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Testing Firewall connections

 
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Shivkumar
Super Advisor

Testing Firewall connections

Hello,

Most of the WebServers are deployed in DMZ zones.

Sometime we used to test the connections with ping,telnet, and ssh etc.
But sometime they have configured not to respond to any connections
via ping,telnet,and ssh.

I have seen some socket, sock method of testing the connections some places.
Not sure how it works ? Any idea ??

Thanks,
Shiv
4 REPLIES
Tingli
Esteemed Contributor

Re: Testing Firewall connections

I think you can use telnet to do the job.

$ telnet {destination} {port number}

If you can get a login prompt, then it is available. Otherwise, not.
T G Manikandan
Honored Contributor

Re: Testing Firewall connections

Steven Schweda
Honored Contributor
Solution

Re: Testing Firewall connections

> [...] configured not to respond [...]

There is more than one way "not to respond".
For example, normally, a "Connection refused"
complaint (errno = ECONNREFUSED) means that
you reached the destination system, but
there's no one listening (or configured to
respond) at that port.

A fancy firewall could be arranged to respond
in many ways to a connection attempt, so it's
not clear that you can ever really know
what's on the other side.

Much depends on exactly what you mean by
"test the connections". If I wished to test
a Web server, I'd probably ask it to do what
it's intended to do. That is, I'd use a
program like wget to try to fetch a Web page.
It's pretty easy to write a script (for cron
to run periodically) which will try to fetch
a test page, and send an e-mail notification
to someone who might care if it fails. (I do
this on my VMS system, using a
self-resubmitting batch job, but the concept
is essentially similar.)

What, exactly, are you trying to test?
Shivkumar
Super Advisor

Re: Testing Firewall connections

I am trying to test whether firewall connections are in place.