4 ms·

So basically, the recommended solution is “instead of us maintaining DSA support, everybody should maintain their own fork of an old OpenSSH version”?

extinctpotato 3y ago
Yes.
caboteria 3y ago
https://xkcd.com/1172/ https://xkcd.com/1172/
morelisp 3y ago
Not "everybody", just "not us".
mynameisvlad 3y ago
DSA support isn’t free. It requires maintenance. We aren’t entitled to lifetime support.
- pkaye 3y ago
  Is there active work being done on the DSA code recently?
  - timv 3y ago
    The main source code for DSA is here https://cvsweb.openbsd.org/cgi-bin/cvsweb/src/usr.bin/ssh/ssh-dss.c https://cvsweb.openbsd.org/cgi-bin/cvsweb/src/usr.bin/ssh/ss... You can see that the team did a big refactor of key handling about 14 months ago that required multiple rounds changes to the DSA code. That's the sort of cost that legacy code brings - it's not about make changing to the DSA feature, it's about the cost of maintaining the DSA code when you make changes across the codebase. In the original mail, DJM mentions that they'd like to explore a post-quantum signature algorithm. Adding that to the codebase is likely to require some broad changes to key management, and that will be less work if there are fewer supported key types.
crote 3y ago
Nah, it simply won't be maintained by anyone - just like the gear still requiring DSA. Nobody is going to stop you from using the last DSA-included OpenSSH build for the next few decades, just don't expect any updates.
quickthrowman 3y ago
Probably not since replacing the ancient equipment only capable of DSA is likely cheaper than maintaining an OpenSSH fork. I’m going to assume that the hardware that supports DSA only has long been abandoned by its manufacturer.
- womod 3y ago
  You'd be suprised, the shear amount of black box vendor nonsense out there borders on astronomical. Weird telco stuff, old cisco hardware, BMCs in servers, it would mean gutting probably millions of dollars of equiment. It's stupid, but throwing the baby out with the bathwater over openssh won't make anyone happy.
  - quickthrowman 3y ago
    Some day that stuff is going to unexpectedly break and cause more problems. There are two choices; pain now when you have a chance to plan, or more pain later when you’re forced to react.
Macha 3y ago
So the people providing software for free should support things indefinitely because the people you've paid money for those things won't?
- Sesse__ 3y ago
  Well, they are seemingly explicitly calling out Debian as your new favorite place for SSHv1 support :-) Who are no more paid than they are.
  - lilyball 3y ago
    I imagine the "people you've paid money" refers to the vendors of the old hardware that requires DSA.
- lnxg33k1 3y ago
  Oh this is beautiful and perfect, couldn’t have said it better, people are so awesome in their entitlement
nayuki 3y ago
I mean that's the deal you enter into with open-source software. In exchange for having full access to the source code for free, you should have no expectations of entitlement of new features or continued support from upstream.
halJordan 3y ago
If you have no problem using an obviated algorithm why is there suddenly a problem using an obviated ssh? These complaints almost beggar belief.
- deleted 3y ago
  [deleted]
- Jenda_ 3y ago
  Because the old algorithm only endangers the communication and the remote device (and this may even not be the case, as such an old device should not be exposed to the world), while the old client may compromise security of the local computer. (fortunately, bugs in SSH client are uncommon; with e.g. browsers it's a different story) Of course a reasonable solutions would be to run it in some sandbox/VM. Additionally, the old client will be difficult to use in a current OS because of library and general system incompatibility (Debian with openssh-client-ssh1 is a rare exception, and it's just a command-line ssh, not the library mentioned in https://news.ycombinator.com/item?id=38963372 https://news.ycombinator.com/item?id=38963372).
kelnos 3y ago
More or less, yes. You get OpenSSH for free; you are not paying for it, and not paying to support its development. Critically, you are not paying for its developers to support old, obsolete, broken cryptography. Keeping DSA would be an added maintenance burden that the OpenSSH team just isn't prepared to continue taking on. If there's a wide need for it, hopefully everybody won't maintain their own fork; all that's necessary is people band together and maintain a single fork.
Panino 3y ago
I started using OpenSSH in OpenBSD 2.6, released in 1999, and I don't believe I've ever even used a DSA key. Here's a quote from the release notes of OpenSSH 1.2.3, released March 6, 2000: "Any user can create any number of user authentication RSA keys for his/her own use. Each user has a file which lists the RSA public keys for which proof of possession of the corresponding private key is accepted as authentication. User authentication keys are typically 1024 bits." ECDSA key authentication was added in OpenSSH 5.7, released in January 2011: https://www.openssh.com/txt/release-5.7 https://www.openssh.com/txt/release-5.7 Ed25519 key authentication was added in OpenSSH 6.5, released in January 2014: https://www.openssh.com/txt/release-6.5 https://www.openssh.com/txt/release-6.5 And RSA support has been around since the beginning. I think the overlap between "must use DSA keys" and "uses modern OpenSSH" is practically zero, and the level of pushback in this thread doesn't correspond to reality.
127361 3y ago
Or just not upgrading the entire operating system, say for example in an industrial control system. Because we find that this old version of SSH no longer compiles on modern operating systems. Thus making the whole system more vulnerable, so that it can keep communicating with some 10-year old device that cannot be easily replaced. Again, air-gapping and limiting the physical extent of the network to the room or building would provide significant protection against attacks here.
chasil 3y ago
You could alternately install alternate SSH clients (non-OpenSSH) for this purpose. $ rpm -qi putty | tail -1 Putty is a SSH, Telnet & Rlogin client - this time for Linux. $ rpm -qi dropbear | tail -2 Dropbear is a relatively small SSH server and client. It's particularly useful for "embedded"-type Linux (or other Unix) systems, such as wireless routers. The focus for SSH is safety. These others shift more to broad compatibility; I do wish they would throw warnings for weak ciphers.
throw0101d 3y ago
> […] “instead of us maintaining DSA support, everybody should maintain their own fork of an old OpenSSH version”? "Instead of of us maintaining DSA for a smaller and smaller population, that small/shrinking population should take some responsibility on themselves."

