[luau] Port Forwarding 2.4 kernel (RH 7.3)

[MonMotha]

Mike Ballon wrote:
> Thanks in advance....
> 
> So yet again something that I liked and knew quite well changed, I can't
> port forward with the 2.4 kernel is save my life.  I like my old fw script
> it works great (minus forwarding now) so I disabled the ipchains and
> iptables init script after spending three hours pulling my hair out and use
> my old script as of now.  All I want is simple port forwarding like I had
> with ipmasqadm, help me out.
> 
> I want the following rule (I'll do the rest) ported to whatever the heck
> works now if someone has a spare minute or two.  I'm running the stock RH
> 7.3 2.4.18-3 kernel.
> 
> $IPCHAINS -A input -i $ExtIF -p tcp -s 0/0 -d $ExtHostIP 25 -j ACCEPT
> ipmasqadm portfw -a -P tcp -L $ExtHostIP 25 -R 192.168.0.5 25
> 
> Thanks oh here's the var's in case you want them, it's pretty much the same
> as the one I demo'd at one of the luau mettings way back.
> 
> # Setup global variables here
> IPCHAINS="/sbin/ipchains"
> 
> # Setup Internal LAN variables here
> IntIF="eth1"
> IntHostIP=`ifconfig eth1 | grep inet | awk -F: '{ print $2}' |awk -F" "
> '{print $1}'`
> 
> # Setup External Internet variables here
> ExtIF="eth0"
> ExtHostIP=`ifconfig eth0 | grep inet | awk -F: '{ print $2}' |awk -F" "
> '{print $1}'`

Unfortunately, 2.4 can't use ipmasqadm, and ipchains can't do port 
forwards on it's own, so you'll have to use iptables for this.  Of 
course this means converting whatever rulesets you might have (which may 
be a problem).

However, iptables is pretty flexible.  To forward a port:
iptables -t nat -A PREROUTING -p tcp -s $ExtHostIP --dport 25 --to 
192.168.0.5:25

Make sure you allow it on the forward table.

--MonMotha