diff --git a/docs/MultiISP.xml b/docs/MultiISP.xml
index 54590b046..9f1a92d5c 100644
--- a/docs/MultiISP.xml
+++ b/docs/MultiISP.xml
@@ -780,6 +780,47 @@ eth1 0.0.0.0/0 130.252.99.27
2 $FW 0.0.0.0/0 tcp 25
+
+ Port Forwarding
+
+ Shorewall provides considerable flexibility for port forwarding in
+ a multi-ISP environment.
+
+ Normal port forwarding rules such as the following will forward
+ from both providers.
+
+ /etc/shorewall/rules:
+
+ #ACTION SOURCE DEST PROTO DEST PORT(S) SOURCE ORIGINAL
+# PORTS(S) DEST
+DNAT net loc:192.168.1.3 tcp 25
+
+ Continuing the above example, to forward only connection requests
+ from ISP 1, you can either:
+
+
+
+ Qualify the SOURCE by ISP 1's interface:
+
+ #ACTION SOURCE DEST PROTO DEST PORT(S) SOURCE ORIGINAL
+# PORTS(S) DEST
+DNAT net:eth0 loc:192.168.1.3 tcp 25
+
+ or
+
+
+
+ Specify the IP address of ISP 1 in the ORIGINAL DEST
+ column:
+
+ #ACTION SOURCE DEST PROTO DEST PORT(S) SOURCE ORIGINAL
+# PORTS(S) DEST
+DNAT net loc:192.168.1.3 tcp 25 - 206.124.146.176
+
+
+
+