11 ms·

OpenSSH 6.8 released

95 points by mukyu 12y ago

an6n 12y ago
I was hoping for U2F but I guess it's not ready yet. :)
- forgottenpass 12y ago
  Wouldn't that be more in the scope of PAM than an SSHd? Edit: https://github.com/Yubico/pam-u2f https://github.com/Yubico/pam-u2f
- feld 12y ago
  Chrome has access to USB and its own code to handle U2F devices. This would require your SSH client to have the same capabilities. This might work well on Linux/BSD machines, but likely not on OSX due to stagnant unix utility updates and Windows because... well, not a real Unix. Would probably require a heavy wrapper around Putty. Not sure if cygwin and friends would ever work either.
  - aroch 12y ago
    OSX supports PAM auth, U2F is just another kind of PAM. That's how I use my Yubikey.
    - feld 12y ago
      I was thinking that server side it was a PAM module, but client side it was not... for some bizarre reason. So yeah, I suppose if your platform supports PAM this is feasible.
- secure 12y ago
  Track https://bugzilla.mindrot.org/show_bug.cgi?id=2319 https://bugzilla.mindrot.org/show_bug.cgi?id=2319 I worked on this for a while, but lost motivation because of the slow development speed. If you’re more motivated, you’re very welcome to pick up where I left and bring this to thousends of users :).
some_furry 12y ago
The --without-openssl option is particularly attractive on Linux systems if you distrust openssl's code.
- xorcist 12y ago
  It is, but please note that OpenSSH uses very little of OpenSSL's code. None of the serious bugs lately had any impact on OpenSSH.
  - some_furry 12y ago
    That's probably very reassuring. I personally don't share this belief that openssl is bad (in fact, for PHP developers, openssl is preferable to libmcrypt which has been abandoned since 2007), I just know it's a common sentiment of infosec people. :)
    - jamiesonbecker 12y ago
      Just because OpenSSL is very hard to replace doesn't mean it's not very bad.
      - some_furry 12y ago
        Sure. I simply use it for crypto primitives (e.g. aes-256-gcm) in environments where I cannot install libsodium from PECL (e.g. crypto_easybox() and crypto_easybox_open()).
- skrowl 12y ago
  What functionality do you lose if you build it with that option?
  - some_furry 12y ago
    From the article: Disables and removes dependency on OpenSSL. Many features, including SSH protocol 1 are not supported and the set of crypto options is greatly restricted. This will only work on systems with native arc4random or /dev/urandom. I haven't dug into the source code, but I'd wager that the crypto options that remain are Ed25519, ChaCha20-Poly1305, etc. (Don't quote me on this, however.)
beagle3 12y ago
I submitted a very detailed bug report[0] a while ago, which can lead to a DoS (albeit in a very specific setting). I don't expect anyone to rush to fix it, but I'm surprised that there isn't even a comment about it. Is there another place it needs to be reported in? [0] https://bugzilla.mindrot.org/show_bug.cgi?id=2265 https://bugzilla.mindrot.org/show_bug.cgi?id=2265
- LukeShu 12y ago
  Try pointing it out on the mailing list ( openssh-unix-dev@mindrot.org ). Having been on both user and the developer sides, with F/OSS projects, more developers are likely to read every post on the mailing list than every report in the bug tracker.
throwaway7767 12y ago
The host key rotation support sounds very nice, and something I've wanted for a long time: > * ssh(1), sshd(8): Experimental host key rotation support. Add a protocol extension for a server to inform a client of all its available host keys after authentication has completed. The client may record the keys in known_hosts, allowing it to upgrade to better host key algorithms and a server to gracefully rotate its keys. > The client side of this is controlled by a UpdateHostkeys config option (default off). I wish it were on by default, but I guess they want to test it further before enabling it by default. It will remove the temptation to keep using old, weak or suspect keys just because of the hassle of having all the users update their keys or because the admins are afraid of training their users that the scary "HOST KEY HAS CHANGED!!!" warnings are normal and should be ignored.
- jeffcox 12y ago
