I am trying to forward port 443 to a different server using iptables. What can explain this not working? I've enabled net.ipv4.ip_forward.
This is the code I use. I have no other iptables rules:
iptables -A PREROUTING -t nat -i eth0 -p tcp --dport 443 -j DNAT --to 1.2.3.4:443 iptables -A FORWARD -p tcp -d 1.2.3.4 --dport 443 -j ACCEPT If your default forward policy is DROP then you also need to accept traffic to go back :
iptables -A FORWARD -p tcp -s 1.2.3.4 --sport 443 -j ACCEPT You should secure this a little bit so if your box 1.2.3.4 is compromised at least no forged packet can go through your gateway using source port 443.
IPTABLES=/sbin/iptables [ ... ] $IPTABLES -A PREROUTING -t nat -i eth0 -p tcp --dport 443 -j DNAT --to 1.2.3.4:443 $IPTABLES -I FORWARD -p tcp ! --syn -m state --state NEW -j DROP $IPTABLES -A FORWARD -p tcp -d 1.2.3.4 --dport 443 -m state --state NEW,ESTABLISHED -j ACCEPT $IPTABLES -A FORWARD -p tcp -s 1.2.3.4 --sport 443 -m state --state ESTABLISHED -j ACCEPT 