 501 alice :Unknown MODE flag"
+	)
+
+	for _, step := range []struct {
+		line, want string
+	}{
+		{"MODE ALICE +w", " 221 alice +w"},
+		{"MODE bob", notYours},
+		{"MODE bob -w", notYours},
+		{"MODE alice xw", unknown},
+		{"MODE alice -w+z", unknown},
+		{"MODE alice", " 221 alice +w"},
+		{"MODE alice +w-w", " 221 alice +"},
+	} {
+		alice.send(step.line)
+
+		reply := alice.readUntil(func(l string) bool {
+			return strings.Contains(l, " 221 ") ||
+				strings.Contains(l, " 501 ") ||
+				strings.Contains(l, " 502 ")
+		})
+
+		last := reply[len(reply)-1]
+		if !strings.HasSuffix(last, step.want) {
+			t.Errorf("%s: want %q, got %q", step.line, step.want, last)
+		}
+	}
+}
+
 // TestIntegrationModeSecret tests +s (secret) channel
 // mode — verifies that +s can be set and the mode is
 // reflected in MODE queries.
@@ -915,3 +1282,30 @@ func TestIntegrationThirdClientObserver(t *testing.T) {
 		"carol receives trio message",
 	)
 }
+
+// TestIntegrationDefaultServerNameFallback checks that with
+// SERVER_NAME unset, as it is by default, VERSION, ADMIN and
+// TIME name the server "neoirc".
+func TestIntegrationDefaultServerNameFallback(t *testing.T) {
+	t.Parallel()
+
+	env := newTestEnvWithConfig(t, &config.Config{})
+
+	alice := env.dial(t)
+	alice.register("alice")
+
+	for _, step := range []struct {
+		line, lastNumeric, want string
+	}{
+		{"VERSION", " 351 ", " 351 alice neoirc-test. neoirc "},
+		{"ADMIN", " 259 ", " 256 alice neoirc "},
+		{"TIME", " 391 ", " 391 alice neoirc "},
+	} {
+		alice.send(step.line)
+
+		reply := alice.readUntil(func(l string) bool {
+			return strings.Contains(l, step.lastNumeric)
+		})
+		assertContains(t, reply, step.want, step.line)
+	}
+}
diff --git a/internal/ircserver/relay.go b/internal/ircserver/relay.go
index 6d4195f..60ccb74 100644
--- a/internal/ircserver/relay.go
+++ b/internal/ircserver/relay.go
@@ -120,6 +120,8 @@ func (c *Conn) deliverIRCMessage(
 		c.deliverKickMsg(msg, text)
 	case command == "INVITE":
 		c.deliverInviteMsg(msg, text)
+	case command == irc.CmdWallops:
+		c.deliverWallops(msg, text)
 	case command == irc.CmdMode:
 		c.deliverMode(msg, text)
 	case command == irc.CmdPing:
@@ -337,6 +339,18 @@ func (c *Conn) deliverInviteMsg(
 	c.sendFromServer("NOTICE", nick, text)
 }
 
+// deliverWallops sends a WALLOPS notification.
+func (c *Conn) deliverWallops(
+	msg *db.IRCMessage,
+	text string,
+) {
+	prefix := msg.From + "!" + msg.From + "@*"
+
+	c.send(FormatMessage(
+		prefix, irc.CmdWallops, text,
+	))
+}
+
 // deliverMode sends a MODE change notification.
 func (c *Conn) deliverMode(
 	msg *db.IRCMessage,
diff --git a/internal/ircserver/server_test.go b/internal/ircserver/server_test.go
index 0ea6f4e..3717474 100644
--- a/internal/ircserver/server_test.go
+++ b/internal/ircserver/server_test.go
@@ -36,9 +36,39 @@ type testEnv struct {
 	srv      *ircserver.Server
 }
 
+// testServerName is the SERVER_NAME of newTestEnv.
+const testServerName = "test.irc"
+
 func newTestEnv(t *testing.T) *testEnv {
 	t.Helper()
 
