diff --git a/conf/nginx-ssl.conf b/conf/nginx-ssl.conf
index 621973df..3623c5f6 100644
--- a/conf/nginx-ssl.conf
+++ b/conf/nginx-ssl.conf
@@ -2,7 +2,7 @@
 # Note that these settings are repeated in the SMTP and IMAP configuration.
 # ssl_protocols has moved to nginx.conf in bionic, check there for enabled protocols.
 ssl_ciphers ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:DHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES256-GCM-SHA384;
-ssl_dhparam STORAGE_ROOT/ssl/dh2048.pem;
+ssl_dhparam STORAGE_ROOT/ssl/dh4096.pem;
 
 # as recommended by http://nginx.org/en/docs/http/configuring_https_servers.html
 ssl_session_cache shared:SSL:50m;
diff --git a/management/web_update.py b/management/web_update.py
index c846f6e0..73ec4157 100644
--- a/management/web_update.py
+++ b/management/web_update.py
@@ -211,9 +211,9 @@ def make_domain_config(domain, templates, ssl_certificates, env):
 
 	# Add the HSTS header.
 	if hsts == "yes":
-		nginx_conf_extra += "\tadd_header Strict-Transport-Security \"max-age=15768000\" always;\n"
+		nginx_conf_extra += "\tadd_header Strict-Transport-Security \"max-age=31536000\" always;\n"
 	elif hsts == "preload":
-		nginx_conf_extra += "\tadd_header Strict-Transport-Security \"max-age=15768000; includeSubDomains; preload\" always;\n"
+		nginx_conf_extra += "\tadd_header Strict-Transport-Security \"max-age=31536000; includeSubDomains; preload\" always;\n"
 
 	# Add in any user customizations in the includes/ folder.
 	nginx_conf_custom_include = os.path.join(env["STORAGE_ROOT"], "www", safe_domain_name(domain) + ".conf")
diff --git a/setup/mail-dovecot.sh b/setup/mail-dovecot.sh
index 63810c50..5482d04f 100755
--- a/setup/mail-dovecot.sh
+++ b/setup/mail-dovecot.sh
@@ -77,23 +77,16 @@ tools/editconf.py /etc/dovecot/conf.d/10-auth.conf \
 	disable_plaintext_auth=yes \
 	"auth_mechanisms=plain login"
 
-# Generate DH parameters. Will take a long time, so only if they don't exist
-if [[ ! -f  /etc/dovecot/dh.pem ]]; then
-	openssl dhparam -out /etc/dovecot/dh.pem 4096
-fi
-
-chown mail:dovecot /etc/dovecot/dh.pem
-
 # Enable SSL, specify the location of the SSL certificate and private key files.
 # Use Mozilla's "Intermediate" recommendations at https://ssl-config.mozilla.org/#server=dovecot&server-version=2.2.33&config=intermediate&openssl-version=1.1.1,
-# except that the current version of Dovecot does not have a TLSv1.3 setting, so we only use TLSv1.2.
+# specify a minimum of TLSv1.2.
 tools/editconf.py /etc/dovecot/conf.d/10-ssl.conf \
 	ssl=required \
 	"ssl_cert=<$STORAGE_ROOT/ssl/ssl_certificate.pem" \
 	"ssl_key=<$STORAGE_ROOT/ssl/ssl_private_key.pem" \
 	"ssl_min_protocol=TLSv1.2" \
 	"ssl_prefer_server_ciphers=yes" \
-	"ssl_dh=</etc/dovecot/dh.pem"
+	"ssl_dh=<$STORAGE_ROOT/ssl/dh4096.pem"
 
