SSH on Multiple ports Fedora Core 4

[John Gallagher]

> -----Original Message-----
> From: John Gallagher [mailto:john.gallagher at ciosystems.com] 
> 
> 
> Part of my original post was that I ran this on FC1.  
> Actually it is running on FC1, however the same behavior can 
> be seen if you use the service command to start/stop the one 
> of the processes.  Apparently because the last process 
> started becomes the PID, the start, stop function of the init 
> script can effect both processes.
> 
>  /var/run/sshd.pid
>              Contains the process ID of the sshd listening 
> for connections (if
>              there are several daemons running concurrently 
> for different
>              ports, this contains the process ID of the one 
> started last).
>              The content of this file is not sensitive; it 
> can be world-read-
>              able.
> 
> Does anyone know of a way to change that behavior short of 
> compiling another binary that uses another PID?


I did some more research on this issue and figured out a work around to the
problem above.

I thought  (incorrectly) that you could define the PID File in the init
script because it has a variable for it:

PID_FILE=/var/run/sshd.pid


It turns out that the init script never sources this variable for any
purpose.  

Man of sshd_config indicated that you could add this option to change the
default pid file.  

PIDFILE /var/run/sshd-ext.pid

This in fact created a new PID, however the init script would still kill
this process.

I am not a shell scripting expert but my guess is that it was killing it
because it is doing a killproc on $SSHD -TERM where $SSHD is the path to the
executable /usr/sbin/sshd.

{
        echo -n $"Stopping $prog: "
        if [ -n "`pidfileofproc $SSHD`" ] ; then
            killproc $SSHD -TERM
        else
            failure $"Stopping $prog"
        fi
        RETVAL=$?
        [ "$RETVAL" = 0 ] && rm -f /var/lock/subsys/sshd
        echo
}

To get it working I needed to do the following:

Copy the binary in /usr/sbin/sshd to /usr/sbin/sshd-ext

Copy /etc/pam.d/sshd to /etc/pam.d/sshd-ext

Modify the init script by replacing sshd with sshd-ext:

#!/bin/bash
#
# Init file for OpenSSH server daemon
#
# chkconfig: 2345 55 25
# description: OpenSSH server daemon
#
# processname: sshd-ext
# config: /etc/ssh/ssh_host_key
# config: /etc/ssh/ssh_host_key.pub
# config: /etc/ssh/ssh_random_seed
# config: /etc/ssh/sshd_config-ext
# pidfile: /var/run/sshd-ext.pid

# source function library
. /etc/rc.d/init.d/functions

# pull in sysconfig settings
[ -f /etc/sysconfig/sshd-ext ] && . /etc/sysconfig/sshd-ext

RETVAL=0
prog="sshd-ext"

# Some functions to make the below more readable
KEYGEN=/usr/bin/ssh-keygen
SSHD=/usr/sbin/sshd-ext
RSA1_KEY=/etc/ssh/ssh_host_key
RSA_KEY=/etc/ssh/ssh_host_rsa_key
DSA_KEY=/etc/ssh/ssh_host_dsa_key
PID_FILE=/var/run/sshd-ext.pid

do_rsa1_keygen() {
        if [ ! -s $RSA1_KEY ]; then
                echo -n $"Generating SSH1 RSA host key: "
                if $KEYGEN -q -t rsa1 -f $RSA1_KEY -C '' -N '' >&/dev/null;
then
                        chmod 600 $RSA1_KEY
                        chmod 644 $RSA1_KEY.pub
                        if [ -x /sbin/restorecon ]; then
                            /sbin/restorecon $RSA1_KEY.pub
                        fi
                        success $"RSA1 key generation"
                        echo
                else
                        failure $"RSA1 key generation"
                        echo
                        exit 1
                fi
        fi
}

do_rsa_keygen() {
        if [ ! -s $RSA_KEY ]; then
                echo -n $"Generating SSH2 RSA host key: "
                if $KEYGEN -q -t rsa -f $RSA_KEY -C '' -N '' >&/dev/null;
then
                        chmod 600 $RSA_KEY
                        chmod 644 $RSA_KEY.pub
                        if [ -x /sbin/restorecon ]; then
                            /sbin/restorecon $RSA_KEY.pub
                        fi
                        success $"RSA key generation"
                        echo
                else
                        failure $"RSA key generation"
                        echo
                        exit 1
                fi
        fi
}

do_dsa_keygen() {
        if [ ! -s $DSA_KEY ]; then
                echo -n $"Generating SSH2 DSA host key: "
                if $KEYGEN -q -t dsa -f $DSA_KEY -C '' -N '' >&/dev/null;
then
                        chmod 600 $DSA_KEY
                        chmod 644 $DSA_KEY.pub
                        if [ -x /sbin/restorecon ]; then
                            /sbin/restorecon $DSA_KEY.pub
                        fi
                        success $"DSA key generation"
                        echo
                else
                        failure $"DSA key generation"
                        echo
                        exit 1
                fi
        fi
}

do_restart_sanity_check()
{
        $SSHD -t
        RETVAL=$?
        if [ ! "$RETVAL" = 0 ]; then
                failure $"Configuration file or keys are invalid"
                echo
        fi
}

start()
{
        # Create keys if necessary
        do_rsa1_keygen
        do_rsa_keygen
        do_dsa_keygen

        echo -n $"Starting $prog: "
        $SSHD $OPTIONS && success || failure
        RETVAL=$?
        [ "$RETVAL" = 0 ] && touch /var/lock/subsys/sshd-ext
        echo
}

stop()
{
        echo -n $"Stopping $prog: "
        if [ -n "`pidfileofproc $SSHD`" ] ; then
            killproc $SSHD -TERM
        else
            failure $"Stopping $prog"
        fi
        RETVAL=$?
        [ "$RETVAL" = 0 ] && rm -f /var/lock/subsys/sshd-ext
        echo
}

reload()
{
        echo -n $"Reloading $prog: "
        if [ -n "`pidfileofproc $SSHD`" ] ; then
            killproc $SSHD -HUP
        else
            failure $"Reloading $prog"
        fi
        RETVAL=$?
        echo
}

case "$1" in
        start)
                start
                ;;
        stop)
                stop
                ;;
        restart)
                stop
                start
                ;;
        reload)
                reload
                ;;
        condrestart)
                if [ -f /var/lock/subsys/sshd-ext] ; then
                        do_restart_sanity_check
                        if [ "$RETVAL" = 0 ] ; then
                                stop
                                # avoid race
                                sleep 3
                                start
                        fi
                fi
                ;;
        status)
                status $SSHD
                RETVAL=$?
                ;;
        *)
                echo $"Usage: $0
{start|stop|restart|reload|condrestart|status}"
                RETVAL=1
esac
exit $RETVAL