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emixiak
Posts: 2
Registered: ‎11-20-2008
Accepted Solution

Port forwarding to multiple computers

Hi :smileyhappy: I just bought a wireless Linksys WAG325N router. I usually have about 2-3 machines in my WLAN network and would like to enable port forwarding for each of them on some particular port. It is easy to do so for one exact machine - just type the port number and computer's IP to the configuration - but the problem is - I would like to do it for each of them: for example: enable port XXXX forwarding for 192.168.1.100, 101 and 102. Please help? Thank you in advance.
Expert
Expert
Posts: 12,649
Registered: ‎07-16-2006

Re: Port forwarding to multiple computers

It is not possible. You router has a single public IP address and a single port XXXX on this public IP address and it can thus only forward this single port to a single LAN IP address.
InsightNetworks
Posts: 5
Registered: ‎11-17-2008

Re: Port forwarding to multiple computers

This is application dependant in a sense. You can change the external port allocation to resolve the the correct internal port on each machine.

 

Say for example were using rdp which uses (protocol/port) tcp/3389, the application (RDP client) actually allows you to change the external port to connect to if you specify it after the ip. So for instance say we want to have rdp access to all 3 machines from the outside world. We can setup port forwarding to each computer

 

(Computer)      (internal IP:smileytongue:ort)            (external IP/port)

 Comp A           192.168.0.5:3389            203.x.y.z:3389

Comp B           192.168.0.10:3389           203.x.y.z:3390

Comp C           192.168.0.15:3389           203.x.y.z:3391

 

This is the purpose of a router, to create routing tables.

 

You'll obviously have to remember which ports are allocated to which device.

 

This is certainly application dependant. Find out if your application or service supports the port change, ftp clients, rdp, tftp, ssh all do.. Most 'Good' services do, as those who have constructed it have considered a NAT environment.

 

NAT = Network Address Translation


Most things if not at the application layer, even services in windows are tweakable via the registry. I wouldnt suggest you do this if you dont have the relavent experience. You'll potentially render your workstation inoperable if you get it wrong.

 

Hope this helps.

 

emixiak
Posts: 2
Registered: ‎11-20-2008

Re: Port forwarding to multiple computers

[ Edited ]

Ok I feel you. But another problem emerges - I got only 15 fields to fill up in the configuration. Is it possible to extend it someway?

 

screenshot

 

Message Edited by emixiak on 11-21-2008 01:32 AM
InsightNetworks
Posts: 5
Registered: ‎11-17-2008

Re: Port forwarding to multiple computers

I dont suppose you know if that particular model has Telnet access? If it does you could telnet into the router and issue commands using the CLI (command line interface), unless 15 is all it caters for, but I doubt it. At a guess unless more box's magically appear when you hit that limitation or the router includes telnet you might be out of luck sorry mate. What particular service/application do you want to setup on each machine out of curiosity might well be another way of doing it.
Whizkie
Posts: 1
Registered: ‎12-23-2009

Re: Port forwarding

Hi there all,

 

I  hope one of you can help me....

I have bought a new WRT160NL and I wanted to forward a port so I could use the program Gigatribe.

For some reason my router doesn't remember the data I fill inn?

 

I fill in the fields with; name, port in, port out, both, enable and when press Save Settings, I get the pop-up that the settings are saved, but than a blank screen appears and nothing of the data i filled in is vissible???

Also the port I wanted to forward is still closed.

 

Am I do something wrong here??

 

Kind Regards,

Whizkie

payamazadi
Posts: 1
Registered: ‎12-16-2010

Re: Port forwarding to multiple computers

[ Edited ]

Actually you're pretty wrong. Just because Linksys doesn't offer this doesn't mean it's not possible. The CORRECT functionality, which is (at least) not implemented on WRT320N, is that if you have the same port/port range for an application, you can enable it for multiple computers, and what the router would do is have a list of enabled computers to forward the traffic to. In other words it forwards it to each machine. Sending packets to a destination that isn't listening is a pretty insignificant price to pay to be able to:

- VPN from more than just your office compuer

- Have your kids with different computers be able to host games online

- Bittorrent on multiple computers

 

What's even more pathetic is that the Actiontec routers distributed with verizon fios these days has this feature.

 

(Mod Note: Edited for guideline compliance.)

Expert
Expert
Posts: 12,649
Registered: ‎07-16-2006

Re: Port forwarding to multiple computers

Incorrect. Quote from an Actiontec manual of a MI424WR:

Enter the local IP address or the host name of the computer providing the service in the “Networked Computer/Device” text box. Note that only one local network computer can be assigned to provide a specific service or application.

It's not possible nor makes sense to forward the same port to multiple computers in the LAN. It doesn't make any sense for TCP. And it doesn't make sense for UDP either, in particular if you have "kids with different computers be able to host games online". 2 forwards would double the traffic. 3 forwards would be 3 times the traffic.

Games will usually use UPnP to open the necessary ports choosing available ports.

For VPN or bittorrent of multiple computers you don't need any port forwardings.

If it doesn't work on a router it is often either because of lack of memory of connection tracking (with bittorrents) or some bugs in NAT helper functions to track VPN connections correctly...