[CentOS] Wierd Networking Problem

Bart Schaefer wrote:
> On Oct 31, 2007 12:24 AM, Shawn Everett <shawn at tandac.com> wrote:
>> telnet smtp.isp.net 25 generates the following:
>> Trying a.b.c.d...
>> Connected to smtp.isp.net.
>> Escape character is '^]'.
>>
>> And then nothing.  All other machines can connect to smtp.isp.net 25
>> without a problem.  They also use that host for their outgong mail server.
> 
> Have you contacted "isp.net", whoever they are, to make sure that they
> have not blackholed or tarpitted that particular machine's IP address
> for some reason?

He said that the box is behind a nat and only that box behind the nat 
has a problem. I doubt that it has been specifically targetted by ip.