trace a particular IP and port

linux networking ubuntu network-programming
murtaza52 picture murtaza52 · Jun 12, 2012 · Viewed 138.1k times · Source

I have an app running on port 9100 on a remote server serving http pages. After I ssh into the server I can curl localhost 9100 and I receive the response.

However I am unable to access the same app from the browser using http://ip:9100

I am also unable to telnet from my local PC. How do I debug it? Is there a way to traceroute a particular IP and port combination, to see where it is being blocked?

Any linux tools / commands / utilities will be appreciated.

Thanks, Murtaza

Answer

EternalHour picture EternalHour · Aug 25, 2015

You can use the default traceroute command for this purpose, then there will be nothing to install.

traceroute -T -p 9100 <IP address/hostname>

The -T argument is required so that the TCP protocol is used instead of UDP.

In the rare case when traceroute isn't available, you can also use ncat.

nc -Czvw 5 <IP address/hostname> 9100

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