+	return newTestEnvWithConfig(t, &config.Config{
+		ServerName: testServerName,
+		MOTD:       "Welcome to test IRC",
+	})
+}
+
+// newTestEnvWithOper is newTestEnv with the operator name
+// testoper and password testpass.
+func newTestEnvWithOper(t *testing.T) *testEnv {
+	t.Helper()
+
+	return newTestEnvWithConfig(t, &config.Config{
+		ServerName:   testServerName,
+		MOTD:         "Welcome to test IRC",
+		OperName:     "testoper",
+		OperPassword: "testpass",
+	})
+}
+
+// newTestEnvWithConfig starts an IRC server with cfg on a
+// fresh database.
+func newTestEnvWithConfig(
+	t *testing.T,
+	cfg *config.Config,
+) *testEnv {
+	t.Helper()
+
 	dsn := fmt.Sprintf(
 		"file:%s?mode=memory&cache=shared&_journal_mode=WAL",
 		t.Name(),
@@ -67,11 +97,6 @@ func newTestEnv(t *testing.T) *testEnv {
 
 	brk := broker.New()
 
-	cfg := &config.Config{ //nolint:exhaustruct
-		ServerName: "test.irc",
-		MOTD:       "Welcome to test IRC",
-	}
-
 	var listenConfig net.ListenConfig
 
 	listener, err := listenConfig.Listen(t.Context(), "tcp", "127.0.0.1:0")
@@ -215,6 +240,33 @@ func (tc *testClient) register(nick string) []string {
 	})
 }
 
+// readUntilClosed returns the lines received until the
+// server closes the connection, and fails the test if it is
+// still open after testTimeout.
+func (tc *testClient) readUntilClosed() []string {
+	tc.t.Helper()
+
+	_ = tc.conn.SetReadDeadline(
+		time.Now().Add(testTimeout),
+	)
+
+	var lines []string
+
+	for tc.scanner.Scan() {
+		lines = append(lines, tc.scanner.Text())
+	}
+
+	err := tc.scanner.Err()
+	if err != nil {
+		tc.t.Fatalf(
+			"connection not closed: %v (lines: %v)",
+			err, lines,
+		)
+	}
+
+	return lines
+}
+
 // assertContains checks that at least one line matches the
 // given substring.
 func assertContains(
@@ -233,6 +285,27 @@ func assertContains(
 	t.Errorf("did not find %q in output: %s", substr, description)
 }
 
+// assertNotContains checks that no line matches the given
+// substring.
+func assertNotContains(
+	t *testing.T,
+	lines []string,
+	substr, description string,
+) {
+	t.Helper()
+
+	for _, line := range lines {
+		if strings.Contains(line, substr) {
+			t.Errorf(
+				"unexpectedly found %q in output: %s",
+				substr, description,
+			)
+
+			return
+		}
+	}
+}
+
 // joinAndDrain joins a channel and reads until
 // RPL_ENDOFNAMES.
 func (tc *testClient) joinAndDrain(channel string) {
diff --git a/internal/service/service.go b/internal/service/service.go
index 690ce08..16e2fa4 100644
--- a/internal/service/service.go
+++ b/internal/service/service.go
@@ -5,16 +5,21 @@ package service
 import (
 	"context"
 	"crypto/subtle"
+	"database/sql"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"log/slog"
 	"strconv"
 	"strings"
+	"sync"
+	"time"
 
 	"go.uber.org/fx"
 	"sneak.berlin/go/neoirc/internal/broker"
 	"sneak.berlin/go/neoirc/internal/config"
 	"sneak.berlin/go/neoirc/internal/db"
+	"sneak.berlin/go/neoirc/internal/globals"
 	"sneak.berlin/go/neoirc/internal/logger"
 	"sneak.berlin/go/neoirc/pkg/irc"
 )
@@ -22,9 +27,14 @@ import (
 // Error texts that several commands reply with.
 const (
 	msgNoSuchChannel = "No such channel"
+	msgNoSuchNick    = "No such nick/channel"
 	msgNotChannelOp  = "You're not channel operator"
 )
 
+// maxUserhostNicks is how many nicks one USERHOST answers
+// for (RFC 2812).
+const maxUserhostNicks = 5
+
 // Params defines the dependencies for creating a Service.
 type Params struct {
 	fx.In
@@ -33,23 +43,38 @@ type Params struct {
 	Config   *config.Config
 	Database *db.Database
 	Broker   *broker.Broker
+	Globals  *globals.Globals
+}
+
+// WireConn is a registered IRC connection, which KILL closes.
+// HTTP clients hold no connection and register none.
+type WireConn interface {
+	// Disconnect tells the client why and closes the
+	// connection.
+	Disconnect(reason string)
 }
 
