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heather: SNAT Docker egress to AstrNet identity and allow replies

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heather 2026-09-27 00:17:03 +00:00
commit b014c03b21
1 changed files with 9 additions and 1 deletions
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hosts/heather/astrnet.nix
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@ -83,7 +83,7 @@ in {
# WireGuard peers use allowedIPs 0/0 as an ACL, so do not rely on a packet's # WireGuard peers use allowedIPs 0/0 as an ACL, so do not rely on a packet's
# source address to identify a particular AstrNet client here. # source address to identify a particular AstrNet client here.
systemd.services.astrnet-guard = { systemd.services.astrnet-guard = {
description = "Allow AstrNet host ingress; block AstrNet transit"; description = "Allow AstrNet ingress and Docker replies; block new transit";
wantedBy = [ "multi-user.target" ]; wantedBy = [ "multi-user.target" ];
requiredBy = [ "wireguard-wg-mic-der.service" "wireguard-wg-mic-bd8.service" ]; requiredBy = [ "wireguard-wg-mic-der.service" "wireguard-wg-mic-bd8.service" ];
before = [ "wireguard-wg-mic-der.service" "wireguard-wg-mic-bd8.service" ]; before = [ "wireguard-wg-mic-der.service" "wireguard-wg-mic-bd8.service" ];
@ -102,8 +102,16 @@ in {
} }
chain forward { chain forward {
type filter hook forward priority -150; policy accept; type filter hook forward priority -150; policy accept;
# Only replies to Docker-initiated connections, never new mesh transit.
iifname { "wg-mic-der", "wg-mic-bd8" } ct state established,related accept
iifname { "wg-mic-der", "wg-mic-bd8" } drop iifname { "wg-mic-der", "wg-mic-bd8" } drop
} }
chain postrouting {
type nat hook postrouting priority 99; policy accept;
# Docker's own MASQUERADE would use the tunnel transit IP, which
# AstrNet exits do not NAT. Use the advertised mesh identity instead.
oifname { "wg-mic-der", "wg-mic-bd8" } ip saddr { 172.17.0.0/16, 172.18.0.0/16, 172.19.0.0/16 } snat to ${id4}
}
} }
RULES RULES
''; '';