After upgrading yesterday (VERSION="20200803"), I can no longer ssh into a local machine. I'm assured that the problem is not with the remote machine: not only have I not changed anything on it, but also I can still ssh into it from a third machine as I always have. Here's an attempt from the newly updatetd machine:
$ ssh -vv hostd OpenSSH_8.3p1, OpenSSL 1.1.1g 21 Apr 2020 debug1: Reading configuration data /etc/ssh/ssh_config debug1: /etc/ssh/ssh_config line 20: Applying options for * debug2: resolving "hostd" port 22 debug2: ssh_connect_direct debug1: Connecting to hostd [192.168.0.26] port 22. debug1: Connection established. debug1: identity file /home/zl1/.ssh/id_rsa type 0 debug1: identity file /home/zl1/.ssh/id_rsa-cert type -1 debug1: identity file /home/zl1/.ssh/id_dsa type -1 debug1: identity file /home/zl1/.ssh/id_dsa-cert type -1 debug1: identity file /home/zl1/.ssh/id_ecdsa type -1 debug1: identity file /home/zl1/.ssh/id_ecdsa-cert type -1 debug1: identity file /home/zl1/.ssh/id_ecdsa_sk type -1 debug1: identity file /home/zl1/.ssh/id_ecdsa_sk-cert type -1 debug1: identity file /home/zl1/.ssh/id_ed25519 type -1 debug1: identity file /home/zl1/.ssh/id_ed25519-cert type -1 debug1: identity file /home/zl1/.ssh/id_ed25519_sk type -1 debug1: identity file /home/zl1/.ssh/id_ed25519_sk-cert type -1 debug1: identity file /home/zl1/.ssh/id_xmss type -1 debug1: identity file /home/zl1/.ssh/id_xmss-cert type -1 debug1: Local version string SSH-2.0-OpenSSH_8.3 debug1: Remote protocol version 2.0, remote software version OpenSSH_4.3 debug1: match: OpenSSH_4.3 pat OpenSSH_2*,OpenSSH_3*,OpenSSH_4* compat 0x00000002 debug2: fd 3 setting O_NONBLOCK debug1: Authenticating to hostd:22 as 'zl1' debug1: SSH2_MSG_KEXINIT sent debug1: SSH2_MSG_KEXINIT received debug2: local client KEXINIT proposal debug2: KEX algorithms: curve25519-sha256,curve25519-sha256@libssh.org,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-group14-sha256,ext-info-c debug2: host key algorithms: ecdsa-sha2-nistp256-cert-v01@openssh.com,ecdsa-sha2-nistp384-cert-v01@openssh.com,ecdsa-sha2-nistp521-cert-v01@openssh.com,sk-ecdsa-sha2-nistp256-cert-v01@openssh.com,ssh-ed25519-cert-v01@openssh.com,sk-ssh-ed25519-cert-v01@openssh.com,rsa-sha2-512-cert-v01@openssh.com,rsa-sha2-256-cert-v01@openssh.com,ssh-rsa-cert-v01@openssh.com,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,sk-ecdsa-sha2-nistp256@openssh.com,ssh-ed25519,sk-ssh-ed25519@openssh.com,rsa-sha2-512,rsa-sha2-256,ssh-rsa debug2: ciphers ctos: chacha20-poly1305@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.com debug2: ciphers stoc: chacha20-poly1305@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.com debug2: MACs ctos: umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-64@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1 debug2: MACs stoc: umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-64@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1 debug2: compression ctos: none,zlib@openssh.com,zlib debug2: compression stoc: none,zlib@openssh.com,zlib debug2: languages ctos: debug2: languages stoc: debug2: first_kex_follows 0 debug2: reserved 0 debug2: peer server KEXINIT proposal debug2: KEX algorithms: diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1 debug2: host key algorithms: ssh-rsa,ssh-dss debug2: ciphers ctos: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,rijndael-cbc@lysator.liu.se debug2: ciphers stoc: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,rijndael-cbc@lysator.liu.se debug2: MACs ctos: hmac-md5,hmac-sha1,hmac-ripemd160,hmac-ripemd160@openssh.com,hmac-sha1-96,hmac-md5-96 debug2: MACs stoc: hmac-md5,hmac-sha1,hmac-ripemd160,hmac-ripemd160@openssh.com,hmac-sha1-96,hmac-md5-96 debug2: compression ctos: none,zlib@openssh.com debug2: compression stoc: none,zlib@openssh.com debug2: languages ctos: debug2: languages stoc: debug2: first_kex_follows 0 debug2: reserved 0 debug1: kex: algorithm: (no match) Unable to negotiate with 192.168.1.44 port 22: no matching key exchange method found. Their offer: diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1
Running "zypper up ssh" said "Nothing to do".