 // Service provides shared business logic for IRC commands.
 type Service struct {
-	db     *db.Database
-	broker *broker.Broker
-	config *config.Config
-	log    *slog.Logger
+	db      *db.Database
+	broker  *broker.Broker
+	config  *config.Config
+	globals *globals.Globals
+	log     *slog.Logger
+
+	wireMu    sync.Mutex
+	wireConns map[int64]WireConn
 }
 
 // New creates a new Service.
 func New(params Params) *Service {
 	return &Service{
-		db:     params.Database,
-		broker: params.Broker,
-		config: params.Config,
-		log:    params.Logger.Get(),
+		db:        params.Database,
+		broker:    params.Broker,
+		config:    params.Config,
+		globals:   params.Globals,
+		log:       params.Logger.Get(),
+		wireConns: make(map[int64]WireConn),
 	}
 }
 
@@ -59,16 +84,205 @@ func NewTestService(
 	database *db.Database,
 	brk *broker.Broker,
 	cfg *config.Config,
+	globs *globals.Globals,
 	log *slog.Logger,
 ) *Service {
 	return &Service{
-		db:     database,
-		broker: brk,
-		config: cfg,
-		log:    log,
+		db:        database,
+		broker:    brk,
+		config:    cfg,
+		globals:   globs,
+		log:       log,
+		wireConns: make(map[int64]WireConn),
 	}
 }
 
