79 lines
2.8 KiB
Bash
79 lines
2.8 KiB
Bash
# DNS: Configure a DNS server using nsd
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#######################################
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# This script installs packages, but the DNS zone files are only
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# created by the /dns/update API in the management server because
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# the set of zones (domains) hosted by the server depends on the
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# mail users & aliases created by the user later.
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source setup/functions.sh # load our functions
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# Install nsd, our DNS server software, and ldnsutils which helps
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# us sign zones for DNSSEC.
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# ...but first, we have to create the user because the
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# current Ubuntu forgets to do so in the .deb
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# see issue #25 and https://bugs.launchpad.net/ubuntu/+source/nsd/+bug/1311886
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if id nsd > /dev/null 2>&1; then
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true; #echo "nsd user exists... good";
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else
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useradd nsd;
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fi
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# Okay now install the packages.
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apt_install nsd ldnsutils
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# Prepare nsd's configuration.
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sudo mkdir -p /var/run/nsd
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# Create DNSSEC signing keys.
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mkdir -p "$STORAGE_ROOT/dns/dnssec";
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if [ ! -f "$STORAGE_ROOT/dns/dnssec/keys.conf" ]; then
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# These two steps take a while.
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# Create the Key-Signing Key (KSK) (-k) which is the so-called
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# Secure Entry Point. Use a NSEC3-compatible algorithm (best
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# practice), and a nice and long keylength. Use /dev/urandom
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# instead of /dev/random for noise or else we'll be waiting
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# a very long time. The domain name we provide ("_domain_")
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# doesn't matter -- we'll use the same keys for all our domains.
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KSK=$(umask 077; cd $STORAGE_ROOT/dns/dnssec; ldns-keygen -a RSASHA1-NSEC3-SHA1 -b 2048 -k -r /dev/urandom _domain_);
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# Now create a Zone-Signing Key (ZSK) which is expected to be
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# rotated more often than a KSK, although we have no plans to
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# rotate it (and doing so would be difficult to do without
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# disturbing DNS availability.) Omit '-k' and use a shorter key.
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ZSK=$(umask 077; cd $STORAGE_ROOT/dns/dnssec; ldns-keygen -a RSASHA1-NSEC3-SHA1 -b 1024 -r /dev/urandom _domain_);
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# These generate two sets of files like:
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# K_domain_.+007+08882.ds <- DS record for adding to NSD configuration files
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# K_domain_.+007+08882.key <- public key (goes into DS record & upstream DNS provider like your registrar)
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# K_domain_.+007+08882.private <- private key (secret!)
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# The filenames are unpredictable and encode the key generation
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# options. So we'll store the names of the files we just generated.
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# We might have multiple keys down the road. This will identify
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# what keys are the current keys.
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cat > $STORAGE_ROOT/dns/dnssec/keys.conf << EOF;
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KSK=$KSK
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ZSK=$ZSK
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EOF
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fi
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# Force the dns_update script to be run every day to re-sign zones for DNSSEC.
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cat > /etc/cron.daily/mailinabox-dnssec << EOF;
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#!/bin/bash
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# Mail-in-a-Box
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# Re-sign any DNS zones with DNSSEC because the signatures expire periodically.
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curl -d GO http://localhost:10222/dns/update
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EOF
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chmod +x /etc/cron.daily/mailinabox-dnssec
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# Permit DNS queries on TCP/UDP in the firewall.
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ufw_allow domain
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