how to find out if a port is available on a remote machine?

UNIX for Advanced & Expert Users
1

hi,

I can ping into another unix machine, but I cannot seem to access a certain application. I think it might be because I am now allowed to connect to the port (because of firewall configuration).

How can I find out if I have access to a port on another machine?

thanks

2

A simple first step is to attempt to telnet to the specific port

telnet <server> <port>
3

using telnet, try connecting to that port: telnet ip_address port_num
if the port is open, you'll see something like:

yogeshs@yogesh-laptop:/tmp$ telnet 10.2.28.51 22
Trying 10.2.28.51...
Connected to 10.2.28.51.
Escape character is '^]'.
SSH-1.99-OpenSSH_3.9p1

now press ctrl+] and hit enter. when you get telnet> prompt, type quit and press enter.

if the port is closed, you'll see something like:

yogeshs@yogesh-laptop:/tmp$ telnet 10.2.28.51 222
Trying 10.2.28.51...
telnet: Unable to connect to remote host: Connection refused
yogeshs@yogesh-laptop:/tmp$