extinctpotato 3y ago

Yes.

caboteria 3y ago

https://xkcd.com/1172/ https://xkcd.com/1172/

morelisp 3y ago

Not "everybody", just "not us".

mynameisvlad 3y ago

DSA support isn’t free. It requires maintenance. We aren’t entitled to lifetime support.

pkaye 3y ago
Is there active work being done on the DSA code recently?
- timv 3y ago
  The main source code for DSA is here https://cvsweb.openbsd.org/cgi-bin/cvsweb/src/usr.bin/ssh/ssh-dss.c https://cvsweb.openbsd.org/cgi-bin/cvsweb/src/usr.bin/ssh/ss... You can see that the team did a big refactor of key handling about 14 months ago that required multiple rounds changes to the DSA code. That's the sort of cost that legacy code brings - it's not about make changing to the DSA feature, it's about the cost of maintaining the DSA code when you make changes across the codebase. In the original mail, DJM mentions that they'd like to explore a post-quantum signature algorithm. Adding that to the codebase is likely to require some broad changes to key management, and that will be less work if there are fewer supported key types.

crote 3y ago

Nah, it simply won't be maintained by anyone - just like the gear still requiring DSA. Nobody is going to stop you from using the last DSA-included OpenSSH build for the next few decades, just don't expect any updates.

quickthrowman 3y ago

Probably not since replacing the ancient equipment only capable of DSA is likely cheaper than maintaining an OpenSSH fork. I’m going to assume that the hardware that supports DSA only has long been abandoned by its manufacturer.

womod 3y ago
You'd be suprised, the shear amount of black box vendor nonsense out there borders on astronomical. Weird telco stuff, old cisco hardware, BMCs in servers, it would mean gutting probably millions of dollars of equiment. It's stupid, but throwing the baby out with the bathwater over openssh won't make anyone happy.
- quickthrowman 3y ago
  Some day that stuff is going to unexpectedly break and cause more problems. There are two choices; pain now when you have a chance to plan, or more pain later when you’re forced to react.