  I agree, it's an exciting feature with a lot of promise. It does have some potential for abuse, and I think defaulting to off is the proper choice. Even when it's no longer experimental, this is something I imagine you'd want to enable on a per server basis.
- Gracana 12y ago
  But you don't want users to think they're normal and should be ignored. They're an exceptional case and should be understood.
  - throwaway7767 12y ago
    I think you should read the message you are responding to again, as you just agreed with what I said.
deleted 12y ago
[deleted]
w8rbt 12y ago
The sshlog (password logging) patch still seems to work on 6.8 http://w8rbt.org/patches/sshlog.patch
- mortenlarsen 12y ago
  wget is blocked on that URL, any specific reason? wget --user-agent="Not wget" http://w8rbt.org/patches/sshlog.patch http://w8rbt.org/patches/sshlog.patch works.
jamiesonbecker 12y ago
Fingerprint hash tracking is on the plan to add to Userify soon as well, along with host key wipe and regen. Can't wait to get some of these other awesome features mixed in. Of course, we'll have to wait for distributions to catch up.. queue five year wait..
dwb 12y ago
https://bugzilla.mindrot.org/show_bug.cgi?id=1424 https://bugzilla.mindrot.org/show_bug.cgi?id=1424 :( Oh well, refactoring and crypto work is certainly more important. Congrats on the release.
SpaceInvader 12y ago
Finally UseDNS is set to 'no' by default. This is the thing I was ALWAYS changing :)
- Florin_Andrei 12y ago
  I always felt guilty about it, as if I was perhaps missing something obvious. :) Glad to see it gone in the defaults.
hobarrera 12y ago
> [...] SSH protocol version 1.3, 1.5 [...] Do we still need these? Aren't they extremely ancient? Is there any old client that only support these protocol versions and has no security issues, or is out-of-support?
- Sanddancer 12y ago
  I've got a few older Dell switches that still work wonderfully, but only connect via ssh1, not ssh2. They're still useful, and setting up a management vlan isn't that hard, so replacing them is a proposition that's much more expensive than it's worth.
  - hobarrera 12y ago
    That sort of avoids the question: Do those machines still get an up-to-date OpenSSH that's considered trustworthy today? Is there some impediment to upgrade OpenSSH on them?
- marios 12y ago
  "Twitter poll for Unix users: do you still use SSH v.1? If so, how often? Pls. only reply if 'yes' to first question, otherwise RT welcome :)" https://twitter.com/damienmiller/status/570409396913614849 https://twitter.com/damienmiller/status/570409396913614849 Damien Miller is part of the OpenSSH team, so I guess they are considering cleaning that part of the code.
themckman 12y ago
OpenSSH is certainly the standard amongst SSH servers, however, I'm curious if there are serious alternatives that offer something missing in OpenSSH? I know there's a patch floating around that allowed some buffer to be configurable and boosted `scp` performance, for example, but I'm curious if there are other servers that offer anything else interesting.
- ucsdrake 12y ago
  You might find it worth while to investigate mosh[0] as an alternative to OpenSSH. [0] - https://mosh.mit.edu/ https://mosh.mit.edu/
  - philsnow 12y ago
    mosh uses openssh (or some other ssh) under the covers to perform authn + authz and start the remote mosh server (and possibly to communicate the udp port that the remote mosh server is listening on to the client mosh?)
- pwnna 12y ago
  Dropbear is a lightweight replacement for OpenSSH. It runs on things like routers (openwrt) and certain android ROMs.
  - agumonkey 12y ago
    Used it through an sshserver app for Android, had no troubles doing a full scp -R <phone> <backup> with it.
wolf550e 12y ago
I have to configure ssh servers so that putty is able to connect, so I can't follow best practices. Why don't the people working in this area help the putty project with support for the latest stuff?
- clarry 12y ago
  Why don't the people who use and depend on putty help the project with support for the things they need?
  - wolf550e 12y ago
    There aren't a lot of people qualified to work on security software.
- nuclear_eclipse 12y ago
  What best practices would prevent Putty from connecting? Afaik, I'm using most best practices on my own server, and I can connect with Putty just fine.
  - wolf550e 12y ago
    AFAIK, Ed25519 keys and Curve25519 key exchange, AES GCM symmetric encryption.

