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Re: Is port 22 safe for SSH through firewall?
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Re: Is port 22 safe for SSH through firewall?



At 12:16 PM -0500 3/14/07, Dave Schroeder wrote:
On Mar 14, 2007, at 12:04 PM, Dan Shoop wrote:

a) SSH scans/probes are very common right now.  Accounts with very bad
passwords may get compromised by these worms.  Moving to a non-standard port
would circumvent this.

Not really. You just disguised the port but any smart attacker will notice the service running on another port and switch to targeting that.

...

No, they won't.* You know that almost all (and probably literally all that this person would encounter in practice) ssh password guessing attacks are against port 22. Now if someone is targeting *that host, specifically*, then yes, they may target ssh on its non-standard port. But nearly, and probably, all scripts and bots out there doing this will try port 22, and upon not finding it there, will assume the machine isn't running ssh. Period. Moving ssh to another port, if someone is so inclined (and no I don't do or recommend this myself; we use other controls) is a perfectly legitimate measure.

- Dave

* Oh, you said *smart* attacker. 99% (and probably actually much higher than 99%) of these attacks aren't smart in any way, shape, or form. Any attack that would notice ssh running on a non-standard port and then specifically attack it would be a targeted attack, and one that most here are never likely to encounter. That's not to say people should use security through obscurity as the ONLY resource; but security through obscurity as an ADDITIONAL resource to other smart and responsible security practices is simply another layer.

When discussing security risks, as I thought we were, and when asking about the risks of running a service, on whatever port, the presumption is generally that we're discussing all the risks, not just those from lame bots. Security and risk assessments need to focus not just on the probable attacks, but the possible attacks.


So while the majority of attacks may be lame ones, easily fooled, I know you're not suggesting that these are the only ones you need to be concerned about.
--


-dhan

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Dan Shoop                                                   AIM: iWiring
Systems & Networks Architect                      http://www.ustsvs.com/
email@hidden                                http://www.iwiring.net/
1-714-363-1174

"The wise man doesn't give the right answers, he poses the right
questions." -- Claude Levi-Strauss

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References: 
 >Re: Is port 22 safe for SSH through firewall? (From: Adam Gerson <email@hidden>)
 >Re: Is port 22 safe for SSH through firewall? (From: Dominic Lepiane <email@hidden>)
 >Re: Is port 22 safe for SSH through firewall? (From: Dan Shoop <email@hidden>)
 >Re: Is port 22 safe for SSH through firewall? (From: Dave Schroeder <email@hidden>)



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