From 709a36a78bd13e0244ab254834ff67d0c03a6f45 Mon Sep 17 00:00:00 2001 From: Ian Kelling Date: Mon, 19 Feb 2018 17:17:08 -0500 Subject: [PATCH] make mail-route idempotent --- mail-route | 53 +++++++++++++++++++++++++++++++++++++++-------------- 1 file changed, 39 insertions(+), 14 deletions(-) diff --git a/mail-route b/mail-route index 95cbf8d..ab26a13 100755 --- a/mail-route +++ b/mail-route @@ -35,6 +35,8 @@ if (( $# != 1 )); then fi start() { + start=true + stop=false iptables_op=-A ip_op=add # systemd around stretch release time, would wait until openvpn actually connected, @@ -52,15 +54,20 @@ start() { echo "$0: error: timeout waiting for valid tun_dev, currently:$tun_dev" exit 1 fi - e() { "$@"; } + e() { echo "$0: $*"; "$@"; } _errcatch_cleanup=stop modify + # we leave it as is even when stopping, because we would like it to be default, but the only way + # to change the default is for every device, and I want to avoid that, even though I wouldn't mind, others users of this script might. + e sysctl net.ipv4.conf.$tun_dev.rp_filter=2 } stop() { + start=false + stop=true iptables_op=-D ip_op=del - tun_dev=$(iptables -t nat -S | sed -rn "s/^-A POSTROUTING -o (tun[[:digit:]]+) -m mark --mark 0x1 -j SNAT --to-source 10.8.0.4$/\1/p"|head -n1) || printf "failed to find tun device.\n" - e() { "$@" || printf "maybe ok failure: %s\n" "$*"; } + tun_dev=$(ip a show to 10.8.0.4/24 | sed -rn '1s/^\S+\s+([^:]+).*/\1/p') + e() { echo "$0: $*"; "$@" || printf "maybe ok failure: %s\n" "$*"; } modify } @@ -80,30 +87,48 @@ show() { exit 0 } +runtest() { + # debugging: + #echo start=$start stop=$stop exists=$exists + { $start && ! $exists; } || { $stop && $exists; } +} + +iptmod() { #iptables modify + local check cmd="$*" exists=true + ${cmd/-[AD]/-C} &>/dev/null || exists=false + if runtest; then e $cmd; fi +} # code common to start and stop. modify() { # match source or dest port. note, when we send to a port, it picks a random high port as # the source. for port in 25 143; do # smtp and imap. - e iptables -t mangle $iptables_op \ - OUTPUT -m tcp -p tcp -m multiport --ports $port -j MARK --set-mark 0x1 - e iptables -t mangle $iptables_op \ - OUTPUT -m tcp -p tcp -m multiport --ports $port -j MARK --set-mark 0x0 \ - -d 10.0.0.0/8,172.16.0.0/12,192.168.0.0/16 + iptcommon="OUTPUT -m tcp -p tcp -m multiport --ports $port -j MARK --set-mark" + iptmod iptables -t mangle $iptables_op $iptcommon 0x1 + iptmod iptables -t mangle $iptables_op $iptcommon 0x0 -d 10.0.0.0/8,172.16.0.0/12,192.168.0.0/16 # note, we could have used a custom chain and returned instead of setting the mark again. # in case anyone was ever curious, the inverse of private ips is: #0.0.0.0/5,8.0.0.0/7,11.0.0.0/8,12.0.0.0/6,16.0.0.0/4,32.0.0.0/3,64.0.0.0/2,128.0.0.0/3,160.0.0.0/5,168.0.0.0/6,172.0.0.0/12,172.32.0.0/11,172.64.0.0/10,172.128.0.0/9,173.0.0.0/8,174.0.0.0/7,176.0.0.0/4,192.0.0.0/9,192.128.0.0/11,192.160.0.0/13,192.169.0.0/16,192.170.0.0/15,192.172.0.0/14,192.176.0.0/12,192.192.0.0/10,193.0.0.0/8,194.0.0.0/7,196.0.0.0/6,200.0.0.0/5,208.0.0.0/4,224.0.0.0/3 - done - e iptables -t nat $iptables_op POSTROUTING -o $tun_dev -m mark --mark 0x1 -j SNAT --to-source 10.8.0.4 - e ip rule $ip_op fwmark 1 table 1 - # note, this rule does not persist when the tun interface is deleted - e ip route $ip_op default via 10.8.0.1 table 1 + + if [[ $tun_dev ]]; then + # when $tun_dev goes away, so does this rul + iptmod iptables -t nat $iptables_op POSTROUTING -o $tun_dev -m mark --mark 0x1 -j SNAT --to-source 10.8.0.4 + fi + + + iprulecmd="fwmark 1 table 1" + exists=true; ip rule show $iprulecmd | grep . &>/dev/null || exists=false + if runtest; then e ip rule $ip_op $iprulecmd; fi + + iproutecmd="default via 10.8.0.1 table 1" + exists=true; ip route show $iproutecmd | grep . &>/dev/null || exists=false + if runtest; then e ip route $ip_op $iproutecmd; fi # on debian this is 0 (no filter), on ubuntu it\'s 1, which is no good. 0 or 2 both work fine. # 2 drops it if the packet is not routable, martian address, or my default route is screwed up, # so, eh, might as well. some rhel docs recommend using it. - e sysctl net.ipv4.conf.$tun_dev.rp_filter=2 + exit 0 } -- 2.30.2