Most organizations do not allow for telnet communications to be enabled by default. One can perform the following tests to ensure that communications over ports:
nc -v <hostname> <port>
For Example, to validate communications on the default agent port of 7520 from your scheduler (AE, DE), you would issue the command string as follows:
From the scheduler server:
nc -v linux-agent 7520
Provided the agent service is up and running on the agent noted above, you should receive a response indicating that we connected. It should look something like this:
[root@linux-ae-server]# nc -v linux-agent 7520
Ncat: Version 6.40 ( http://nmap.org/ncat )
Ncat: Connected to 10.0.0.1:7520.
If you do not receive response similar to the above, then it is likely that either the agent process is down or the communication port is blocked by a firewall. Consult your network administrator as well as your System Administrator (in case a locally installed firewall is running) for assistance in resolving the communication.