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hosts/common: use servo-style dns on all machines

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it'll be handy as i want to place individual applications inside VPNs/namespaces
This commit is contained in:
Colin 2024-01-15 01:16:22 +00:00
parent a7964c4f0c
commit 5b9c58dbc6
3 changed files with 38 additions and 35 deletions
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35
hosts/by-name/servo/net.nix
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@ -42,41 +42,6 @@ in
# "9.9.9.9"
# ];
# use systemd's stub resolver.
# /etc/resolv.conf isn't sophisticated enough to use different servers per net namespace (or link).
# instead, running the stub resolver on a known address in the root ns lets us rewrite packets
# in the ovnps namespace to use the provider's DNS resolvers.
# a weakness is we can only query 1 NS at a time (unless we were to clone the packets?)
# there also seems to be some cache somewhere that's shared between the two namespaces.
# i think this is a libc thing. might need to leverage proper cgroups to _really_ kill it.
# - getent ahostsv4 www.google.com
# - try fix: <https://serverfault.com/questions/765989/connect-to-3rd-party-vpn-server-but-dont-use-it-as-the-default-route/766290#766290>
services.resolved.enable = true;
# without DNSSEC:
# - dig matrix.org => works
# - curl https://matrix.org => works
# with default DNSSEC:
# - dig matrix.org => works
# - curl https://matrix.org => fails
# i don't know why. this might somehow be interfering with the DNS run on this device (trust-dns)
services.resolved.dnssec = "false";
networking.nameservers = [
# use systemd-resolved resolver
# full resolver (which understands /etc/hosts) lives on 127.0.0.53
# stub resolver (just forwards upstream) lives on 127.0.0.54
"127.0.0.53"
];
# nscd -- the Name Service Caching Daemon -- caches DNS query responses
# in a way that's unaware of my VPN routing, so routes are frequently poor against
# services which advertise different IPs based on geolocation.
# nscd claims to be usable without a cache, but in practice i can't get it to not cache!
# nsncd is the Name Service NON-Caching Daemon. it's a drop-in that doesn't cache;
# this is OK on the host -- because systemd-resolved caches. it's probably sub-optimal
# in the netns and we query upstream DNS more often than needed. hm.
# TODO: run a separate recursive resolver in each namespace.
services.nscd.enableNsncd = true;
# services.resolved.extraConfig = ''
# # docs: `man resolved.conf`
# # DNS servers to use via the `wg-ovpns` interface.

1
hosts/common/net/default.nix
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@ -2,6 +2,7 @@
{
imports = [
./dns.nix
./hostnames.nix
./upnp.nix
./vpn.nix

37
hosts/common/net/dns.nix Normal file
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@ -0,0 +1,37 @@
{ ... }:
{
# use systemd's stub resolver.
# /etc/resolv.conf isn't sophisticated enough to use different servers per net namespace (or link).
# instead, running the stub resolver on a known address in the root ns lets us rewrite packets
# in the ovnps namespace to use the provider's DNS resolvers.
# a weakness is we can only query 1 NS at a time (unless we were to clone the packets?)
# there also seems to be some cache somewhere that's shared between the two namespaces.
# i think this is a libc thing. might need to leverage proper cgroups to _really_ kill it.
# - getent ahostsv4 www.google.com
# - try fix: <https://serverfault.com/questions/765989/connect-to-3rd-party-vpn-server-but-dont-use-it-as-the-default-route/766290#766290>
services.resolved.enable = true;
# without DNSSEC:
# - dig matrix.org => works
# - curl https://matrix.org => works
# with default DNSSEC:
# - dig matrix.org => works
# - curl https://matrix.org => fails
# i don't know why. this might somehow be interfering with the DNS run on this device (trust-dns)
services.resolved.dnssec = "false";
networking.nameservers = [
# use systemd-resolved resolver
# full resolver (which understands /etc/hosts) lives on 127.0.0.53
# stub resolver (just forwards upstream) lives on 127.0.0.54
"127.0.0.53"
];
# nscd -- the Name Service Caching Daemon -- caches DNS query responses
# in a way that's unaware of my VPN routing, so routes are frequently poor against
# services which advertise different IPs based on geolocation.
# nscd claims to be usable without a cache, but in practice i can't get it to not cache!
# nsncd is the Name Service NON-Caching Daemon. it's a drop-in that doesn't cache;
# this is OK on the host -- because systemd-resolved caches. it's probably sub-optimal
# in the netns and we query upstream DNS more often than needed. hm.
# TODO: run a separate recursive resolver in each namespace.
services.nscd.enableNsncd = true;
}