Files
start-os/build/lib/scripts/forward-port
Aiden McClelland 4527046f2e feat: NAT hairpinning, DNS static servers, clear service error on install
- Add POSTROUTING MASQUERADE rules for container and host hairpin NAT
- Allow bridge subnet containers to reach private forwards via LAN IPs
- Pass bridge_subnet env var from forward.rs to forward-port script
- Use DB-configured static DNS servers in resolver with DB watcher
- Fall back to resolv.conf servers when no static servers configured
- Clear service error state when install/update completes successfully
- Remove completed TODO items
2026-02-19 15:27:52 -07:00

73 lines
3.5 KiB
Bash
Executable File

#!/bin/bash
if [ -z "$sip" ] || [ -z "$dip" ] || [ -z "$dprefix" ] || [ -z "$sport" ] || [ -z "$dport" ]; then
>&2 echo 'missing required env var'
exit 1
fi
NAME="F$(echo "$sip:$sport -> $dip/$dprefix:$dport ${src_subnet:-any}" | sha256sum | head -c 15)"
for kind in INPUT FORWARD ACCEPT; do
if ! iptables -C $kind -j "${NAME}_${kind}" 2> /dev/null; then
iptables -N "${NAME}_${kind}" 2> /dev/null
iptables -A $kind -j "${NAME}_${kind}"
fi
done
for kind in PREROUTING OUTPUT POSTROUTING; do
if ! iptables -t nat -C $kind -j "${NAME}_${kind}" 2> /dev/null; then
iptables -t nat -N "${NAME}_${kind}" 2> /dev/null
iptables -t nat -A $kind -j "${NAME}_${kind}"
fi
done
err=0
trap 'err=1' ERR
for kind in INPUT FORWARD ACCEPT; do
iptables -F "${NAME}_${kind}" 2> /dev/null
done
for kind in PREROUTING OUTPUT POSTROUTING; do
iptables -t nat -F "${NAME}_${kind}" 2> /dev/null
done
if [ "$UNDO" = 1 ]; then
conntrack -D -p tcp -d $sip --dport $sport || true # conntrack returns exit 1 if no connections are active
conntrack -D -p udp -d $sip --dport $sport || true # conntrack returns exit 1 if no connections are active
exit $err
fi
# DNAT: rewrite destination for incoming packets (external traffic)
# When src_subnet is set, only forward traffic from that subnet (private forwards)
if [ -n "$src_subnet" ]; then
iptables -t nat -A ${NAME}_PREROUTING -s "$src_subnet" -d "$sip" -p tcp --dport "$sport" -j DNAT --to-destination "$dip:$dport"
iptables -t nat -A ${NAME}_PREROUTING -s "$src_subnet" -d "$sip" -p udp --dport "$sport" -j DNAT --to-destination "$dip:$dport"
# Also allow containers on the bridge subnet to reach this forward
if [ -n "$bridge_subnet" ]; then
iptables -t nat -A ${NAME}_PREROUTING -s "$bridge_subnet" -d "$sip" -p tcp --dport "$sport" -j DNAT --to-destination "$dip:$dport"
iptables -t nat -A ${NAME}_PREROUTING -s "$bridge_subnet" -d "$sip" -p udp --dport "$sport" -j DNAT --to-destination "$dip:$dport"
fi
else
iptables -t nat -A ${NAME}_PREROUTING -d "$sip" -p tcp --dport "$sport" -j DNAT --to-destination "$dip:$dport"
iptables -t nat -A ${NAME}_PREROUTING -d "$sip" -p udp --dport "$sport" -j DNAT --to-destination "$dip:$dport"
fi
# DNAT: rewrite destination for locally-originated packets (hairpin from host itself)
iptables -t nat -A ${NAME}_OUTPUT -d "$sip" -p tcp --dport "$sport" -j DNAT --to-destination "$dip:$dport"
iptables -t nat -A ${NAME}_OUTPUT -d "$sip" -p udp --dport "$sport" -j DNAT --to-destination "$dip:$dport"
# Allow new connections to be forwarded to the destination
iptables -A ${NAME}_FORWARD -d $dip -p tcp --dport $dport -m state --state NEW -j ACCEPT
iptables -A ${NAME}_FORWARD -d $dip -p udp --dport $dport -m state --state NEW -j ACCEPT
# NAT hairpin: masquerade traffic from the bridge subnet or host to the DNAT
# target, so replies route back through the host for proper NAT reversal.
# Container-to-container hairpin (source is on the bridge subnet)
if [ -n "$bridge_subnet" ]; then
iptables -t nat -A ${NAME}_POSTROUTING -s "$bridge_subnet" -d "$dip" -p tcp --dport "$dport" -j MASQUERADE
iptables -t nat -A ${NAME}_POSTROUTING -s "$bridge_subnet" -d "$dip" -p udp --dport "$dport" -j MASQUERADE
fi
# Host-to-container hairpin (host connects to its own gateway IP, source is sip)
iptables -t nat -A ${NAME}_POSTROUTING -s "$sip" -d "$dip" -p tcp --dport "$dport" -j MASQUERADE
iptables -t nat -A ${NAME}_POSTROUTING -s "$sip" -d "$dip" -p udp --dport "$dport" -j MASQUERADE
exit $err