Create a tunnel for email service, e.g. to get POP/IMAP through outbound port filters

email-tunnel

#!/bin/sh
#
# email-tunnel - create a tunnel for email service, e.g. to get POP/IMAP through outbound port filters
#
# Prerequisites: daemon, ssh
#
# Uses the LocalForward feature of ssh.
#
# You'll need an "email-tunnel" entry in your .ssh/config file. Something like:
#
#     Host            email-tunnel
#       HostName	  shell.soaustin.net
#       User            chip
#       LocalForward	  4143 mail.soaustin.net:143
#
# Chip Rosenthal
# chip@unicom.com
#

set -e

USAGE="usage: $0 {start|stop|restart|status} (default = \"start\")"

NAME=`basename $0`

PIDFILE=$HOME/var/run/$NAME.pid
mkdir -p `dirname $PIDFILE`

LOGFILE=$HOME/var/log/$NAME.log
mkdir -p `dirname $LOGFILE`


perform_start()
{
    if perform_check ; then
        echo "ERROR - service \"$NAME\" is already running" >&2
        return 1
    fi
    echo "Starting service \"$NAME\" ..." >&2
    daemon \
        --name=$NAME \
        --pidfile=$PIDFILE \
        --errlog=$LOGFILE \
        --output=$LOGFILE \
        --respawn \
        -- \
        ssh -N -v email-tunnel
}


perform_stop()
{
    if perform_check ; then
            : nop
    else
        echo "ERROR - service \"$NAME\" is not running" >&2
        return 1
    fi
    echo "Stopping service \"$NAME\" ..." >&2
    daemon \
        --name=$NAME \
        --pidfile=$PIDFILE \
        --stop
}


perform_check()
{
    daemon \
        --name=$NAME \
        --pidfile=$PIDFILE \
        --running
}


perform_status()
{
    daemon \
        --name=$NAME \
        --pidfile=$PIDFILE \
        --verbose=99 --running
}

case $# in
0) op="start" ;;
1) op="$1" ;;
*) echo "$USAGE" >&2 ; exit 1
esac

case "$op" in

start)
    perform_start
    ;;

stop)
    perform_stop
    ;;

status)
    perform_status
    exit 0 # to skip final message
    ;;

restart)
    if perform_check ; then
        perform_stop
        sleep 3
    else
        echo "Service \"$NAME\" currently is not running." >&2
    fi
    perform_start
    ;;

*)
    echo "$USAGE" >&2
    exit 1
    ;;

esac

if perform_check ; then
    echo "Service \"$NAME\" is running." >&2
else
    echo "Service \"$NAME\" is stopped" >&2
fi