Re: Application level proxy for POP3/SMTP protocol

I am no iptables expert but I know that OpenBSD pf can do this kind of
filtering. Knowing the competition between the two groups, it is most
likely possible. You will just write a redirect with dns enabled on the
ruleset. 

Nick

On Thu, 2006-06-01 at 15:36 +0800, zHihaO wrote:
> Hi all,
> 
> I'm in a sticky situation now because of the filtering of internet 
> traffic out from China. Our users in china have got alot of problems 
> connecting to our servers here to pop their emails and as a result, we 
> have to get a server up in a datacentre in china and setup ssh port 
> forwarding on the server in china. Here is the flow :
> 
> chinese users --> china server (high port. eg: 10000 depending on which 
> local server they are connecting to) --> ssh tunnel --> local server 
> (POP3 port)
> 
> The users in china will connect to our china server like this : 
> china.mail.domain.com:50000. Port 50000 is actually an ssh tunnel to our 
> local servers on port 110 here.
> 
> Problem is we do have a hugh number of servers and it will be hard to 
> keep track of the big number of ssh tunnels/ports opened up from china 
> to our local servers. Any of you know of any good application level 
> proxy that will redirect users based on the result of their dns records? 
> For example, users connecting to the china server running this proxy 
> will be redirected based on the IP address returned when the proxy do a 
> dig on mail.domain.com or mail2.domain.com and redirect them promptly to 
> port 110 of either mail.domain.com or mail2.domain.com depending on the 
> dig result being returned.
> 
> Any help will be greatly appreciated..!!!
> 
> -zhihao