Differences

This shows you the differences between two versions of the page.

--- linux-packet-forwarding [2017/08/22 08:01] – created baumi
+++ linux-packet-forwarding [2022/01/29 11:27] (current) – [Basic outgoing masquerding script] baumi
@@ Line 1: / Line 1: @@
 ~~META:
 date created = 2017-04-01 09:00
-&date modified = 2017-04-01 09:00
 ~~
 ====== Linux Packet Forwarding ======
+===== Basic outgoing masquerding script =====
 <code bash>
 #!/bin/bash
 network=192.168.3.0/24
 ext_if=eth0
+ext_ip=$(ip address show $ext_if | awk -F "[ /]" '/inet / { print $6 }')
-echo 1 > /proc/net/sys/ipv4/ip_forward
-iptables -t nat -A POSTROUTING -s $network -o $ext_if -J MASQUERADE
+# Turn off forwarding
+echo 0 > /proc/sys/net/ipv4/ip_forward
+# Create NAT rule
+iptables -t nat -I POSTROUTING -s $network -o $ext_if -j SNAT --to-source $ext_ip
+# Create FW rules to allow traffic
+iptables -I FORWARD -s $network -j ACCEPT
+iptables -I FORWARD -m conntrack --ctstate ESTABLISHED -j ACCEPT
+# Turn on forwarding
+echo 1 > /proc/sys/net/ipv4/ip_forward
+</code>
+===== Incoming port forwarding =====
+<code bash>
+#!/bin/bash
+port=80
+host=192.168.3.80
+iptables -t nat -A PREROUTING -m tcp -p tcp --dport $port -j DNAT --to-destination $host:$port
 </code>
 {{tag>kb linux network iptables}}