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DPC3848V Port Forwarding does not work

Question asked by szepi on Sep 4, 2015
Latest reply on Jun 28, 2016 by tropikalstorm

Hi,

We just got upgraded to use the DPC3848V modem/router. In our previous setup I used port forwarding to forward ports 22 (ssh) and 3690 (svn) as I am running an svn server that my coworkers can access from anywhere in the world. Or they used to be.

It seems that I cannot make the DPC3848V router to do the port forwarding for me.

First, I figured that I had to do a factory reset (hold down the pin in the back of the router for 90 seconds). Once the factory reset was done, I set up port forwarding to forward these ports to the static, internal IP address server that should serve these requests.

However, the only effect his has is that the ports now appear to be "filtered" according to nmap.

 

In particular, without the port forwarding set up, here is the output of nmap:

 

$ nmap -Pn 50.65.XXX.XXX

 

Starting Nmap 6.47 ( http://nmap.org ) at 2015-09-04 21:39 MDT

Nmap scan report for XXXXX.ed.shawcable.net (50.65.XXX.XXX)

Host is up (0.019s latency).

Not shown: 992 closed ports

PORT      STATE    SERVICE

22/tcp    filtered ssh

23/tcp    filtered telnet

53/tcp    open     domain

80/tcp    open     http

443/tcp   open     https

49152/tcp open     unknown

49153/tcp open     unknown

49154/tcp open     unknown

 

With port forwarding set up:

 

 

after pressing save, this is the output:

 

$ nmap -Pn 50.65.XXX.XXX

 

Starting Nmap 6.47 ( http://nmap.org ) at 2015-09-04 21:50 MDT

Nmap scan report for XXXXXXXXX.ed.shawcable.net (50.65.XXX.XXX)

Host is up (0.028s latency).

Not shown: 991 closed ports

PORT      STATE    SERVICE

22/tcp    filtered ssh

23/tcp    filtered telnet

53/tcp    open     domain

80/tcp    open     http

443/tcp   open     https

3690/tcp  filtered svn

49152/tcp open     unknown

49153/tcp open     unknown

49154/tcp open     unknown

 

Nmap done: 1 IP address (1 host up) scanned in 3.13 seconds

 

At least port forwarding changes something, but the weird thing is that the port instead of appearing as open, becomes "filtered".

When I try the service, it times out; and the server does not sense any incoming traffic when I am trying to access it.

When I try the service locally, it works fine.

 

I also tried IP passthrough and DMZ, both without any effect.

 

Any ideas? The previous version of the CISCO router seemed to have other problems (dropping connections), but at least port forwarding was functional.

Am I missing something?

 

Any help would be appreciated.

Bests,

  Csaba

 

Message was edited by Csaba Szepesvari: rescaling screenshot

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