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Beginner

Opening same ports for more then one client.

Hi there,

i am using a service that requires certiain ports to be open for more then one client. untill now I have just had one client that needed the sevice and used

ip nat inside source static tcp 192.168.3.204 53 interface GigabitEthernet0/0 53  for all the ports I needed. This of course doesnt work with more then one cleint. how can i get around this?

Thanks

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Advisor

Re: Opening same ports for more then one client.

You won't be able to do this if you plan on using the same public address. The router will get confused because it won't know which host to send the traffic to. I can think of a couple of ways to get around this though. You could get public addresses to map to whatever you want on whatever ports you need, or you can change the public addressed port meaning that if you have 3 hosts on the lan that need to listen to port 53 and answer on those ports because they can't be changed for whatever reason, you can have a single public address mapped to 1153, 1154, and 1155 for example. Then you could port translations inbound as well as the address:

ip nat inside source static tcp 192.168.3.204 53 interface g0/0 1153

ip nat inside source static tcp 192.168.3.205 53 interface g0/0 1154

ip nat inside source static tcp 192.168.3.206 53 interface g0/0 1155

Obviously for that to work you would need the services on the outside come in on the appropriate port that would map to the correct server. Another way would be to get a dedicated block of addresses.

HTH,
John

*** Please rate all useful posts ***

HTH, John *** Please rate all useful posts ***
4 REPLIES 4
Advisor

Re: Opening same ports for more then one client.

You won't be able to do this if you plan on using the same public address. The router will get confused because it won't know which host to send the traffic to. I can think of a couple of ways to get around this though. You could get public addresses to map to whatever you want on whatever ports you need, or you can change the public addressed port meaning that if you have 3 hosts on the lan that need to listen to port 53 and answer on those ports because they can't be changed for whatever reason, you can have a single public address mapped to 1153, 1154, and 1155 for example. Then you could port translations inbound as well as the address:

ip nat inside source static tcp 192.168.3.204 53 interface g0/0 1153

ip nat inside source static tcp 192.168.3.205 53 interface g0/0 1154

ip nat inside source static tcp 192.168.3.206 53 interface g0/0 1155

Obviously for that to work you would need the services on the outside come in on the appropriate port that would map to the correct server. Another way would be to get a dedicated block of addresses.

HTH,
John

*** Please rate all useful posts ***

HTH, John *** Please rate all useful posts ***
Beginner

Re: Opening same ports for more then one client.

Thanks that worked

Sent from Cisco Technical Support iPad App

Beginner

Re: Opening same ports for more then one client.

If my understanding of the problem is correct, then this can be solved using the rotary option, check this link

http://www.cisco.com/en/US/technologies/tk648/tk361/tk438/technologies_white_paper09186a0080091cb9.html

Sent from Cisco Technical Support iPhone App

Beginner

Re: Opening same ports for more then one client.

I will try this also Thank you.

Sent from Cisco Technical Support iPad App

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