Hi guys, I'm a little disapointed ! My aim was to build a VERY simple smtp proxy under debian to handle mail from a port (51234) and forward it to the standard 25 port. I compile and install a "delegate" witch can handle easily that. It's working very well like that : delegated SERVER="smtp://anotherSmtpServer:25" -P51234 The strange thing is, it's working on my virtual test machine and on the dedicated server in local but I can't manage to use it trought internet. I test it like that. telnet [mySrv] 51234 Of course, no firewal, no deny host, no ined/xined, the service delegated is listening on the right port ... 2 clues : The port is answering trought internet with nmap as "51234/tcp open tcpwrapped" have a look at the tcpdump following : 22:50:54.864398 IP [myIp].1699 [mySrv].51234: S 2486749330:2486749330(0) win 65535 22:50:54.864449 IP [mySrv].51234 [myIp].1699: S 2486963525:2486963525(0) ack 2486749331 win 5840 22:50:54.948169 IP [myIp].1699 [mySrv].51234: . ack 1 win 64240 22:50:54.965134 IP [mySrv].43554 [myIp].auth: S 2485396968:2485396968(0) win 5840 22:50:55.243128 IP [myIp] [mySrv]: ICMP [myIp] tcp port auth unreachable, length 68 22:50:55.249646 IP [mySrv].51234 [myIp].1699: F 1:1(0) ack 1 win 46 22:50:55.309853 IP [myIp].1699 [mySrv].51234: . ack 2 win 64240 22:50:55.310126 IP [myIp].1699 [mySrv].51234: F 1:1(0) ack 2 win 64240 22:50:55.310137 IP [mySrv].51234 [myIp].1699: . ack 2 win 46 The part "auth" seems suspect to me but didn't ring a bell. I could certaily do with some help. Thx a lot !