hosts/losurdo/unbound.nix

   1 { pkgs, lib, config, host, ... }:
   2 let
   3   inherit (config.services) unbound;
   4   inherit (config.users) users;
   5   stateDir = "/var/lib/unbound";
   6 in
   7 {
   8 networking.resolvconf.useLocalResolver = true;
   9 services.unbound = {
  10   enable = true;
  11   # DOC: https://calomel.org/unbound_dns.html
  12   settings = {
  13     remote-control = {
  14       control-enable = true;
  15       control-interface = "/run/unbound/unbound.socket";
  16     };
  17     server = {
  18       log-queries = false;
  19       verbosity = 1;
  20       interface = [
  21         "127.0.0.1"
  22         "::1"
  23       ];
  24       access-control = [
  25         "0.0.0.0/0 refuse"
  26         "::0/0 refuse"
  27         "127.0.0.0/8 allow"
  28         "::1 allow"
  29       ];
  30       prefer-ip4 = !config.networking.enableIPv6;
  31       port = 53;
  32
  33       # The file which contains the listing of primary root DNS servers.
  34       # To be updated once every six months.
  35       root-hints = "/var/lib/unbound/named.root";
  36
  37       # Do no answer id.server and hostname.bind queries.
  38       hide-identity = true;
  39       # Do not answer version.server and version.bind queries.
  40       hide-version = true;
  41
  42       # Will trust glue only if it is within the servers authority.
  43       # Harden against out of zone rrsets, to avoid spoofing attempts.
  44       # Hardening queries multiple name servers for the same data to make
  45       # spoofing significantly harder and does not mandate dnssec.
  46       harden-glue = true;
  47
  48       # Require DNSSEC data for trust-anchored zones, if such data is absent, the
  49       # zone becomes  bogus.  Harden against receiving dnssec-stripped data. If you
  50       # turn it off, failing to validate dnskey data for a trustanchor will trigger
  51       # insecure mode for that zone (like without a trustanchor).  Default on,
  52       # which insists on dnssec data for trust-anchored zones.
  53       harden-dnssec-stripped = true;
  54
  55       # Use 0x20-encoded random bits in the query to foil spoof attempts.
  56       # http://tools.ietf.org/html/draft-vixie-dnsext-dns0x20-00
  57       #
  58       # When Unbound sends a query to a remote server it sends the hostname
  59       # string in random upper and lower characters. The remote server must
  60       # resolve the hostname as if all the characters were lower case. The remote
  61       # server must then send the query back to Unbound in the same random upper
  62       # and lower characters that Unbound sent. If the characters of the hostname
  63       # in the response are in the same format as the query then the dns-0x20
  64       # check is satisfied.
  65       # Attackers hoping to poison a Unbound DNS cache must therefore guess the
  66       # mixed-case encoding of the query and the timing of the return dns answer
  67       # in addition to all other fields required in a DNS poisoning attack.
  68       # dns-0x20 increases the difficulty of the attack significantly.
  69       #
  70       # It may result in maybe 0.4% of domains getting no answers
  71       # due to no support on the authoritative server side
  72       use-caps-for-id = true;
  73
  74       #cache-min-ttl = 3600;
  75       cache-max-ttl = 86400;
  76
  77       # Perform prefetching of close to expired message cache entries.  If a client
  78       # requests the dns lookup and the TTL of the cached hostname is going to
  79       # expire in less than 10% of its TTL, unbound will (1st) return the IP of the
  80       # host to the client and (2nd) pre-fetch the DNS request from the remote DNS server.
  81       # This method has been shown to increase the amount of cached hits by
  82       # local clients by 10% on average.
  83       prefetch = true;
  84
  85       # Number of threads to create. 1 disables threading.
  86       # This should equal the number of CPU cores in the host.
  87       num-threads = host.CPUs;
  88
  89       # The number of slabs to use for cache and must be a power of 2 times the
  90       # number of num-threads set above. more slabs reduce lock contention,
  91       # but fragment memory usage.
  92       msg-cache-slabs = 8;
  93       rrset-cache-slabs = 8;
  94       infra-cache-slabs = 8;
  95       key-cache-slabs = 8;
  96
  97       # Increase the memory size of the cache. Use roughly twice as much rrset cache
  98       # memory as you use msg cache memory. Due to malloc overhead, the total memory
  99       # usage is likely to rise to double (or 2.5x) the total cache memory.
 100       rrset-cache-size = "32m";
 101       msg-cache-size = "16m";
 102
 103       # buffer size for UDP port 53 incoming (SO_RCVBUF socket option). This sets
 104       # the kernel buffer larger so that no messages are lost in spikes in the traffic.
 105       so-rcvbuf = "1m";
 106
 107       # Enforce privacy of these addresses. Strips them away from answers.
 108       # It may cause DNSSEC validation to additionally mark it as bogus.
 109       # Protects against 'DNS Rebinding' (uses browser as network proxy).
 110       #  Only 'private-domain' and 'local-data' names are allowed
 111       # to have these private addresses. No default.
 112       private-address = [
 113         "192.168.0.0/16"
 114         "172.16.0.0/12"
 115         "10.0.0.0/8"
 116       ];
 117
 118       # Allow the domain (and its subdomains) to contain private addresses.
 119       # local-data statements are allowed to contain private addresses too.
 120       #private-domain = "home.lan";
 121
 122       # If nonzero, unwanted replies are not only reported in statistics, but also
 123       # a running total is kept per thread. If it reaches the threshold, a warning
 124       # is printed and a defensive action is taken, the cache is cleared to flush
 125       # potential poison out of it.  A suggested value is 10000000, the default is
 126       # 0 (turned off). calomel.org thinks 10K is a good value.
 127       unwanted-reply-threshold = 10000;
 128
 129       # IMPORTANT FOR TESTING: If you are testing and setup NSD or BIND on
 130       # localhost you will want to allow the resolver to send queries to localhost.
 131       # Make sure to set do-not-query-localhost = true;.
 132       do-not-query-localhost = true;
 133
 134       # Should additional section of secure message also be kept clean of unsecure
 135       # data. Useful to shield the users of this validator from potential bogus
 136       # data in the additional section. All unsigned data in the additional section
 137       # is removed from secure messages.
 138       val-clean-additional = true;
 139     };
 140   };
 141 };
 142 networking.nftables.ruleset = ''
 143   table inet filter {
 144     chain output-net {
 145       meta l4proto { udp, tcp } \
 146         th dport domain \
 147         skuid ${users.unbound.name} \
 148         counter accept comment "unbound"
 149     }
 150   }
 151 '';
 152 systemd.services.unbound = {
 153   serviceConfig = {
 154     RuntimeDirectory = "unbound";
 155     RuntimeDirectoryMode = "0700";
 156   };
 157   preStart = ''
 158     install -m 444 \
 159      ${../../networking/named.root} \
 160      /var/lib/unbound/named.root
 161   '';
 162 };
 163 }