 # Disable in-the-clear IMAP/POP because there is no reason for a user to transmit
 # login credentials outside of an encrypted connection. Only the over-TLS versions
diff --git a/setup/mail-postfix.sh b/setup/mail-postfix.sh
index 208613cb..618fce19 100755
--- a/setup/mail-postfix.sh
+++ b/setup/mail-postfix.sh
@@ -128,7 +128,7 @@ tools/editconf.py /etc/postfix/main.cf \
 	smtpd_tls_auth_only=yes \
 	smtpd_tls_cert_file=$STORAGE_ROOT/ssl/ssl_certificate.pem \
 	smtpd_tls_key_file=$STORAGE_ROOT/ssl/ssl_private_key.pem \
-	smtpd_tls_dh1024_param_file=$STORAGE_ROOT/ssl/dh2048.pem \
+	smtpd_tls_dh1024_param_file=$STORAGE_ROOT/ssl/dh4096.pem \
 	smtpd_tls_protocols="!SSLv2,!SSLv3,!TLSv1,!TLSv1.1" \
 	smtpd_tls_ciphers=medium \
 	tls_medium_cipherlist=ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:DHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES256-GCM-SHA384:DHE-RSA-CHACHA20-POLY1305:ECDHE-ECDSA-AES128-SHA256:ECDHE-RSA-AES128-SHA256:ECDHE-ECDSA-AES128-SHA:ECDHE-RSA-AES128-SHA:ECDHE-ECDSA-AES256-SHA384:ECDHE-RSA-AES256-SHA384:ECDHE-ECDSA-AES256-SHA:ECDHE-RSA-AES256-SHA:DHE-RSA-AES128-SHA256:DHE-RSA-AES256-SHA256:AES128-GCM-SHA256:AES256-GCM-SHA384:AES128-SHA256:AES256-SHA256:AES128-SHA:AES256-SHA:DES-CBC3-SHA \
diff --git a/setup/ssl.sh b/setup/ssl.sh
index 9bd5d539..5c36d789 100755
--- a/setup/ssl.sh
+++ b/setup/ssl.sh
@@ -28,7 +28,7 @@ source /etc/mailinabox.conf # load global vars
 if  [ ! -f /usr/bin/openssl ] \
  || [ ! -f $STORAGE_ROOT/ssl/ssl_private_key.pem ] \
  || [ ! -f $STORAGE_ROOT/ssl/ssl_certificate.pem ] \
- || [ ! -f $STORAGE_ROOT/ssl/dh2048.pem ]; then
+ || [ ! -f $STORAGE_ROOT/ssl/dh4096.pem ]; then
 	echo "Creating initial SSL certificate and perfect forward secrecy Diffie-Hellman parameters..."
 fi
 
@@ -63,7 +63,7 @@ mkdir -p $STORAGE_ROOT/ssl
 if [ ! -f $STORAGE_ROOT/ssl/ssl_private_key.pem ]; then
 	# Set the umask so the key file is never world-readable.
 	(umask 077; hide_output \
-		openssl genrsa -out $STORAGE_ROOT/ssl/ssl_private_key.pem 2048)
+		openssl genrsa -out $STORAGE_ROOT/ssl/ssl_private_key.pem 4096)
 fi
 
 # Generate a self-signed SSL certificate because things like nginx, dovecot,
@@ -92,7 +92,7 @@ fi
 
 # Generate some Diffie-Hellman cipher bits.
 # openssl's default bit length for this is 1024 bits, but we'll create
-# 2048 bits of bits per the latest recommendations.
-if [ ! -f $STORAGE_ROOT/ssl/dh2048.pem ]; then
-	openssl dhparam -out $STORAGE_ROOT/ssl/dh2048.pem 2048
+# 4096 bits of bits per the latest recommendations.
+if [ ! -f $STORAGE_ROOT/ssl/dh4096.pem ]; then
+	openssl dhparam -out $STORAGE_ROOT/ssl/dh4096.pem 4096
 fi
diff --git a/setup/system.sh b/setup/system.sh
index b7ed1317..2fb92b75 100755
--- a/setup/system.sh
+++ b/setup/system.sh
@@ -359,7 +359,7 @@ cp -f conf/fail2ban/jail.d/* /etc/fail2ban/jail.d/
 # If SSH port is not default, add the not default to the ssh jail
 if [ ! -z "$SSH_PORT" ]; then
 	# create backup copy
-	cp -f /etc/fail2ban/jail.conf jail.conf.miab_old
+	cp -f /etc/fail2ban/jail.conf /etc/fail2ban/jail.conf.miab_old
 	
 	if [ "$SSH_PORT" != "22" ]; then
 		# Add alternative SSH port