I upgraded from 11.04 to 11.10 and upon completion found that I could no longer ssh into other computers that I routinely do so. There are several things I've checked:
- Kerberos authentication is working fine, that's not the problem.
- I tried restarting and reinstalling ssh, but neither helped.
- I tried copying over all ssh related files from my laptop (with a properly function ssh in 11.04) and replace what is on my 11.10 malfunctioning OS, but that did not help.
I tried deleting the .ssh/known_hosts file. On my next attempt, I received the normal message about connecting somewhere for the first time, but was still refused a connection.
jason:~$ /usr/sbin/sshd -ddd debug2: load_server_config: filename /etc/ssh/sshd_config debug2: load_server_config: done config len = 682 debug2: parse_server_config: config /etc/ssh/sshd_config len 682 debug3: /etc/ssh/sshd_config:5 setting Port 22 debug3: /etc/ssh/sshd_config:9 setting Protocol 2 debug3: /etc/ssh/sshd_config:11 setting HostKey /etc/ssh/ssh_host_rsa_key debug3: /etc/ssh/sshd_config:12 setting HostKey /etc/ssh/ssh_host_dsa_key debug3: /etc/ssh/sshd_config:13 setting HostKey /etc/ssh/ssh_host_ecdsa_key debug3: /etc/ssh/sshd_config:15 setting UsePrivilegeSeparation yes debug3: /etc/ssh/sshd_config:18 setting KeyRegenerationInterval 3600 debug3: /etc/ssh/sshd_config:19 setting ServerKeyBits 768 debug3: /etc/ssh/sshd_config:22 setting SyslogFacility AUTH debug3: /etc/ssh/sshd_config:23 setting LogLevel INFO debug3: /etc/ssh/sshd_config:26 setting LoginGraceTime 120 debug3: /etc/ssh/sshd_config:27 setting PermitRootLogin no debug3: /etc/ssh/sshd_config:28 setting StrictModes yes debug3: /etc/ssh/sshd_config:30 setting RSAAuthentication yes debug3: /etc/ssh/sshd_config:31 setting PubkeyAuthentication yes debug3: /etc/ssh/sshd_config:35 setting IgnoreRhosts yes debug3: /etc/ssh/sshd_config:37 setting RhostsRSAAuthentication no debug3: /etc/ssh/sshd_config:39 setting HostbasedAuthentication no debug3: /etc/ssh/sshd_config:44 setting PermitEmptyPasswords no debug3: /etc/ssh/sshd_config:48 setting ChallengeResponseAuthentication no debug3: /etc/ssh/sshd_config:63 setting X11Forwarding yes debug3: /etc/ssh/sshd_config:64 setting X11DisplayOffset 10 debug3: /etc/ssh/sshd_config:65 setting PrintMotd no debug3: /etc/ssh/sshd_config:66 setting PrintLastLog yes debug3: /etc/ssh/sshd_config:67 setting TCPKeepAlive yes debug3: /etc/ssh/sshd_config:74 setting AcceptEnv LANG LC_* debug3: /etc/ssh/sshd_config:76 setting Subsystem sftp /usr/lib/openssh/sftp-server debug3: /etc/ssh/sshd_config:87 setting UsePAM yes debug1: sshd version OpenSSH_5.8p1 Debian-7ubuntu1 debug3: Incorrect RSA1 identifier debug1: read PEM private key done: type RSA debug1: Checking blacklist file /usr/share/ssh/blacklist.RSA-2048 debug1: Checking blacklist file /etc/ssh/blacklist.RSA-2048 debug1: private host key: #0 type 1 RSA debug3: Incorrect RSA1 identifier debug1: read PEM private key done: type DSA debug1: Checking blacklist file /usr/share/ssh/blacklist.DSA-1024 debug1: Checking blacklist file /etc/ssh/blacklist.DSA-1024 debug1: private host key: #1 type 2 DSA debug3: Incorrect RSA1 identifier debug1: read PEM private key done: type ECDSA debug1: Checking blacklist file /usr/share/ssh/blacklist.ECDSA-256 debug1: Checking blacklist file /etc/ssh/blacklist.ECDSA-256 debug1: private host key: #2 type 3 ECDSA debug1: setgroups() failed: Operation not permitted debug1: rexec_argv='/usr/sbin/sshd' debug1: rexec_argv='-ddd' debug3: oom_adjust_setup Set /proc/self/oom_score_adj from 0 to -1000 debug2: fd 3 setting O_NONBLOCK debug1: Bind to port 22 on 0.0.0.0. Bind to port 22 on 0.0.0.0 failed: Permission denied. debug2: fd 3 setting O_NONBLOCK debug3: sock_set_v6only: set socket 3 IPV6_V6ONLY debug1: Bind to port 22 on ::. Bind to port 22 on :: failed: Permission denied. Cannot bind any address.
Maybe the problem is in that readout, but I'm not familiar enough with this output to know.
My laptop which still has Ubuntu 11.04 still can successfully log into the computers I need to, so the problem is definitely related to the upgrade of my desktop to 11.10.
[edit:] I think I figures something out:
If I do a
ssh -vv email@example.com (the computer I'm trying to log into), towards the end of the output I get:
Jason Nett 11:06:38 PM debug1: Authentications that can continue: gssapi-keyex,gssapi-with-mic,keyboard-interactive debug1: Next authentication method: gssapi-keyex debug1: No valid Key exchange context debug2: we did not send a packet, disable method debug1: Next authentication method: gssapi-with-mic debug2: we sent a gssapi-with-mic packet, wait for reply debug1: Authentication succeeded (gssapi-with-mic). Authenticated to computer.org.com ([xxx.xxx.xxx.xxx]:xx).
Notice: "gssapi-with-mic" is in the list of "Authentications that can continue" and is the one that succeeded. When I try on the machine that lost it's ability to ssh, this output is:
debug1: Authentications that can continue: gssapi-keyex,gssapi-with-mic,keyboard-interactive debug1: Next authentication method: keyboard-interactive debug2: userauth_kbdint debug2: we sent a keyboard-interactive packet, wait for reply debug1: Authentications that can continue: gssapi-keyex,gssapi-with-mic,keyboard-interactive debug2: we did not send a packet, disable method debug1: No more authentication methods to try. Permission denied (gssapi-keyex,gssapi-with-mic,keyboard-interactive).
So on this machine, "gssapi-keyex" and "gssapi-with-mic" are never attempted--according to the verbose output--and only "keyboard-interactive" is attempted. From my online searches, I gather that gssapi-with-mic has something to do with communicating my kerberos authentication, but I'm not quite sure where to go from here, at the moment.
Hopefully this extra info can help us rectify the issue quickly.