Need a command to check incoming connectivity

ZAMO · 05-25-2015, 02:33 PM

Hi ,

Am looking for a command to check the incoming connectivity on the port 22 and 10022 for a server.
Am able to connect from serverA to serverB on these ports, but is there a way to find out that these ports are allowing incoming connections with any commands(from serverB only), except the iptables?

mralk3 · 05-25-2015, 04:49 PM

What service are you expecting to connect to on each port? You can try connecting with netcat and you can sniff the connection with tcpdump if the two servers are on the same network.

Doug G · 05-25-2015, 10:10 PM

nmap, telnet to the port in question, are a couple more tools you can use.

ZAMO · 05-26-2015, 07:48 AM

Thanks for both the replies .

nmap is not allowed , as like tcpdump . Telnet is not available

Am using

Code:

nc -z -v serverB 22

or

Code:

nc -z -v serverA  10022

from

But nc is not available in serverB . Is there any option that this can be done with netstat?

joec@home · 06-04-2015, 05:00 PM

Quote:

Originally Posted by ZAMO

But nc is not available in serverB . Is there any option that this can be done with netstat?

netstat -l

But you can only do this locally, it will not give you information on the remote server.

linosaurusroot · 06-04-2015, 05:33 PM

You probably have bash. http://thesmithfam.org/blog/2006/05/...with-devtcp-2/

ZAMO · 06-25-2015, 03:44 PM

Code:

You probably have bash. http://thesmithfam.org/blog/2006/05/...with-devtcp-2/

This is a very useful link . But the details in it is not helping me for my requirement .
I can re-describe the requirement here now.

port 22 and 10022 are opened in serverB , so that a user from serverA can reach serverB on these ports . It is a Oneway connection , Reverse connections are not allowed.

Since am sitting in server B , I just want to check the incoming connections are allowed on ServerB from the serverA on the ports 22 and 10022.

Habitual · 06-25-2015, 04:31 PM

Quote:

Originally Posted by ZAMO

Code:

You probably have bash. http://thesmithfam.org/blog/2006/05/...with-devtcp-2/

This is a very useful link . But the details in it is not helping me for my requirement .
I can re-describe the requirement here now.

port 22 and 10022 are opened in serverB , so that a user from serverA can reach serverB on these ports . It is a Oneway connection , Reverse connections are not allowed.

Since am sitting in server B , I just want to check the incoming connections are allowed on ServerB from the serverA on the ports 22 and 10022.

You can check if ServerB ports are open using

Code:

telnet localhost <port>

But you'd be hard pressed to check if ServerA can connect to ServerB's open ports from ServerB.