> systems cannot be fixed (old network hardware, doing V2V conversions from old RHEL, etc)
If you can't update a system, you have no business exposing it to a network. Full stop.
What about isolated networks, a single Ethernet switch for example, used for industrial automation? We can't keep replacing equipment every 5 years because they keep changing crypto protocols.
Many industrial networking protocols have no security at all. No encryption. Not even a password. They achieve their security by being disconnected from the outside world, constrained to a single room or building. If an attacker can get physical access to the wires, then we have a lot more to worry about than network security.
That's the basic discontinuity here. The reason one would want to keep OpenSSH updated and continuing to receive development work is for use in a networked environment without full physical security from the world. If you have something stuck on DSA it shouldn't have any exposure to the world. So there's no problem here. At the very least one could softgap with old-ssh-in-VM that is completely restricted in what it can access.
Ah, another i-know-better tells everyone how to do the things.
Okay, I cut the CAT5 cable with a wire cutter with nonconductive grips (shoulda be safe!), you don't whine what you can't access your mortage/medical history/whatever else thing and should physically be present at the facility to receive the documents.
Deal?
The alternative is these systems never get updated until the next big "welp, the private information of 10 million people just got leaked to the open web". For example, equifax.
Otherwise known as “security”, yes
But sure! If I have a server I currently use OpenSSH to connect then I certainly _could_ airgap the machine and require anyone using it to be in physical proximity to it. But don't you think that might be unrealistic in the vast majority of scenarios?
It seems that the argument for removing support for the old algorithms involves the need to maintain them in the new releases. This only becomes a problem if/when the code and/or regression testing is refactored. So eventually the effort required to remove support becomes less than the effort needed to continually support the old algorithms.
The OpenSSH maintainers can of course do anything they like, but removing support for legacy algorithms is basically passing the problem down to (probably less capable) users who are stuck without the ability to connect to their legacy systems.
Maintaining code also takes time and effort: smaller codebase, effort better spent. If it's too costly to just keep an ancient version of ssh around, and even too costly to pay someone to do that for you, how's it suddenly NOT too costly for the maintainers? If you're going to the lengths of having a special airgapped network of legacy systems, how do you NOT have the tools to use with those systems?
The hypotetical airgapped secure environment, running an old version of SSH (which only supports DSA) has no requirements for a SSH client, just "eh, just bring whichever openssh that you happen to have, and let's assume it works"? That's a failure to plan: if your network is airgapped, you can't expect to have client software in compatible versions appear out of thin ether.
Here's a hypothetical example of a situation closely matching some of my experiences: A long-term support contract exists for some legacy system that cannot be updated because it is under configuration control. The contract involves peripheral development activities, which are best done with the most modern tools available. The whole environment is airgapped, and has security protocols that require security updates to the peripheral development systems, and these are done under a strict and bureaucratic review process. The legacy system interoperates with the development system via a single network connection, which is monitored by a separate entity. (The system is airgapped, but is part of a larger airgapped network, and is protected from unauthorized access even within the airgapped environment.) So you've got a new environment talking to a legacy environment via SSH, and they need to share a common security algorithm. If a new development environment is spun up, and its SSH client does not support the legacy algorithm, then a long and complex delay occurs in which multi-level approvals are required from bureaucrats who are generally not qualified to understand the problem, and are thus inclined to deny approval, to introduce the legacy SSH client software, which will be compared with the modern SSH client for any change history related to security issues, which would include the deletion of these security algorithms. The legacy SSH client would be assumed to be a security risk by the ignorant bureaucrats, and a months-to-years-long process ensues to convince them otherwise.
You're not expecting the toolchain to appear out of thin ether, that was my misunderstanding: you fully expect volunteers to provide you with it for free, for your highly specific situation; in return, you offer...nothing? That's not a very enticing trade.
I sense there may be other ways around this, but those would a) cost you (in a broad sense; after all, the infrastructure is supposedly critical) money, and/or b) cost you (perhaps in a stricter sense) time, effort, perhaps influence. I agree that's rather inconvenient, given the alternative.
It's already insecure, so don't update.
Or you could... not do that... and expect to be hacked, over and over.
Content-free, arrogant, hostile quip that you chose to start.
> Your attitude here is confusingly hostile.
I don't know, perhaps it's you who is projecting and has the problem.
Have a nice day and a happy new year. :]
If you're doing home security, you don't use armed guards and reinforced steel doors, with the defense of depth of an extra-secure bulletproof safe room, because the security would cost more than the value it provides. You might use a good deadbolt though.
The same goes for computer security. In combination with certain security approaches like air gapping, a technically insecure out of band management network can quickly become a dramatically less plausible means of being exploited compared to say - unsexy things like email phishing attacks. So replacing all your servers with ones with supported out of band management systems can simply not be a reasonable priority to have.
Furthermore, no one should place remote access servers on the internet and should instead place them on a private, internal network behind an infrastructure VPN-jumpbox such as OpenVPN or Wireguard.
Only a few extremist developers in control of all of their own software and who don't have to interact with anything in the real world can maintain the idealistic purity to forever run only the latest version of everything.
But the OpenSSH devs are specifically saying “just use the old version if you need this”?
The openssh developers supporting outdated systems and software forever also isn't a long term solution. Why should they pay this cost, but not you (or your company)?
If you can keep unsupported hardware in operation, why can't you keep a containerized openssh image around, or maybe a VM image, or ideally a statically linked executable?
Maybe your company can hire an expert in software archival to set this up and maintain it if needed, or an extra developer to maintain an openssh fork that supports your environment.
Expecting other people (who you don't even pay) to support your outdated systems doesn't really make sense.