reverse ssh

[Erez D]

1. only refer to non-privileged ports
2. btw, ssh will warn you if the server cert changes, so if someone
takes the port for it's ssh server, you will know

i'll still stick with a non standard privileged port.

On Tue, Jul 22, 2014 at 3:47 PM, Guy Gold <guy1gold at gmail.com> wrote:
>
>>>>>
>>>>> On 22 July 2014 00:52, Guy Gold <guy1gold at gmail.com> wrote:
>>>>>>
>>>>>> Hi Erez,
>>>>>>
>>>>>> On Mon, Jul 21, 2014 at 4:18 AM, Erez D <erez0001 at gmail.com> wrote:
>>>>>>>
>>>>>>>
>>>>>>> it is not even a dynamic ip, it is a private ip behind a dynamic one
>>>>>>
>>>>>>
>>>>>> Then,  what Eliyahu wrote should serve you a perfect solution.
>
>
> Although this can become a flame-war :)
>
> Source:
> https://www.adayinthelifeof.nl/2012/03/12/why-putting-ssh-on-another-port-than-22-is-bad-idea/
>
> ==Begin quote ==
>
> But there are more reasons why this is a bad idea and one of the most
> important reason has to do with a bit of the (Linux) way of handling TCP/IP
> ports. When you are logged onto a system as a non-root user (anyone not
> being uid 0), you cannot create a listing TCP or UDP port below 1024. This
> is because port numbers below 1024 are so-called privileged ports and can
> only be opened by root or processes that are running as root. So for
> instance, when your webserver (apache, nginx etc) will start, it will do so
> as the privileged root user in order to open up a listening connection to
> port 80 (the port that by default will be used for HTTP traffic). Now, as
> soon as the port is opened and everything that needs to be done as root is
> done, the webserver will fall back to a non-privileged user (either the
> www-data, apache, or nobody user). From that point, when something bad is
> happening, it is only limited to the rights that that user has.
>
> Now, back to SSH: when we start SSH on port 22, we know for a fact that this
> is done by root or a root-process since no other user could possibly open
> that port. But what happens when we move SSH to port 2222? This port can be
> opened without a privileged account, which means I can write a simple script
> that listens to port 2222 and mimics SSH in order to capture your passwords.
> And this can easily be done with simple tools commonly available on every
> linux system/server. So running SSH on a non-privileged port makes it
> potentially LESS secure, not MORE. You have no way of knowing if you are
> talking to the real SSH server or not. This reason, and this reason alone
> makes it that you should NEVER EVER use a non-privileged port for running
> your SSH server.
>
> ==End quote==
>
> Reading the whole page is recommended.
>
> Though, some of Joshua Thijssen's points can be argued against (not by
> myself, but I'm sure some folks can find some caveats in his article). I
> tend to agree with what he points out.
>
> I do acknowledge that SBO (security by...) divides quite a bit sysadmins
> apart. Some live by it, and some, well, ridicule it, and for them, seeing
> another sysadmin use such method is a tell sign of anachronism.  The beauty
> is that we can all choose, and what is important is  being informed.
>
> --
> Guy Gold
>
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