[CentOS] Multiple FreeNX servers and SSH ports

Ned Slider ned at unixmail.co.uk
Sun Mar 21 16:19:55 UTC 2010

Les Mikesell wrote:
> Niki Kovacs wrote:
>> Hi,
>> I've setup a small LAN of two desktops running CentOS 5 in a medical 
>> office. Both are connected to the Internet via a small modem/router.
>> Recently I played around with FreeNX on my own desktop, and I'd like to 
>> install it on these two computers. On my PC, I just redirected port 22 
>> in the router, so SSH (and thus FreeNX) requests from the outside get 
>> redirected to my desktop PC. (And yes, I have a strong password :oD)
>> I'd like to handle the two PCs from the medical office remotely with 
>> FreeNX. I figured that the best way to distinguish them would be to 
>> assign a different port for SSH to each of them, and then redirect each 
>> of the ports respectively.
>> 1) How do I choose different port numbers for SSH ? Any conventions or 
>> caveats for this ?
>> 2) How do I configure these different ports ? By that, I mean : how do I 
>> tell SSH to use them instead of port 22 ?
> You don't really need to change the ports on the hosts.  Just configure the 
> router to accept different ports on the internet side and redirect to port 22 at 
> the different IP addresses on the inside.  Then you only have to change the 
> client settings for access from outside.   I'd move both of them away from port 
> 22 on the outside, though - you'll avoid a lot of password guessing attempts 
> that will happen otherwise.

Not all home/consumer routers will allow redirection to another port - 
some only allow packet forwarding to the *same* port at another IP address.

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