how to set up forwarding

Posted on June 22, 2020

i need port forwading i have installed linux debian 9 and vpn server pptp i need forward port 8270 to 192.168.254.2:8270 how to ?

i try with this butnot working

sysctl net.ipv4.ip_forward = 1 iptables -A PREROUTING -t nat -i eth0 -p tcp –dport 8270 -j DNAT –to-destination 192.168.245.1:8270 iptables -A FORWARD -p tcp -d 192.168.245.2 –dport 8270 -j ACEPTA iptables -A POSTROUTING -t nat -s 192.168.245.2 -o eth0 -j MASQUERADE

intente de esta otra manera:

sysctl net.ipv4.ip_forward = 1 iptables -t nat -A PREROUTING -p tcp –dport 8270 -j DNAT –to-destination 192.168.245.2:8270 iptables -t nat -A POSTROUTING -j MASQUERADE

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alexdo

June 30, 2023

Heya,

Just came across this answer and decided to write some general guidelines for anyone who comes across this in the future despite the old question.

To troubleshoot your problem, let’s start with some basic checks:

Ensure that the iptables rules are correctly set up. The destination in the DNAT rule should match the forwarding rule.
Ensure that you have enabled IP forwarding in your sysctl configuration.
Check that there are no firewall rules or security group settings that would block port 8270.

Here’s a corrected example of how you should set your iptables:

sysctl net.ipv4.ip_forward=1
iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 8270 -j DNAT --to-destination 192.168.254.2:8270
iptables -A FORWARD -p tcp -d 192.168.254.2 --dport 8270 -j ACCEPT
iptables -t nat -A POSTROUTING -s 192.168.254.2 -o eth0 -j MASQUERADE

Remember to replace eth0 with the right interfaces in your case.

Also, ensure to make these changes permanent, as they will be lost after a reboot if not saved. You can use iptables-persistent to make the changes permanent.

Here’s a link to the related DigitalOcean documentation

Hope that this helps!