Macha 3y ago

So the people providing software for free should support things indefinitely because the people you've paid money for those things won't?

Sesse__ 3y ago
Well, they are seemingly explicitly calling out Debian as your new favorite place for SSHv1 support :-) Who are no more paid than they are.
- lilyball 3y ago
  I imagine the "people you've paid money" refers to the vendors of the old hardware that requires DSA.
lnxg33k1 3y ago
Oh this is beautiful and perfect, couldn’t have said it better, people are so awesome in their entitlement

nayuki 3y ago

I mean that's the deal you enter into with open-source software. In exchange for having full access to the source code for free, you should have no expectations of entitlement of new features or continued support from upstream.

halJordan 3y ago

If you have no problem using an obviated algorithm why is there suddenly a problem using an obviated ssh? These complaints almost beggar belief.

deleted 3y ago
[deleted]
Jenda_ 3y ago
Because the old algorithm only endangers the communication and the remote device (and this may even not be the case, as such an old device should not be exposed to the world), while the old client may compromise security of the local computer. (fortunately, bugs in SSH client are uncommon; with e.g. browsers it's a different story) Of course a reasonable solutions would be to run it in some sandbox/VM. Additionally, the old client will be difficult to use in a current OS because of library and general system incompatibility (Debian with openssh-client-ssh1 is a rare exception, and it's just a command-line ssh, not the library mentioned in https://news.ycombinator.com/item?id=38963372 https://news.ycombinator.com/item?id=38963372).

kelnos 3y ago

More or less, yes. You get OpenSSH for free; you are not paying for it, and not paying to support its development. Critically, you are not paying for its developers to support old, obsolete, broken cryptography. Keeping DSA would be an added maintenance burden that the OpenSSH team just isn't prepared to continue taking on. If there's a wide need for it, hopefully everybody won't maintain their own fork; all that's necessary is people band together and maintain a single fork.

Panino 3y ago

I started using OpenSSH in OpenBSD 2.6, released in 1999, and I don't believe I've ever even used a DSA key. Here's a quote from the release notes of OpenSSH 1.2.3, released March 6, 2000: "Any user can create any number of user authentication RSA keys for his/her own use. Each user has a file which lists the RSA public keys for which proof of possession of the corresponding private key is accepted as authentication. User authentication keys are typically 1024 bits." ECDSA key authentication was added in OpenSSH 5.7, released in January 2011: https://www.openssh.com/txt/release-5.7 https://www.openssh.com/txt/release-5.7 Ed25519 key authentication was added in OpenSSH 6.5, released in January 2014: https://www.openssh.com/txt/release-6.5 https://www.openssh.com/txt/release-6.5 And RSA support has been around since the beginning. I think the overlap between "must use DSA keys" and "uses modern OpenSSH" is practically zero, and the level of pushback in this thread doesn't correspond to reality.

127361 3y ago

Or just not upgrading the entire operating system, say for example in an industrial control system. Because we find that this old version of SSH no longer compiles on modern operating systems. Thus making the whole system more vulnerable, so that it can keep communicating with some 10-year old device that cannot be easily replaced. Again, air-gapping and limiting the physical extent of the network to the room or building would provide significant protection against attacks here.

chasil 3y ago

You could alternately install alternate SSH clients (non-OpenSSH) for this purpose. $ rpm -qi putty | tail -1 Putty is a SSH, Telnet & Rlogin client - this time for Linux. $ rpm -qi dropbear | tail -2 Dropbear is a relatively small SSH server and client. It's particularly useful for "embedded"-type Linux (or other Unix) systems, such as wireless routers. The focus for SSH is safety. These others shift more to broad compatibility; I do wish they would throw warnings for weak ciphers.

throw0101d 3y ago

> […] “instead of us maintaining DSA support, everybody should maintain their own fork of an old OpenSSH version”? "Instead of of us maintaining DSA for a smaller and smaller population, that small/shrinking population should take some responsibility on themselves."