95 points by mukyu 12y ago

an6n 12y ago

I was hoping for U2F but I guess it's not ready yet. :)

forgottenpass 12y ago
Wouldn't that be more in the scope of PAM than an SSHd? Edit: https://github.com/Yubico/pam-u2f https://github.com/Yubico/pam-u2f
feld 12y ago
Chrome has access to USB and its own code to handle U2F devices. This would require your SSH client to have the same capabilities. This might work well on Linux/BSD machines, but likely not on OSX due to stagnant unix utility updates and Windows because... well, not a real Unix. Would probably require a heavy wrapper around Putty. Not sure if cygwin and friends would ever work either.
- aroch 12y ago
  OSX supports PAM auth, U2F is just another kind of PAM. That's how I use my Yubikey.
  - feld 12y ago
    I was thinking that server side it was a PAM module, but client side it was not... for some bizarre reason. So yeah, I suppose if your platform supports PAM this is feasible.
secure 12y ago
Track https://bugzilla.mindrot.org/show_bug.cgi?id=2319 https://bugzilla.mindrot.org/show_bug.cgi?id=2319 I worked on this for a while, but lost motivation because of the slow development speed. If you’re more motivated, you’re very welcome to pick up where I left and bring this to thousends of users :).

some_furry 12y ago

The --without-openssl option is particularly attractive on Linux systems if you distrust openssl's code.

xorcist 12y ago
It is, but please note that OpenSSH uses very little of OpenSSL's code. None of the serious bugs lately had any impact on OpenSSH.
- some_furry 12y ago
  That's probably very reassuring. I personally don't share this belief that openssl is bad (in fact, for PHP developers, openssl is preferable to libmcrypt which has been abandoned since 2007), I just know it's a common sentiment of infosec people. :)
  - jamiesonbecker 12y ago
    Just because OpenSSL is very hard to replace doesn't mean it's not very bad.
    - some_furry 12y ago
      Sure. I simply use it for crypto primitives (e.g. aes-256-gcm) in environments where I cannot install libsodium from PECL (e.g. crypto_easybox() and crypto_easybox_open()).
skrowl 12y ago
What functionality do you lose if you build it with that option?
- some_furry 12y ago
  From the article: Disables and removes dependency on OpenSSL. Many features, including SSH protocol 1 are not supported and the set of crypto options is greatly restricted. This will only work on systems with native arc4random or /dev/urandom. I haven't dug into the source code, but I'd wager that the crypto options that remain are Ed25519, ChaCha20-Poly1305, etc. (Don't quote me on this, however.)

beagle3 12y ago

I submitted a very detailed bug report[0] a while ago, which can lead to a DoS (albeit in a very specific setting). I don't expect anyone to rush to fix it, but I'm surprised that there isn't even a comment about it. Is there another place it needs to be reported in? [0] https://bugzilla.mindrot.org/show_bug.cgi?id=2265 https://bugzilla.mindrot.org/show_bug.cgi?id=2265

LukeShu 12y ago
Try pointing it out on the mailing list ( openssh-unix-dev@mindrot.org ). Having been on both user and the developer sides, with F/OSS projects, more developers are likely to read every post on the mailing list than every report in the bug tracker.

throwaway7767 12y ago

The host key rotation support sounds very nice, and something I've wanted for a long time: > * ssh(1), sshd(8): Experimental host key rotation support. Add a protocol extension for a server to inform a client of all its available host keys after authentication has completed. The client may record the keys in known_hosts, allowing it to upgrade to better host key algorithms and a server to gracefully rotate its keys. > The client side of this is controlled by a UpdateHostkeys config option (default off). I wish it were on by default, but I guess they want to test it further before enabling it by default. It will remove the temptation to keep using old, weak or suspect keys just because of the hassle of having all the users update their keys or because the admins are afraid of training their users that the scary "HOST KEY HAS CHANGED!!!" warnings are normal and should be ignored.