+// ServerVersion returns the version that VERSION and INFO
+// report on both transports, such as "neoirc-1.2.3".
+func (s *Service) ServerVersion() string {
+	version := s.globals.Version
+	if version == "" {
+		version = "dev"
+	}
+
+	return s.globals.Appname + "-" + version
+}
+
+// InfoLines returns the lines that INFO sends on both
+// transports.
+func (s *Service) InfoLines() []string {
+	return []string{
+		"neoirc — IRC semantics over HTTP",
+		"Version: " + s.ServerVersion(),
+		"Written in Go",
+		"Started: " + s.globals.StartTime.Format(time.RFC1123),
+	}
+}
+
+// UserhostReply returns the RPL_USERHOST text for the first
+// five of the given nicks: "nick=+user@host" entries joined
+// by spaces, with * after the nick of an operator and - in
+// place of + for a user who is away. Nicks with no session
+// are left out. An empty hostname is reported as
+// serverName.
+func (s *Service) UserhostReply(
+	ctx context.Context,
+	nicks []string,
+	serverName string,
+) (string, error) {
+	if len(nicks) > maxUserhostNicks {
+		nicks = nicks[:maxUserhostNicks]
+	}
+
+	infos, err := s.db.GetUserhostInfo(ctx, nicks)
+	if err != nil {
+		return "", fmt.Errorf("userhost: %w", err)
+	}
+
+	replies := make([]string, 0, len(infos))
+
+	for _, info := range infos {
+		operStar := ""
+		if info.IsOper {
+			operStar = "*"
+		}
+
+		away := "+"
+		if info.AwayMessage != "" {
+			away = "-"
+		}
+
+		username := info.Username
+		if username == "" {
+			username = info.Nick
+		}
+
+		hostname := info.Hostname
+		if hostname == "" {
+			hostname = serverName
+		}
+
+		replies = append(replies,
+			info.Nick+operStar+"="+away+username+"@"+hostname,
+		)
+	}
+
+	return strings.Join(replies, " "), nil
+}
+
+// RegisterWireConn records the IRC connection of a session,
+// so that KillUser can close it.
+func (s *Service) RegisterWireConn(
+	sessionID int64,
+	conn WireConn,
+) {
+	s.wireMu.Lock()
+	defer s.wireMu.Unlock()
+
+	s.wireConns[sessionID] = conn
+}
+
+// UnregisterWireConn removes what RegisterWireConn recorded,
+// unless the session has since registered another
+// connection.
+func (s *Service) UnregisterWireConn(
+	sessionID int64,
+	conn WireConn,
+) {
+	s.wireMu.Lock()
+	defer s.wireMu.Unlock()
+
+	if s.wireConns[sessionID] == conn {
+		delete(s.wireConns, sessionID)
+	}
+}
+
+// KillUser carries out an operator's KILL: the target's
+// channel peers see it quit, its session is deleted, and
+// its IRC connection, if it has one, is closed.
+func (s *Service) KillUser(
+	ctx context.Context,
+	sessionID int64,
+	nick, targetNick, reason string,
+) error {
+	err := s.requireOper(ctx, sessionID)
+	if err != nil {
+		return err
+	}
+
+	targetSID, err := s.db.GetSessionByNick(ctx, targetNick)
+	if errors.Is(err, sql.ErrNoRows) {
+		return &IRCError{
+			irc.ErrNoSuchNick,
+			[]string{targetNick},
+			msgNoSuchNick,
+		}
+	}
+
+	if err != nil {
+		return fmt.Errorf("kill: %w", err)
+	}
+
+	if targetSID == sessionID {
+		return &IRCError{
+			irc.ErrCantKillServer,
+			nil,
+			"You cannot KILL yourself",
+		}
+	}
+
+	quitReason := "Killed (" + nick + " (" + reason + "))"
+
+	s.BroadcastQuit(ctx, targetSID, targetNick, quitReason)
+
+	s.wireMu.Lock()
+	conn := s.wireConns[targetSID]
+	s.wireMu.Unlock()
+
+	if conn != nil {
+		conn.Disconnect(quitReason)
+	}
+
+	return nil
+}
+
+// SendWallops carries out an operator's WALLOPS: the
+// message goes to every user with user mode +w.
+func (s *Service) SendWallops(
+	ctx context.Context,
+	sessionID int64,
+	nick, message string,
+) error {
+	err := s.requireOper(ctx, sessionID)
+	if err != nil {
+		return err
+	}
+
+	recipients, err := s.db.GetWallopsSessionIDs(ctx)
+	if err != nil {
+		return fmt.Errorf("wallops: %w", err)
+	}
+
+	if len(recipients) == 0 {
+		return nil
+	}
+
+	body, err := json.Marshal([]string{message})
+	if err != nil {
+		return fmt.Errorf("wallops: %w", err)
+	}
+
+	_, _, err = s.FanOut(
+		ctx, irc.CmdWallops, nick, "*",
+		nil, body, nil, recipients,
+	)
+	if err != nil {
+		return fmt.Errorf("wallops: %w", err)
+	}
+
+	return nil
+}
+
 // IRCError represents an IRC protocol-level error with a
 // numeric code that both transports can map to responses.
 type IRCError struct {
@@ -437,7 +651,7 @@ func (s *Service) KickUser(
 		return &IRCError{
 			irc.ErrNoSuchNick,
 			[]string{targetNick},
-			"No such nick/channel",
+			msgNoSuchNick,
 		}
 	}
 
@@ -649,7 +863,7 @@ func (s *Service) ApplyMemberMode(
 		return &IRCError{
 			irc.ErrNoSuchNick,
 			[]string{targetNick},
-			"No such nick/channel",
+			msgNoSuchNick,
 		}
 	}
 
@@ -792,6 +1006,139 @@ func (s *Service) QueryChannelMode(
 	return modes + modeParams
 }
 
