I use a Linksys WRT54GL router with DD-WRT v24-sp2 (10/10/09) std (SVN revision 13064) which I am trying to make forward all HTTP and HTTPS traffic to an external app called Fiddler (used as proxy) on port 8888.

After a lot of digging on this site, dd-wrt forum, dd-wrt.com and WWW, I am stacked with the following piece of code that works (thanks to the guys from dd-wrt support for this info), but only for forwarding HTTP traffic (port 80):

#!/bin/sh
PROXY_IP=1234567890
PROXY_PORT=8888
LAN_IP=`nvram get lan_ipaddr`
LAN_NET=$LAN_IP/`nvram get lan_netmask`

iptables -t nat -A PREROUTING -i br0 -s $LAN_NET -d $LAN_NET -p tcp --dport 80 -j ACCEPT
iptables -t nat -A PREROUTING -i br0 -s ! $PROXY_IP -p tcp --dport 80 -j DNAT --to $PROXY_IP:$PROXY_PORT
iptables -t nat -I POSTROUTING -o br0 -s $LAN_NET -d $PROXY_IP -p tcp -j SNAT --to $LAN_IP
iptables -I FORWARD -i br0 -o br0 -s $LAN_NET -d $PROXY_IP -p tcp --dport $PROXY_PORT -j ACCEPT

I tried to edit the code from above and I came up with the following but it's still not forwarding HTTPS but just HTTP traffic:

#!/bin/sh
PROXY_IP=1234567890
PROXY_PORT=8888
LAN_IP=`nvram get lan_ipaddr`
LAN_NET=$LAN_IP/`nvram get lan_netmask`
iptables -t nat -A PREROUTING -i br0 -s $LAN_NET -d $LAN_NET -p tcp -m multiport --dports 80,443 -j ACCEPT
iptables -t nat -A PREROUTING -i br0 -s ! $PROXY_IP -p tcp -m multiport --dports 80,443 -j DNAT --to $PROXY_IP:$PROXY_PORT
iptables -t nat -I POSTROUTING -o br0 -s $LAN_NET -d $PROXY_IP -p tcp -j SNAT --to $LAN_IP
iptables -I FORWARD -i br0 -o br0 -s $LAN_NET -d $PROXY_IP -p tcp --dport $PROXY_PORT -j ACCEPT

I am not sure if is possible to forward HTTPS traffic anymore by just using a router so I'd appreciate if somebody will share his thoughts and/or examples regarding this subject here.

Thanks!