make local SMTP connections able to reach containerized Exim even when using the external IP address

1 files changed, 17 insertions, 0 deletions

diff --git a/guix-container.sh b/guix-container.sh
index d117ae3..411e4ff 100755
--- a/guix-container.sh
+++ b/guix-container.sh
@@ -87,6 +87,13 @@ is_running() {
     return $?
 }
 
+resolve_ipv4_domain() {
+    guix shell glibc -- getent ahosts "$1" |
+        grep -E '^([0-9]+\.){3}[0-9]+[[:space:]]+STREAM' |
+        head -1 |
+        awk '{print $1}'
+}
+
 network_setup() {
     SHEPHERD_PID="$1"
 
@@ -117,6 +124,11 @@ network_setup() {
                  -j DNAT --to-destination 10.207.87.2
     done
 
+    iptables -t nat -A OUTPUT                              \
+             -d "$(resolve_ipv4_domain koszko.org)" -p tcp \
+             -m multiport --dports 25,12525,465,587        \
+             -j DNAT --to-destination 10.207.87.2
+
     cat /etc/resolv.conf |
         nsenter --target "$SHEPHERD_PID" --all \
                 /run/current-system/profile/bin/tee /etc/resolv.conf > /dev/null
@@ -150,6 +162,11 @@ network_rip() {
                           -s 10.207.87.1/24 -o "$LINKNAME" \
                           -j MASQUERADE
     done
+
+    iptables_rip_rule -t nat -D OUTPUT                              \
+                      -d "$(resolve_ipv4_domain koszko.org)" -p tcp \
+                      -m multiport --dports 25,12525,465,587        \
+                      -j DNAT --to-destination 10.207.87.2
 }
 
 stop() {