Rory,

I think you're absolutely correct. I think that some folks here are putting too much weight on looking at assessing risk and vulnerability from a technical control perspective and not on the overall scenario of people performing network sweeps looking for low hanging fruit.
From strictly a technical perspective of sshd running on a different port, there is no risk difference and the vulnerabilities are identical. From the perspective of folks wanting to hide their sshd port from untargeted network sweeps to avoid becoming a target for manual ones, then moving the sshd port can be very effective.

Two different scenarios, two different answers. Of course, publically hanging sshd on a public interface is never a good idea, but necessary sometimes I suppose. If necessary, disable password auth, don't permit root, and I realize that port knocking is kind of old school, but still works as an additional layer in the defense in depth principle.

Ron McKown
CISSP

-----Original Message-----
From: listbounce (at) securityfocus (dot) com [email concealed] [mailto:listbounce (at) securityfocus (dot) com [email concealed]] On Behalf Of Rory Browne
Sent: Friday, June 22, 2012 4:03 AM
To: Mike Hale
Cc: Alex Dolan; Littlefield, Tyler; security-basics (at) securityfocus (dot) com [email concealed]
Subject: Re: server security

Everything I've ever read about security by obscurity, suggests that obscurity no security at all. While I would buy that it isn't a lot of security, I would have difficulty accepting that the only benefit of moving SSH to a different port is less cluttered log files. I would imagine less cluttered log files, mean less attacks, which would translate into less chance of a successful attacks.

While I will accept that the people who say it's no defense at all, probably know a lot more about security than I do, I suspect moving SSH to a different port would render you less susceptible to attacks which scan which collect their list of IPs by scanning for open port 22.

From a defence in depth perspective, I would consider obscurity ( in this case port-moving ), to be quite a thin layer on the onion, but a layer none-the-less. Obscurity through camouflage has been successfully used by various armys ( with the exception of the red-coats ) for centuries, and I find it difficult to understand how it wouldn't apply to computer security.

What am I missing here?

Rory

On 21 June 2012 17:34, Mike Hale <eyeronic.design (at) gmail (dot) com [email concealed]> wrote:
> "Putting it on some other port reduces your risk"
> It doesn't really reduce your risk, since you're still as vulnerable
> as you were before.
>
> What it does is reduce your log entries.  That can be worth the added
> administrative cost of changing standard ports, but it's not really a
> 'security' measure.
>
> On Wed, Jun 20, 2012 at 4:44 PM, Alex Dolan <dolan.alex (at) gmail (dot) com [email concealed]> wrote:
>> One tip I have is to set SSH to a port other than 22, I don't need to
>> tell anyone how devastating it is if someone did actually get access
>> to that service. Putting it on some other port reduces your risk
>>
>> On Thu, Jun 21, 2012 at 1:27 AM, Littlefield, Tyler <tyler (at) tysdomain (dot) com [email concealed]> wrote:
>>> Hello:
>>> I have a couple questions. First, I'll explain what I did:
>>> I set up iptables and removed all unwanted services. Iptables blocks
>>> everything, then only opens what it wants. I also use the addrtype
>>> module to limit broadcast and unspec addresses, etc. I also do some
>>> malformed packet work where I just drop everything that looks
>>> malformed (mainly by the flags).
>>> 2) I secured ssh: blocked root logins, set it up so only users in
>>> the sshusers group can connect, and set it only to allow ppk.
>>> 3) I installed aid.
>>> 4) disabled malformed packets and forwarding/etc in sysctl.
>>> This is a basic web server that runs email, web and a couple other things.
>>> It's only running on a linode512, so I don't have the ability to set
>>> up a ton of stuff; I also think that would make things more of a
>>> mess. What else would be recommended?
>>> Also, I'm looking to add something to the web server; sometimes I
>>> notice that there are a lot of requests from people scanning for
>>> common urls like wordpress/phpbb3/etc, what kind of preventative measures exist for this?
>>>
>>>
>>> --
>>> Take care,
>>> Ty
>>> http://tds-solutions.net
>>> The aspen project: a barebones light-weight mud engine:
>>> http://code.google.com/p/aspenmud
>>> He that will not reason is a bigot; he that cannot reason is a fool;
>>> he that dares not reason is a slave.
>>>
>>>
>>> --------------------------------------------------------------------
>>> ---- Securing Apache Web Server with thawte Digital Certificate In
>>> this guide we examine the importance of Apache-SSL and who needs an
>>> SSL certificate.  We look at how SSL works, how it benefits your
>>> company and how your customers can tell if a site is secure. You
>>> will find out how to test, purchase, install and use a thawte
>>> Digital Certificate on your Apache web server. Throughout, best
>>> practices for set-up are highlighted to help you ensure efficient
>>> ongoing management of your encryption keys and digital certificates.
>>>
>>> http://www.dinclinx.com/Redirect.aspx?36;4175;25;1371;0;5;946;e13b6b
>>> e442f727d1
>>> --------------------------------------------------------------------
>>> ----
>>>
>>
>> ---------------------------------------------------------------------
>> --- Securing Apache Web Server with thawte Digital Certificate In
>> this guide we examine the importance of Apache-SSL and who needs an SSL certificate.  We look at how SSL works, how it benefits your company and how your customers can tell if a site is secure. You will find out how to test, purchase, install and use a thawte Digital Certificate on your Apache web server. Throughout, best practices for set-up are highlighted to help you ensure efficient ongoing management of your encryption keys and digital certificates.
>>
>> http://www.dinclinx.com/Redirect.aspx?36;4175;25;1371;0;5;946;e13b6be
>> 442f727d1
>> ---------------------------------------------------------------------
>> ---
>>
>
>
>
> --
> 09 F9 11 02 9D 74 E3 5B D8 41 56 C5 63 56 88 C0
>
> ----------------------------------------------------------------------
> -- Securing Apache Web Server with thawte Digital Certificate In this
> guide we examine the importance of Apache-SSL and who needs an SSL certificate.  We look at how SSL works, how it benefits your company and how your customers can tell if a site is secure. You will find out how to test, purchase, install and use a thawte Digital Certificate on your Apache web server. Throughout, best practices for set-up are highlighted to help you ensure efficient ongoing management of your encryption keys and digital certificates.
>
> http://www.dinclinx.com/Redirect.aspx?36;4175;25;1371;0;5;946;e13b6be4
> 42f727d1
> ----------------------------------------------------------------------
> --
>

------------------------------------------------------------------------

Securing Apache Web Server with thawte Digital Certificate In this guide we examine the importance of Apache-SSL and who needs an SSL certificate. We look at how SSL works, how it benefits your company and how your customers can tell if a site is secure. You will find out how to test, purchase, install and use a thawte Digital Certificate on your Apache web server. Throughout, best practices for set-up are highlighted to help you ensure efficient ongoing management of your encryption keys and digital certificates.

http://www.dinclinx.com/Redirect.aspx?36;4175;25;1371;0;5;946;e13b6be442
f727d1
------------------------------------------------------------------------

------------------------------------------------------------------------

Securing Apache Web Server with thawte Digital Certificate
In this guide we examine the importance of Apache-SSL and who needs an SSL certificate. We look at how SSL works, how it benefits your company and how your customers can tell if a site is secure. You will find out how to test, purchase, install and use a thawte Digital Certificate on your Apache web server. Throughout, best practices for set-up are highlighted to help you ensure efficient ongoing management of your encryption keys and digital certificates.

http://www.dinclinx.com/Redirect.aspx?36;4175;25;1371;0;5;946;e13b6be442
f727d1
------------------------------------------------------------------------

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