I am facing a problem in a foreign country reaching a special server per TCP/IP. ICMP is no problem but it looks like the dialup access provider is somehow filtering the TCP port 25 (SMTP). I get a connection refused when trying this port. However in the same moment I get an ICMP message from a nearby host:
22 3.250098363 126.96.36.199 192.168.1.24 ICMP 94 Destination unreachable (Communication administratively filtered)[Packet size limited during capture]
As far as I can see the access provider is Orange in France.
I assume it is a type of filtering mechanism by the access provider. But why is this, what might be the reason and is it well known practice at all?
PS: Port 25 is not filtered by default. I can not reach a specific server only.