ZyXEL Port Forwarding

Precis: This guide is intended to help you open an incoming connection to a service you have running locally, for example:

• Operating your own mail server
• Running a gaming server
• Hosting an FTP server
• Getting incoming DCC to work for IRC networks, etc.

This guide is NOT needed to permit outgoing connections to the internet, e.g.:

• surfing Facebook, Twitter, Youtube, etc
• connecting a gaming console to XBox Live
• connecting to streaming media services

Method: there are simply two stages needed: A: permit an incoming connection to a specific port B: set up a Port Forwarding rule to direct the incoming connection to the right destination.

For this example, we are going to open up an incoming connection to port 8080 for a web server running on 10.1.1.1 inside our network.

A: Open A Connection (setting up an ACL - "are we allowed in?")

A firewall rule is needed to permit incoming connections to a named port. Once logged into your router:

1. Navigate to SECURITY > Firewall > Access Control
2. Click Add New ACL Rule
3. Fill in the required information:

The only required fields are:

• Filter Name: the name to give this rule. Make it meaningful so that it's obvious when looking at a later date
• Select Destination Device: the final IP address: 10.1.1.1 in our case
• Custom Destination Port: the port we're opening on the router, 8080 in our case.
• Policy: ACCEPT (else there's no connection, but flicking it to "DROP" later can temporarily close the port)
• Direction: WAN to LAN

Other settings of interest are:

• Order: there may be a rule of higher priority (lower order number here) that may override this rule.
• Source IP Address: it's possible to whitelist specific originating IP ranges (work, known friends, etc). Leaving this blank lets any IP in.
• Select Service: a set of predefined services and port mappings can be specified on the "Protocol" tab then picked from the drop-down here, rather than manually specifying 8080.
• Rate Limit: useful for throttling the amount of bandwidth needed, preventing connections from causing stuttering when streaming media or interrupting VoIP usage, for example.
• Scheduling: useful to specify permitted times (evenings, etc) when free bandwidth is available.

B: Setting a Port Forward rule ("where do we go?")

This is needed to route the incoming port connection through to.

1. Navigate to NETWORK SETTING > NAT > Port Forwarding
2. Click Add New Rule
3. Supply the required information:

The important fields are:

• Active: set to Enable
• Service Name: just a name to reference this by.
• WAN interface: pick your ADSL/VDSL connection
• Ports: it is possible to specify a range here. For a single port, keep both values identical, in our case 8080
• Translated ports: if we're routing through to the same port number, provide the same values here. Specifying different values (e.g.: incoming:8080 -> internal:80) is used for Port Address Translation.
• Server IP Address: oddly, needs to be specified again
• Protocol: safe to leave this at just TCP, but some services also use UDP connections, so set to both initially and change later if required.

That's it! Test it by initiating connections to this port, for example: using "telnet" if necessary.