hosts/losurdo/unbound.nix

   1 { config, host, ... }:
   2 let
   3   inherit (config.services) unbound;
   4   inherit (config.users) users;
   5 in
   6 {
   7   networking.resolvconf.useLocalResolver = true;
   8   services.resolved.enable = false;
   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 }