Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.os.linux.networking > #4954

Re: Filtering incoming SSH connections

Show all headers | View raw

On 2021-09-07, Clark Smith <noaddress@nowhere.net> wrote:
> 	I would like to be able to filter SSH connections on the basis of 
> specific devices. That is, if the connection comes from a given device D 
> then it is accepted, otherwise it is rejected.
>
> 	The thing is, what property of D can be used for this purpose? 
> Not the IP address when D is a mobile device. Also not the MAC address, 
> for this concept is not contemplated in cellular networks.

I am afraid the IP address is the only information that is available to
your machine to use to decide what to do with. The MAC is available only
if the machine is on the same local network as your machine. 

However, there are a couple of other things you can do. One is to put
ssh onto a different port than the normal one. -- eg port 17224 just to
pick a random number out of the air. The chances of a random attacker
knowing that is verysmall. You can also make it even more difficult
byport knocking. Ie, you set up D so that when it wants to connect, it
sfirst tries on port 1554 and then on port 12443. Neither of those have
sshd listening for a connection but a little script is listening, and
when it gets connection attempts on those two ports it raises a flag for
say 20 sec, and only if the third attempt comes on port 37554 AND the
flag is raised is the connection to ssh allowed. You can cleary make
that as complicated as you want. 

>
> 	What could one possibly use?

Back to comp.os.linux.networking | Previous | Next — Previous in thread | Find similar | Unroll thread

Thread

Filtering incoming SSH connections Clark Smith <noaddress@nowhere.net> - 2021-09-07 23:01 +0000
  Re: Filtering incoming SSH connections Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2021-09-07 23:10 +0000
    Re: Filtering incoming SSH connections Grant Taylor <gtaylor@tnetconsulting.net> - 2021-09-07 19:28 -0600
      Re: Filtering incoming SSH connections Clark Smith <noaddress@nowhere.net> - 2021-09-08 14:41 +0000
        Re: Filtering incoming SSH connections Grant Taylor <gtaylor@tnetconsulting.net> - 2021-09-08 10:32 -0600
          Re: Filtering incoming SSH connections Clark Smith <noaddress@nowhere.net> - 2021-09-08 21:09 +0000
            Re: Filtering incoming SSH connections "Carlos E. R." <robin_listas@es.invalid> - 2021-09-08 23:50 +0200
            Re: Filtering incoming SSH connections Grant Taylor <gtaylor@tnetconsulting.net> - 2021-09-08 23:19 -0600
          Re: Filtering incoming SSH connections William Unruh <unruh@invalid.ca> - 2021-09-09 05:19 +0000
            Re: Filtering incoming SSH connections Grant Taylor <gtaylor@tnetconsulting.net> - 2021-09-09 12:09 -0600
              Re: Filtering incoming SSH connections William Unruh <unruh@invalid.ca> - 2021-09-11 01:16 +0000
              Re: Filtering incoming SSH connections William Unruh <unruh@invalid.ca> - 2021-09-11 01:21 +0000
                Re: Filtering incoming SSH connections Aragorn <thorongil@telenet.be> - 2021-09-11 05:49 +0200
                Re: Filtering incoming SSH connections William Unruh <unruh@invalid.ca> - 2021-09-11 19:26 +0000
                Re: Filtering incoming SSH connections Grant Taylor <gtaylor@tnetconsulting.net> - 2021-09-10 23:55 -0600
                Re: Filtering incoming SSH connections William Unruh <unruh@invalid.ca> - 2021-09-11 19:28 +0000
                Re: Filtering incoming SSH connections Grant Taylor <gtaylor@tnetconsulting.net> - 2021-09-11 15:36 -0600
  Re: Filtering incoming SSH connections Grant Taylor <gtaylor@tnetconsulting.net> - 2021-09-07 19:22 -0600
  Re: Filtering incoming SSH connections Richard Kettlewell <invalid@invalid.invalid> - 2021-09-08 08:49 +0100
  Re: Filtering incoming SSH connections William Unruh <unruh@invalid.ca> - 2021-09-09 05:16 +0000

csiph-web