+// QueryUserMode returns the session's user mode string,
+// such as "+", "+w" or "+ow".
+func (s *Service) QueryUserMode(
+	ctx context.Context,
+	sessionID int64,
+) (string, error) {
+	modes := "+"
+
+	isOper, err := s.db.IsSessionOper(ctx, sessionID)
+	if err != nil {
+		return "", fmt.Errorf(
+			"query oper flag: %w", err,
+		)
+	}
+
+	if isOper {
+		modes += "o"
+	}
+
+	isWallops, err := s.db.IsSessionWallops(
+		ctx, sessionID,
+	)
+	if err != nil {
+		return "", fmt.Errorf(
+			"query wallops flag: %w", err,
+		)
+	}
+
+	if isWallops {
+		modes += "w"
+	}
+
+	return modes, nil
+}
+
+// ApplyUserMode applies a user mode string to the session
+// and returns the resulting mode string. The whole string
+// is parsed before anything is written, and the flags are
+// written in one transaction, so a change that is rejected
+// or fails leaves the modes as they were.
+func (s *Service) ApplyUserMode(
+	ctx context.Context,
+	sessionID int64,
+	modeStr string,
+) (string, error) {
+	wallops, oper, err := parseUserModeString(modeStr)
+	if err != nil {
+		return "", err
+	}
+
+	err = s.db.SetSessionUserModes(
+		ctx, sessionID, wallops, oper,
+	)
+	if err != nil {
+		return "", fmt.Errorf("apply user modes: %w", err)
+	}
+
+	return s.QueryUserMode(ctx, sessionID)
+}
+
+// parseUserModeString parses a user mode string such as
+// "+w", "-o" or "+w-o" into the new value of each flag it
+// names, or nil for a flag it does not name; a later letter
+// overrides an earlier one. The string must start with + or
+// - and name at least one mode. w may be set or unset, o
+// only unset (OPER sets it). Anything else is rejected with
+// ERR_UMODEUNKNOWNFLAG.
+func parseUserModeString(
+	modeStr string,
+) (*bool, *bool, error) {
+	unknownFlag := &IRCError{
+		irc.ErrUmodeUnknownFlag, nil, "Unknown MODE flag",
+	}
+
+	if !strings.HasPrefix(modeStr, "+") &&
+		!strings.HasPrefix(modeStr, "-") {
+		return nil, nil, unknownFlag
+	}
+
+	var wallops, oper *bool
+
+	adding := true
+
+	for _, modeChar := range modeStr {
+		switch modeChar {
+		case '+':
+			adding = true
+		case '-':
+			adding = false
+		case 'w':
+			value := adding
+			wallops = &value
+		case 'o':
+			if adding {
+				return nil, nil, unknownFlag
+			}
+
+			value := false
+			oper = &value
+		default:
+			return nil, nil, unknownFlag
+		}
+	}
+
+	if wallops == nil && oper == nil {
+		return nil, nil, unknownFlag
+	}
+
+	return wallops, oper, nil
+}
+
+// requireOper returns ERR_NOPRIVILEGES unless the session
+// is a server operator.
+func (s *Service) requireOper(
+	ctx context.Context,
+	sessionID int64,
+) error {
+	isOper, err := s.db.IsSessionOper(ctx, sessionID)
+	if err != nil {
+		return fmt.Errorf("check oper: %w", err)
+	}
+
+	if !isOper {
+		return &IRCError{
+			irc.ErrNoPrivileges,
+			nil,
+			"Permission Denied- You're not an IRC operator",
+		}
+	}
+
+	return nil
+}
+
 // broadcastNickChange notifies channel peers of a nick
 // change.
 func (s *Service) broadcastNickChange(
diff --git a/internal/service/service_test.go b/internal/service/service_test.go
index 864a8a8..933235d 100644
--- a/internal/service/service_test.go
+++ b/internal/service/service_test.go
@@ -10,7 +10,10 @@ import (
 	"errors"
 	"fmt"
 	"os"
+	"slices"
+	"strings"
 	"testing"
+	"time"
 
