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[sourcephile-nix.git] / hosts / mermet / 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 # Avoid: warning: so-rcvbuf 1048576 was not granted. Got 425984.
10 # To fix: start with root permissions(linux)
11 # or sysctl bigger net.core.rmem_max(linux)
12 # or kern.ipc.maxsockbuf(bsd) values.
13 boot.kernel.sysctl."net.core.rmem_max" = 1048576;
14 services.unbound = {
15 enable = true;
16 # DOC: https://calomel.org/unbound_dns.html
17 settings = {
18 remote-control = {
19 control-enable = true;
20 control-interface = "/run/unbound/unbound.socket";
21 };
22 server = {
23 log-queries = false;
24 verbosity = 1;
25 interface = [ "127.0.0.1" "::1" ];
26 prefer-ip4 = !config.networking.enableIPv6;
27 port = 53;
28
29 # The file which contains the listing of primary root DNS servers.
30 # To be updated once every six months.
31 root-hints = "/var/lib/unbound/named.root";
32
33 # Do no answer id.server and hostname.bind queries.
34 hide-identity = true;
35 # Do not answer version.server and version.bind queries.
36 hide-version = true;
37
38 # Will trust glue only if it is within the servers authority.
39 # Harden against out of zone rrsets, to avoid spoofing attempts.
40 # Hardening queries multiple name servers for the same data to make
41 # spoofing significantly harder and does not mandate dnssec.
42 harden-glue = true;
43
44 # Require DNSSEC data for trust-anchored zones, if such data is absent, the
45 # zone becomes bogus. Harden against receiving dnssec-stripped data. If you
46 # turn it off, failing to validate dnskey data for a trustanchor will trigger
47 # insecure mode for that zone (like without a trustanchor). Default on,
48 # which insists on dnssec data for trust-anchored zones.
49 harden-dnssec-stripped = true;
50
51 # Use 0x20-encoded random bits in the query to foil spoof attempts.
52 # http://tools.ietf.org/html/draft-vixie-dnsext-dns0x20-00
53 #
54 # When Unbound sends a query to a remote server it sends the hostname
55 # string in random upper and lower characters. The remote server must
56 # resolve the hostname as if all the characters were lower case. The remote
57 # server must then send the query back to Unbound in the same random upper
58 # and lower characters that Unbound sent. If the characters of the hostname
59 # in the response are in the same format as the query then the dns-0x20
60 # check is satisfied.
61 # Attackers hoping to poison a Unbound DNS cache must therefore guess the
62 # mixed-case encoding of the query and the timing of the return dns answer
63 # in addition to all other fields required in a DNS poisoning attack.
64 # dns-0x20 increases the difficulty of the attack significantly.
65 #
66 # It may result in maybe 0.4% of domains getting no answers
67 # due to no support on the authoritative server side
68 use-caps-for-id = true;
69
70 #cache-min-ttl = 3600;
71 cache-max-ttl = 86400;
72
73 # Perform prefetching of close to expired message cache entries. If a client
74 # requests the dns lookup and the TTL of the cached hostname is going to
75 # expire in less than 10% of its TTL, unbound will (1st) return the IP of the
76 # host to the client and (2nd) pre-fetch the DNS request from the remote DNS server.
77 # This method has been shown to increase the amount of cached hits by
78 # local clients by 10% on average.
79 prefetch = true;
80
81 # Number of threads to create. 1 disables threading.
82 # This should equal the number of CPU cores in the host.
83 num-threads = host.CPUs;
84
85 # The number of slabs to use for cache and must be a power of 2 times the
86 # number of num-threads set above. more slabs reduce lock contention,
87 # but fragment memory usage.
88 msg-cache-slabs = 8;
89 rrset-cache-slabs = 8;
90 infra-cache-slabs = 8;
91 key-cache-slabs = 8;
92
93 # Increase the memory size of the cache. Use roughly twice as much rrset cache
94 # memory as you use msg cache memory. Due to malloc overhead, the total memory
95 # usage is likely to rise to double (or 2.5x) the total cache memory.
96 rrset-cache-size = "32m";
97 msg-cache-size = "16m";
98
99 # buffer size for UDP port 53 incoming (SO_RCVBUF socket option). This sets
100 # the kernel buffer larger so that no messages are lost in spikes in the traffic.
101 so-rcvbuf = "1m";
102
103 # Enforce privacy of these addresses. Strips them away from answers.
104 # It may cause DNSSEC validation to additionally mark it as bogus.
105 # Protects against 'DNS Rebinding' (uses browser as network proxy).
106 # Only 'private-domain' and 'local-data' names are allowed
107 # to have these private addresses. No default.
108 private-address = [
109 "192.168.0.0/16"
110 "172.16.0.0/12"
111 "10.0.0.0/8"
112 ];
113
114 # Allow the domain (and its subdomains) to contain private addresses.
115 # local-data statements are allowed to contain private addresses too.
116 #private-domain = "home.lan";
117
118 # If nonzero, unwanted replies are not only reported in statistics, but also
119 # a running total is kept per thread. If it reaches the threshold, a warning
120 # is printed and a defensive action is taken, the cache is cleared to flush
121 # potential poison out of it. A suggested value is 10000000, the default is
122 # 0 (turned off). calomel.org thinks 10K is a good value.
123 unwanted-reply-threshold = 10000;
124
125 # IMPORTANT FOR TESTING: If you are testing and setup NSD or BIND on
126 # localhost you will want to allow the resolver to send queries to localhost.
127 # Make sure to set do-not-query-localhost = true;.
128 do-not-query-localhost = true;
129
130 # Should additional section of secure message also be kept clean of unsecure
131 # data. Useful to shield the users of this validator from potential bogus
132 # data in the additional section. All unsigned data in the additional section
133 # is removed from secure messages.
134 val-clean-additional = true;
135 };
136 };
137 };
138 networking.nftables.ruleset = ''
139 add rule inet filter fw2net tcp dport 53 skuid ${users.unbound.name} counter accept comment "Unbound"
140 add rule inet filter fw2net udp dport 53 skuid ${users.unbound.name} counter accept comment "Unbound"
141 '';
142 systemd.services.unbound = {
143 serviceConfig = {
144 RuntimeDirectory = "unbound";
145 RuntimeDirectoryMode = "0700";
146 };
147 preStart = ''
148 install -m 444 \
149 ${../../networking/named.root} \
150 /var/lib/unbound/named.root
151 '';
152 };
153 }