From f6347bfc9e2a597713b2f2758a2cc19214a1cc87 Mon Sep 17 00:00:00 2001
From: Ian Kelling <iank@fsf.org>
Date: Mon, 13 May 2019 10:49:47 -0400
Subject: [PATCH] notes about ipv6

---
 switch-mail-host | 34 +++++++++++++---------------------
 1 file changed, 13 insertions(+), 21 deletions(-)

diff --git a/switch-mail-host b/switch-mail-host
index b6423e0..0cc8c0b 100755
--- a/switch-mail-host
+++ b/switch-mail-host
@@ -65,15 +65,6 @@ if [[ ! $new_host || ! $old_host ]]; then
   exit 1
 fi
 
-# TODO: make home dns use ipv6. for work, make a cronjob that updates
-# the dns there.
-#
-# This exists because if mail_host is on the home network with a vpn
-# tunnel, and another host on the home network tries to connect to the
-# public tunnel ip, it won't work because from the public machine's
-# perspective, due to nat, both home network machines have the same
-# ip. We could solve this by using ipv6 addresses, but not all networks
-# i'm on with more than one machine are ipv6 enabled.
 at_home=false
 if timeout -s 9 5 ssh-keyscan -p 2220 -t rsa 10.0.0.1 2>/dev/null | grep -qFx '[10.0.0.1]:2220 ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQCH+/h1dGEfKEusBblndU2e6QT4wLCm5+yqr/sqh/0X9YfjR7BfWWm8nNmuP55cYc+Wuf5ljB1H1acXEcsl1y8e0j3agHfF0V74FE1N1zz5nn2Ep8NHnmqgEhza38ZxMPh+4p3X7zklEKU7+3SzybKBi8sg0wLzlS2LM0JaUN80zR2sK11Kye3dURUXPk78u5wodOkgcEYRwSYaDMJlUzWP+poRXIDJwFaMQnwmxbl/c84yOyaU0x/d6hFwoRscWecihX+vvBNeSyxR4xr2HDOyUWwJkctyAgt2p7w3tfkXOKcCRzTAjGVIMQLTvo0sG/yJbcyHoEFdFybCsgDvfyYn'; then
   at_home=true
@@ -132,18 +123,19 @@ if mountpoint -q /m; then sudo umount /m; fi
 if mountpoint -q /o; then sudo umount /o; fi
 EOF
 
-# if new_host is not on home network, make mail.iankelling.org not resolve
-# on the home network.
-if [[ $new_host == $HOSTNAME ]] && ! $at_home; then
-  echo | $wrt_shell cedit mail_host /etc/hosts || [[ $? == 1 ]] # 1 means file changed.
-else
-  $wrt_shell bash -xs $new_host <<'EOFOUTER'
-new_host=$1
-cedit mail_host /etc/hosts <<EOF || /etc/init.d/dnsmasq restart
-$(grep "\b$new_hostname\b" /etc/hosts | awk '{print $1}') mail.iankelling.org
-EOF
-EOFOUTER
-fi
+# previously, I was checking to see if the new mail host
+# is on my home network, then changing my home dns
+# to resolve on the local network, so that I didnt
+# have to send traffic out to the internet or rely
+# on that. However, that breaks for a laptop that roams.
+# So, we could have a cronjob that updates that dns,
+# however, another solution is to just use ipv6,
+# and I prefer that.
+#
+# TODO: enable ipv6 for email. exim config setting disables it.
+# need to add vpn support. need to add firewall / routing.
+# I think exim will try ipv6 first, so no need to disable
+# ipv6 i think.
 
 $old_shell primary-setup $new_hostname
 
-- 
2.30.2