jeffcox 12y ago
I agree, it's an exciting feature with a lot of promise. It does have some potential for abuse, and I think defaulting to off is the proper choice. Even when it's no longer experimental, this is something I imagine you'd want to enable on a per server basis.
Gracana 12y ago
But you don't want users to think they're normal and should be ignored. They're an exceptional case and should be understood.
- throwaway7767 12y ago
  I think you should read the message you are responding to again, as you just agreed with what I said.

deleted 12y ago

[deleted]

w8rbt 12y ago

The sshlog (password logging) patch still seems to work on 6.8 http://w8rbt.org/patches/sshlog.patch

mortenlarsen 12y ago
wget is blocked on that URL, any specific reason? wget --user-agent="Not wget" http://w8rbt.org/patches/sshlog.patch http://w8rbt.org/patches/sshlog.patch works.

jamiesonbecker 12y ago

Fingerprint hash tracking is on the plan to add to Userify soon as well, along with host key wipe and regen. Can't wait to get some of these other awesome features mixed in. Of course, we'll have to wait for distributions to catch up.. queue five year wait..

dwb 12y ago

https://bugzilla.mindrot.org/show_bug.cgi?id=1424 https://bugzilla.mindrot.org/show_bug.cgi?id=1424 :( Oh well, refactoring and crypto work is certainly more important. Congrats on the release.

SpaceInvader 12y ago

Finally UseDNS is set to 'no' by default. This is the thing I was ALWAYS changing :)

Florin_Andrei 12y ago
I always felt guilty about it, as if I was perhaps missing something obvious. :) Glad to see it gone in the defaults.

hobarrera 12y ago

> [...] SSH protocol version 1.3, 1.5 [...] Do we still need these? Aren't they extremely ancient? Is there any old client that only support these protocol versions and has no security issues, or is out-of-support?

Sanddancer 12y ago
I've got a few older Dell switches that still work wonderfully, but only connect via ssh1, not ssh2. They're still useful, and setting up a management vlan isn't that hard, so replacing them is a proposition that's much more expensive than it's worth.
- hobarrera 12y ago
  That sort of avoids the question: Do those machines still get an up-to-date OpenSSH that's considered trustworthy today? Is there some impediment to upgrade OpenSSH on them?
marios 12y ago
"Twitter poll for Unix users: do you still use SSH v.1? If so, how often? Pls. only reply if 'yes' to first question, otherwise RT welcome :)" https://twitter.com/damienmiller/status/570409396913614849 https://twitter.com/damienmiller/status/570409396913614849 Damien Miller is part of the OpenSSH team, so I guess they are considering cleaning that part of the code.

themckman 12y ago

OpenSSH is certainly the standard amongst SSH servers, however, I'm curious if there are serious alternatives that offer something missing in OpenSSH? I know there's a patch floating around that allowed some buffer to be configurable and boosted `scp` performance, for example, but I'm curious if there are other servers that offer anything else interesting.

ucsdrake 12y ago
You might find it worth while to investigate mosh[0] as an alternative to OpenSSH. [0] - https://mosh.mit.edu/ https://mosh.mit.edu/
- philsnow 12y ago
  mosh uses openssh (or some other ssh) under the covers to perform authn + authz and start the remote mosh server (and possibly to communicate the udp port that the remote mosh server is listening on to the client mosh?)
pwnna 12y ago
Dropbear is a lightweight replacement for OpenSSH. It runs on things like routers (openwrt) and certain android ROMs.
- agumonkey 12y ago
  Used it through an sshserver app for Android, had no troubles doing a full scp -R <phone> <backup> with it.

wolf550e 12y ago

I have to configure ssh servers so that putty is able to connect, so I can't follow best practices. Why don't the people working in this area help the putty project with support for the latest stuff?

clarry 12y ago
Why don't the people who use and depend on putty help the project with support for the things they need?
- wolf550e 12y ago
  There aren't a lot of people qualified to work on security software.
nuclear_eclipse 12y ago
What best practices would prevent Putty from connecting? Afaik, I'm using most best practices on my own server, and I can connect with Putty just fine.
- wolf550e 12y ago
  AFAIK, Ed25519 keys and Curve25519 key exchange, AES GCM symmetric encryption.