 	"go.uber.org/fx"
 	"go.uber.org/fx/fxtest"
@@ -55,9 +58,10 @@ func newTestEnv(t *testing.T) *testEnv {
 	app := fxtest.New(t,
 		fx.Provide(
 			func() *globals.Globals {
-				return &globals.Globals{ //nolint:exhaustruct
-					Appname: "neoirc-test",
-					Version: "test",
+				return &globals.Globals{
+					Appname:   "neoirc-test",
+					Version:   "test",
+					StartTime: time.Now(),
 				}
 			},
 			logger.New,
@@ -363,3 +367,229 @@ func TestSendChannelMessage_Moderated(t *testing.T) {
 		t.Errorf("operator should be able to send in moderated channel: %v", err)
 	}
 }
+
+func TestQueryUserMode(t *testing.T) {
+	env := newTestEnv(t)
+	ctx := t.Context()
+
+	sid := createSession(ctx, t, env.db, "alice")
+
+	modes, err := env.svc.QueryUserMode(ctx, sid)
+	if err != nil {
+		t.Fatalf("query user mode: %v", err)
+	}
+
+	if modes != "+" {
+		t.Errorf("expected +, got %s", modes)
+	}
+
+	setUserModes(ctx, t, env.db, sid, userModes{wallops: true})
+
+	modes, err = env.svc.QueryUserMode(ctx, sid)
+	if err != nil {
+		t.Fatalf("query user mode: %v", err)
+	}
+
+	if modes != "+w" {
+		t.Errorf("expected +w, got %s", modes)
+	}
+
+	setUserModes(
+		ctx, t, env.db, sid, userModes{oper: true, wallops: true},
+	)
+
+	modes, err = env.svc.QueryUserMode(ctx, sid)
+	if err != nil {
+		t.Fatalf("query user mode: %v", err)
+	}
+
+	if modes != "+ow" {
+		t.Errorf("expected +ow, got %s", modes)
+	}
+}
+
+func TestUserhostReply(t *testing.T) {
+	env := newTestEnv(t)
+	ctx := t.Context()
+
+	createSession(ctx, t, env.db, "alice")
+	bobID := createSession(ctx, t, env.db, "bob")
+
+	// No username or hostname, and an operator.
+	operID, _, _, err := env.db.CreateSession(
+		ctx, "oper", "", "", "",
+	)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	setUserModes(ctx, t, env.db, operID, userModes{oper: true})
+
+	_, err = env.svc.SetAway(ctx, bobID, "gone fishing")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	reply, err := env.svc.UserhostReply(ctx, []string{
+		"alice", "bob", "nobody", "oper",
+	}, "srv")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	want := "alice=+alice@localhost bob=-bob@localhost " +
+		"oper*=+oper@srv"
+	if reply != want {
+		t.Errorf("want %q, got %q", want, reply)
+	}
+
+	reply, err = env.svc.UserhostReply(
+		ctx, slices.Repeat([]string{"bob"}, 6), "srv",
+	)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if strings.Count(reply, "bob=") != 5 {
+		t.Errorf("want 5 entries for 6 nicks, got %q", reply)
+	}
+}
+
+// userModes is the stored state of a session's user mode
+// flags.
+type userModes struct {
+	oper    bool
+	wallops bool
+}
+
+// applyUserModeTest is one mode string, the flags stored
+// before it is applied, and the expected outcome. An empty
+// wantModes means the string is rejected with
+// ERR_UMODEUNKNOWNFLAG, and then after must equal before.
+type applyUserModeTest struct {
+	modeStr   string
+	before    userModes
+	wantModes string
+	after     userModes
+}
+
+func applyUserModeTests() []applyUserModeTest {
+	none := userModes{}
+	oper := userModes{oper: true}
+	wallops := userModes{wallops: true}
+	both := userModes{oper: true, wallops: true}
+
+	return []applyUserModeTest{
+		{"+w", none, "+w", wallops},
+		{"-w", wallops, "+", none},
+		{"-o", oper, "+", none},
+		{"-wo", both, "+", none},
+		{"+w-o", oper, "+w", wallops},
+		{"-w+w", none, "+w", wallops},
+		{"+w-w", wallops, "+", none},
+		{"-w+o", both, "", both},
+		{"+o-w+w", both, "", both},
+		{"+wo", none, "", none},
+		{"+wz", none, "", none},
+		{"+z", none, "", none},
+		{"-x+y", none, "", none},
+		{"+y-x", none, "", none},
+		{"w", none, "", none},
+		{"xw", wallops, "", wallops},
+		{"", none, "", none},
+		{"+", none, "", none},
+		{"-", none, "", none},
+		{"+-+", none, "", none},
+	}
+}
+
+func TestApplyUserMode(t *testing.T) {
+	env := newTestEnv(t)
+
+	for i, test := range applyUserModeTests() {
+		t.Run(test.modeStr, func(t *testing.T) {
+			ctx := t.Context()
+			sid := createSession(
+				ctx, t, env.db, fmt.Sprintf("user%d", i),
+			)
+			setUserModes(ctx, t, env.db, sid, test.before)
+
+			modes, err := env.svc.ApplyUserMode(
+				ctx, sid, test.modeStr,
+			)
+			checkApplyUserModeResult(t, test.wantModes, modes, err)
+
+			got := getUserModes(ctx, t, env.db, sid)
+			if got != test.after {
+				t.Errorf(
+					"stored modes: want %+v, got %+v",
+					test.after, got,
+				)
+			}
+		})
+	}
+}
+
+func checkApplyUserModeResult(
+	t *testing.T,
+	wantModes, modes string,
+	err error,
+) {
+	t.Helper()
+
+	if wantModes == "" {
+		var ircErr *service.IRCError
+		if !errors.As(err, &ircErr) ||
+			ircErr.Code != irc.ErrUmodeUnknownFlag {
+			t.Fatalf("want ERR_UMODEUNKNOWNFLAG, got %v", err)
+		}
+
+		return
+	}
+
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	if modes != wantModes {
+		t.Errorf("modes: want %q, got %q", wantModes, modes)
+	}
+}
+
+func setUserModes(
+	ctx context.Context,
+	t *testing.T,
+	database *db.Database,
+	sid int64,
+	modes userModes,
+) {
+	t.Helper()
+
+	err := database.SetSessionUserModes(
+		ctx, sid, &modes.wallops, &modes.oper,
+	)
+	if err != nil {
+		t.Fatalf("set user modes: %v", err)
+	}
+}
+
+func getUserModes(
+	ctx context.Context,
+	t *testing.T,
+	database *db.Database,
+	sid int64,
+) userModes {
+	t.Helper()
+
+	oper, err := database.IsSessionOper(ctx, sid)
+	if err != nil {
+		t.Fatalf("read oper: %v", err)
+	}
+
+	wallops, err := database.IsSessionWallops(ctx, sid)
+	if err != nil {
+		t.Fatalf("read wallops: %v", err)
+	}
+
+	return userModes{oper: oper, wallops: wallops}
+}
diff --git a/pkg/irc/commands.go b/pkg/irc/commands.go
index 60ef85e..4e2e8af 100644
--- a/pkg/irc/commands.go
+++ b/pkg/irc/commands.go
@@ -2,26 +2,33 @@ package irc
 
