Re: Guaranteeing SSH access to specific clients

From	Tauno Voipio <tauno.voipio@notused.fi.invalid>
Newsgroups	comp.os.linux.misc
Subject	Re: Guaranteeing SSH access to specific clients
Date	2022-12-09 17:42 +0200
Organization	A noiseless patient Spider
Message-ID	<tmvl0f$16evk$1@dont-email.me> (permalink)
References	<tmtf02$1ufi$1@gioia.aioe.org> <tmvhru$ccf$1@gioia.aioe.org>

Show all headers | View raw

On 9.12.2022 16.48, Harold Johanssen wrote:
> On Thu, 8 Dec 2022 19:47:14 -0000 (UTC), Harold Johanssen wrote:
> 
>> I don't know whether this is reasonable possible, but I thought I'd ask
>> anyway, just in case:
>>
>> 	Is it possible to guarantee SSH to a specific client, to the
>> exclusion of all other clients? In effect, all other connection would be
>> immediately rejected, even before the SSH protocol exchange gets going.
>> The following requirements must be met:
>>
>> 	- The SSH server must be listening on port 22.
>> 	- The target client may connect from different, arbitrary IP
>> addresses.
>>
>> 	This would be easily possible with tweaked SSH servers and
>> clients, but I am not sure it can be done with off-the-shelf ones.
> 
> 	Thank everybody for your suggestion. Here's what I am going to do:
> 
> 	Since I am talking about a particular Linux SSH server that I
> fully control, and a particular Linux SSH client that I also fully
> control, I am going to make use of the SSH identification string. Since
> this string contemplates an optional field where one can put anything
> (with the constraints mentioned in the relevant RFC) I will use the
> contents of that string to filter out incoming connections.
> 
> 	Initially I will use some arbitrary, fixed string - the changes
> to the SSH client and server codes to support this are trivial. Later on
> I could use a OTP-like scheme, which would not be much more difficult to
> pull off. Either way, my server will reject pests before the SSH protocol
> exchange gets going (which is elaborate and computationally intensive)
> and my client will still work with standard SSH servers. I'll have to
> maintain that code, but that will be a nice entertainment.

There is a such mechanism already in SSH. Google for
'passswordless ssh login'. The generated cryptographic
keys are far more secure than an invented string.

-- 

-TV

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

Thread

Guaranteeing SSH access to specific clients Harold Johanssen <noemail@please.net> - 2022-12-08 19:47 +0000
  Re: Guaranteeing SSH access to specific clients "David W. Hodgins" <dwhodgins@nomail.afraid.org> - 2022-12-08 16:31 -0500
    Re: Guaranteeing SSH access to specific clients Harold Johanssen <noemail@please.net> - 2022-12-09 01:20 +0000
      Re: Guaranteeing SSH access to specific clients "David W. Hodgins" <dwhodgins@nomail.afraid.org> - 2022-12-08 21:43 -0500
      Re: Guaranteeing SSH access to specific clients Robert Heller <heller@deepsoft.com> - 2022-12-09 03:34 +0000
      Re: Guaranteeing SSH access to specific clients stepore <stepore@be.here.now> - 2022-12-08 19:34 -0800
      Re: Guaranteeing SSH access to specific clients "Carlos E.R." <robin_listas@es.invalid> - 2022-12-09 04:42 +0100
        Re: Guaranteeing SSH access to specific clients "26C.Z969" <26C.Z969@noaada.net> - 2022-12-09 01:53 -0500
      Re: Guaranteeing SSH access to specific clients Henning Hucke <h_hucke+spam.news@newsmail.aeon.icebear.org> - 2022-12-09 06:43 +0000
      Re: Guaranteeing SSH access to specific clients The Natural Philosopher <tnp@invalid.invalid> - 2022-12-09 13:29 +0000
      Re: Guaranteeing SSH access to specific clients Allodoxaphobia <trepidation@example.net> - 2022-12-09 13:55 +0000
        Re: Guaranteeing SSH access to specific clients Pancho <Pancho.Jones@proton.me> - 2022-12-09 14:08 +0000
    Re: Guaranteeing SSH access to specific clients Robert Heller <heller@deepsoft.com> - 2022-12-09 03:34 +0000
      Re: Guaranteeing SSH access to specific clients Andreas Kohlbach <ank@spamfence.net> - 2022-12-09 12:44 -0500
        Re: Guaranteeing SSH access to specific clients The Natural Philosopher <tnp@invalid.invalid> - 2022-12-09 17:52 +0000
  Re: Guaranteeing SSH access to specific clients Andreas Kohlbach <ank@spamfence.net> - 2022-12-08 22:31 -0500
  Re: Guaranteeing SSH access to specific clients Richard Kettlewell <invalid@invalid.invalid> - 2022-12-09 12:36 +0000
  Re: Guaranteeing SSH access to specific clients The Natural Philosopher <tnp@invalid.invalid> - 2022-12-09 13:27 +0000
  Re: Guaranteeing SSH access to specific clients Harold Johanssen <noemail@please.net> - 2022-12-09 14:48 +0000
    Re: Guaranteeing SSH access to specific clients Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2022-12-09 17:42 +0200
      Re: Guaranteeing SSH access to specific clients The Natural Philosopher <tnp@invalid.invalid> - 2022-12-09 17:36 +0000
        Re: Guaranteeing SSH access to specific clients Robert Heller <heller@deepsoft.com> - 2022-12-09 19:35 +0000
          Re: Guaranteeing SSH access to specific clients The Natural Philosopher <tnp@invalid.invalid> - 2022-12-10 09:53 +0000
            Re: Guaranteeing SSH access to specific clients Robert Heller <heller@deepsoft.com> - 2022-12-10 13:58 +0000
            Re: Guaranteeing SSH access to specific clients Pancho <Pancho.Jones@proton.me> - 2022-12-10 14:08 +0000
              Re: Guaranteeing SSH access to specific clients Pancho <Pancho.Jones@proton.me> - 2022-12-10 14:15 +0000
            Re: Guaranteeing SSH access to specific clients Andreas Kohlbach <ank@spamfence.net> - 2022-12-10 19:25 -0500
              Re: Guaranteeing SSH access to specific clients Robert Heller <heller@deepsoft.com> - 2022-12-11 00:53 +0000
                Re: Guaranteeing SSH access to specific clients "Carlos E.R." <robin_listas@es.invalid> - 2022-12-11 10:37 +0100
                Re: Guaranteeing SSH access to specific clients Robert Heller <heller@deepsoft.com> - 2022-12-11 12:50 +0000
                Re: Guaranteeing SSH access to specific clients "Carlos E.R." <robin_listas@es.invalid> - 2022-12-11 20:55 +0100
                Re: Guaranteeing SSH access to specific clients Pancho <Pancho.Jones@proton.me> - 2022-12-12 09:35 +0000
                Re: Guaranteeing SSH access to specific clients Richard Kettlewell <invalid@invalid.invalid> - 2022-12-13 08:36 +0000
                Re: Guaranteeing SSH access to specific clients "Carlos E. R." <robin_listas@es.invalid> - 2022-12-15 18:09 +0100
      Re: Guaranteeing SSH access to specific clients Harold Johanssen <noemail@please.net> - 2022-12-09 22:03 +0000
        Re: Guaranteeing SSH access to specific clients The Natural Philosopher <tnp@invalid.invalid> - 2022-12-10 09:56 +0000
          Re: Guaranteeing SSH access to specific clients Ted Heise <theise@panix.com> - 2022-12-16 18:40 +0000

csiph-web