Tcp

TCPing

tcping.exe is a small console application that operates similarly to ‘ping’, however it works over a tcp port. License: GPL -¬†Platforms: Win XP, Vista 7 When I have to test if a TCP connection works, like when configuring a NAT or ACL rule, usually I telnet the specific port. TCPing allows to keep the “ping” active on the port to check when the rule works:

Small servers

A quick note about tcp small servers. DOC-CD says: “The TCP small servers consist of three services: Discard (port 9), Echo (port 7), and Chargen (port 19).” If we do a portscan to a router before and after enabling tcp-small-server with the command: R(config)#service tcp-small-servers We can see that these ports are opened: Starting nmap V. 3.00 ( www.insecure.org/nmap/ ) Interesting ports on (10.1.0.254): Port State Service 7/tcp open echo 9/tcp open discard 13/tcp open daytime 19/tcp open chargen The DOC-CD misses port 13 corresponding to¬†Daytime Protocol.