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We have a MSSQL database configured in a cluster (fail-over). It's working fine for its intended purpose, but we can't seem to monitor availability via OpsView:

check_tcp -H $HOSTADDRESS$ -p 1433

The opsview status for this is Critical:

Connection refused

Is there a way to traceroute to a specific port and rule out rejections from a firewall?

jldugger
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1 Answers1

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telnet is an excellent tool for opening a tcp connection to a random port: telnet localhost 1433, assuming something is on the other end you should get:

Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.

nc (netcat) is also a very handy tool, you can run it on listen mode on one side and connect mode on the other and see if traffic is passing. It will also do udp connections as well.

Stick
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  • Telnet alone isn't very helpful. Telnet: Unable to connect to remote host: Connection refused. Which we already knew. The question is where the refusal is coming from. – jldugger May 29 '09 at 19:19
  • On second thought, it might demonstrate that a connection can be established from localhost. This might be useful, except we already know that connections are working because the webapp is working normally. – jldugger May 29 '09 at 19:20
  • So, you can connect on the local machine, using telnet. But the same connection fails when tried from a remote machine? And you have a firewall setup on your host ? I think you have your answer there – Dave Cheney May 30 '09 at 12:35