 // IRC command names (RFC 1459 / RFC 2812).
 const (
-	CmdAway    = "AWAY"
-	CmdInvite  = "INVITE"
-	CmdJoin    = "JOIN"
-	CmdKick    = "KICK"
-	CmdList    = "LIST"
-	CmdLusers  = "LUSERS"
-	CmdMode    = "MODE"
-	CmdMotd    = "MOTD"
-	CmdNames   = "NAMES"
-	CmdNick    = "NICK"
-	CmdNotice  = "NOTICE"
-	CmdOper    = "OPER"
-	CmdPass    = "PASS"
-	CmdPart    = "PART"
-	CmdPing    = "PING"
-	CmdPong    = "PONG"
-	CmdPrivmsg = "PRIVMSG"
-	CmdQuit    = "QUIT"
-	CmdTopic   = "TOPIC"
-	CmdUser    = "USER"
-	CmdWho     = "WHO"
-	CmdWhois   = "WHOIS"
+	CmdAdmin    = "ADMIN"
+	CmdAway     = "AWAY"
+	CmdInfo     = "INFO"
+	CmdInvite   = "INVITE"
+	CmdJoin     = "JOIN"
+	CmdKick     = "KICK"
+	CmdKill     = "KILL"
+	CmdList     = "LIST"
+	CmdLusers   = "LUSERS"
+	CmdMode     = "MODE"
+	CmdMotd     = "MOTD"
+	CmdNames    = "NAMES"
+	CmdNick     = "NICK"
+	CmdNotice   = "NOTICE"
+	CmdOper     = "OPER"
+	CmdPass     = "PASS"
+	CmdPart     = "PART"
+	CmdPing     = "PING"
+	CmdPong     = "PONG"
+	CmdPrivmsg  = "PRIVMSG"
+	CmdQuit     = "QUIT"
+	CmdTime     = "TIME"
+	CmdTopic    = "TOPIC"
+	CmdUser     = "USER"
+	CmdUserhost = "USERHOST"
+	CmdVersion  = "VERSION"
+	CmdWallops  = "WALLOPS"
+	CmdWho      = "WHO"
+	CmdWhois    = "WHOIS"
 )