Archived
beatzaplentyandClaude Sonnet 4.6
c7bbf88dce
Check NixOS configurations / eval-hosts (pull_request) Successful in 10m30s
NixOS's dnsmasq module defaults resolveLocalQueries to true, which adds 127.0.0.1 to networking.nameservers and binds dnsmasq to listen-address=127.0.0.1. This made the host route all its own DNS through dnsmasq, which had no-resolv=true and no upstream for anything outside the tailnet domain — so every non-tailscale DNS query from the host itself (including SSSD resolving the IPA server FQDN after the IPA client module was added) failed. Setting resolveLocalQueries=false limits dnsmasq to its intended role: a forwarding proxy reachable on the LAN interface for IPA's conditional forwarder. The host uses domainControllerIp directly (already set in networking.nameservers in host.nix). Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
61 lines
2.9 KiB
Nix
61 lines
2.9 KiB
Nix
{ vars, ... }:
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{
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# Run dnsmasq on the LAN interface as a forwarding-only resolver for
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# *.ts.net (Tailscale MagicDNS names). FreeIPA's bind-dyndb-ldap
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# cannot reach 100.100.100.100 (Tailscale's internal resolver) directly
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# because the DC is not a Tailscale node. This host IS a Tailscale node
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# and can reach 100.100.100.100 via its tailscale0 interface, so it
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# acts as an intermediary: FreeIPA has a conditional forward zone for
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# ts.net pointing here (vars.tailscaleRouterIp), and this dnsmasq
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# instance forwards those queries onward to Tailscale's resolver.
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#
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# Configure FreeIPA once after deploying this host:
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# kinit admin
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# ipa dnsforwardzone-add ${vars.tailnetDomain} \
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# --forwarder=${vars.tailscaleRouterIp} \
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# --forward-policy=only
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# Note: IPA refuses to shadow ts.net (a real public TLD); use the
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# tailnet-specific subdomain (vars.tailnetDomain) instead.
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services.dnsmasq = {
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enable = true;
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# NixOS's dnsmasq module defaults resolveLocalQueries to true, which adds
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# 127.0.0.1 to networking.nameservers and makes dnsmasq bind to
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# listen-address=127.0.0.1. This instance is not the host's local
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# resolver — it only serves IPA's conditional forwarder for tailnet names.
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# The host uses domainControllerIp directly (networking.nameservers in
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# host.nix). Without this, all host DNS goes through dnsmasq, which has
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# no upstream for general queries (no-resolv=true), breaking resolution.
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resolveLocalQueries = false;
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settings = {
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# Listen only on the LAN interface — not tailscale0 or loopback.
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# bind-interfaces prevents dnsmasq from binding to 0.0.0.0 and
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# then filtering by interface later; combined with `interface` this
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# ensures it genuinely listens only on eth0.
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bind-interfaces = true;
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interface = [ vars.lxcLanInterface ];
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# Forward-only: no local /etc/hosts or /etc/resolv.conf reading,
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# no negative caching of NXDOMAIN for names this instance doesn't
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# serve. All ts.net queries come from FreeIPA's conditional forwarder
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# and must be answered by Tailscale's resolver.
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no-hosts = true;
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no-resolv = true;
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# Tailscale's internal "Quad100" resolver — reachable from any
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# Tailscale node via the tailscale0 interface. Scoped to the
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# specific tailnet subdomain (vars.tailnetDomain) rather than
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# all of ts.net: FreeIPA refuses to shadow ts.net (a real public
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# TLD with DNSimple nameservers) so the conditional forward zone
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# in FreeIPA must use the tailnet-specific subdomain instead:
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# ipa dnsforwardzone-add ${vars.tailnetDomain} \
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# --forwarder=${vars.tailscaleRouterIp} \
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# --forward-policy=only
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server = [ "/${vars.tailnetDomain}/100.100.100.100" ];
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};
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};
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networking.firewall.allowedUDPPorts = [ 53 ];
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networking.firewall.allowedTCPPorts = [ 53 ];
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}
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