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I am setting up NAT on a Linksys WRT54GL for the first time. I'm trying to map a statically-assigned laptop address of 192.168.1.109 to port 40000, and ping it. My end goal is to enable TCP and UDP socket/websocket connections to this machine. It's not working; here are the steps that I've taken. Can anyone spot my error?

  1. On the host laptop:

    • Statically assigned IP address of 192.168.1.109
    • Set up DNS servers and search domains
  2. Under "Applications and Gaming" in the router

    • External Port 40000, Internal Port 40000, protocol UDP, To IP address 192.168.1.109
    • External Port 40001, Internal Port 40001, protocol TCP, To IP address 192.168.1.109

(NOTE: aaa.bbb substituted here because I don't want to post my IP address to the world.)

  • Default gateway in router is aaa.bbb.82.1
  • Router IP address is aaa.bbb.82.134

Results:

  • I am able to ping 192.168.1.109 internally, from another laptop.
  • I am able to ping aaa.bbb.82.1 (about 90m response time)
  • I am NOT able to ping aaa.bbb.82.134
  • I am NOT able to ping aaa.bbb.82.134:40000
  • I am NOT able to ping aaa.bbb.82.134:40001

Where am I going wrong?

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  • are you pinging your public IP from within your LAN? if so, your router must support a feature called Hair-pin NAT, which most consumer grade routers do not implement. In those cases, try a service like checkopenports.utility-application.com . Jun 7, 2017 at 1:32

1 Answer 1

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You will not be able to ping a specific port. This is just not possible. Ping uses the ICMP protocol which, unlike TCP and UDP, doesn't care about ports. You can use telnet to attempt to connect to the port with the following command:

telnet IP port

You can also use nmap to discover any open ports on a host.

Is the Default Gateway your modem? Is this IP address a private address? Does your router have a firewall enabled and is it blocking ICMP requests? We will need more information to better help you along.

If you are going to want to access this from the internet, you will need to give your router a static IP address or use a service such as DynDNS which will map your IP address to a DNS name.

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