I also renamed my ~/.ssh directory on the upgraded machine and replaced it with a copy of the entire ~/.ssh directory from the third (working) machine on my lan. Still no joy. Can anyone tell me what's going on?
ken wrote:
Unable to negotiate with 192.168.1.44 port 22: no matching key exchange method found.
That's it. ^
Your newly upgraded machine no longer allows old diffie-hellman groups.
diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1
Those are the groups supported by the server, but I believe sha1 is considered vulnerable, and your newly upgraded machine refuses to use those.
You could try using ssh -oKexAlgorithms=+diffie-hellman-group-exchange-sha1 user@host
On 8/6/20 12:37 PM, Per Jessen wrote:
ken wrote:
Unable to negotiate with 192.168.1.44 port 22: no matching key exchange method found.
That's it. ^
Your newly upgraded machine no longer allows old diffie-hellman groups.
diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1
Those are the groups supported by the server, but I believe sha1 is considered vulnerable, and your newly upgraded machine refuses to use those.
You could try using ssh -oKexAlgorithms=+diffie-hellman-group-exchange-sha1 user@host
Thanks much, Per. Great answers. And that worked.
But rather than type all that in every time, I think I'll ssh-keygen a new key pair. I liked rsa1 because I could include a comment in the key at the end. Do any of the new ones accommodate a comment?
On 8/6/20 1:16 PM, Andrei Borzenkov wrote:
06.08.2020 20:09, ken пишет:
But rather than type all that in every time,
You can simply add it to ~/.ssh/config
Thanks! That's a good solution for the short term. Later I'll have to upgrade my ssh keys. (Still looking for a non-obsolete key type which permits a comment at the end.
On Thursday, August 6, 2020 12:53 PM, ken gebser@mousecar.com wrote:
On 8/6/20 1:16 PM, Andrei Borzenkov wrote:
06.08.2020 20:09, ken пишет:
But rather than type all that in every time, You can simply add it to ~/.ssh/config
Thanks! That's a good solution for the short term. Later I'll have to upgrade my ssh keys. (Still looking for a non-obsolete key type which permits a comment at the end.
I'm pretty sure that all formats support adding a comment with the "-C" switch. For instance, my ed25519 public keys are in the format
ssh-ed25519 <hash> <comment>
-- Daniel Stevenson
* Daniel Stevenson daniel@dstev.xyz [08-09-20 23:07]:
On Thursday, August 6, 2020 12:53 PM, ken gebser@mousecar.com wrote:
On 8/6/20 1:16 PM, Andrei Borzenkov wrote:
06.08.2020 20:09, ken пишет:
But rather than type all that in every time, You can simply add it to ~/.ssh/config
Thanks! That's a good solution for the short term. Later I'll have to upgrade my ssh keys. (Still looking for a non-obsolete key type which permits a comment at the end.
I'm pretty sure that all formats support adding a comment with the "-C" switch. For instance, my ed25519 public keys are in the format
ssh-ed25519 <hash> <comment>
indeed, ssh-keygen -c [-C comment] [-f keyfile] [-P passphrase]
-
Andrei Borzenkov -
Daniel Stevenson -
ken -
Patrick Shanahan -
Per Jessen