Re: Tramp ssh Authentication Problem.

[Ian Barton <lists@wilkesley.net>]

On 08/06/14 09:09, Ian Barton wrote:
> I am having some problems with Tramp logging in to remote servers. In
> my ~/.ssh/config I have:
>
> Host blacky.wilkesley.net
>       IdentityFile ~/.ssh/id_rsa_blacky_linode
> Host wilkesley.org
>      IdentityFile ~/.ssh/id_rsa_linode_ian
>
> I can login to  either host using ssh wilkesley.org or ssh
> blacky.wilkesley.org. However, tramp logs in OK to wilkesley.org, but
> *not* to blacky.wilkesley.net.
>
> If I use the following minimal init file:
>
> (setq tramp-shell-prompt-pattern "^[^$>\n]*[#$%>]*\\(\[[0-9;]*[a-zA-Z]
> *\\)*")
> (eval-after-load 'tramp '(setenv "SHELL" "/bin/bash"))
> (setq tramp-default-method "ssh")
> (setq tramp-verbose 10)
>
> I get the following in the Tramp log when I try to login to
> blacky.wilkesley.net:
>
> 08:52:15.819432 tramp-process-one-action (5) # Looking for regexp
> "\(^.*\([pP]assword\|[pP]assphrase\).*:? *\)\'" from remote shell
> 08:52:15.819650 tramp-get-connection-property (7) # check-remote-echo nil
> 08:52:15.819878 tramp-get-connection-property (7) # check-remote-echo nil
> 08:52:15.820211 tramp-process-one-action (5) # Looking for regexp
> "\(^.*\(Connection \(?:\(?:clo\|refu\)sed\)\|Host key verification
> failed\.\|Login \(?:[Ii]ncorrect\)\|N\(?:ame or service not known\|o
> supported authentication methods left to try!\)\|Permission
> denied\|\(?:Sorry, try again\|Timeout, server not
> responding\)\.\).*\|^.*\(Received signal [0-9]+\).*\)\'" from remote shell
> 08:52:15.820469 tramp-get-connection-property (7) # check-remote-echo nil
> 08:52:15.820697 tramp-get-connection-property (7) # check-remote-echo nil
> 08:52:15.820936 tramp-process-one-action (5) # Looking for regexp
> "\(^[^#$%>
> ]*[#$%>] *\)\'" from remote shell
> 08:52:15.821198 tramp-get-connection-property (7) # check-remote-echo nil
> 08:52:15.821426 tramp-get-connection-property (7) # check-remote-echo nil
> 08:52:15.821635 tramp-process-one-action (5) # Looking for regexp "\(^[^$>
> ]*[#$%>]*\([[0-9;]*[a-zA-Z] *\)*\)\'" from remote shell
> 08:52:15.821866 tramp-get-connection-property (7) # check-remote-echo nil
> 08:52:15.822092 tramp-get-connection-property (7) # check-remote-echo nil
> 08:52:15.822339 tramp-process-one-action (5) # Looking for regexp
> "\(\(Are you sure you want to continue connecting (yes/no)\?\)\s-*\)\'"
> from remote shell
> 08:52:15.822574 tramp-get-connection-property (7) # check-remote-echo nil
> 08:52:15.822799 tramp-get-connection-property (7) # check-remote-echo nil
> 08:52:15.823010 tramp-process-one-action (5) # Looking for regexp
> "\(\(\(?:Store key in cache\? (y/\|Update cached key\? (y/n, Return
> cancels connectio\)n)\)\s-*\)\'" from remote shell
> 08:52:15.823245 tramp-get-connection-property (7) # check-remote-echo nil
> 08:52:15.823502 tramp-get-connection-property (7) # check-remote-echo nil
> 08:52:15.823690 tramp-process-one-action (5) # Looking for regexp
> "\(\(TERM = (.*)\|Terminal type\? \[.*\]\)\s-*\)\'" from remote shell
> 08:52:15.823906 tramp-get-connection-property (7) # check-remote-echo nil
> 08:52:15.824101 tramp-get-connection-property (7) # check-remote-echo nil
> 08:52:15.824277 tramp-process-one-action (5) # Looking for regexp
> "\(\)\'" from remote shell
> 08:52:15.824489 tramp-get-connection-property (7) # check-remote-echo nil
> 08:52:15.838558 tramp-get-connection-property (7) # check-remote-echo nil
> 08:52:15.838773 tramp-process-one-action (5) # Call
> `tramp-action-process-alive'
> 08:52:15.838968 tramp-accept-process-output (10) # *tramp/ssh
> blacky.wilkesley.net* run
> 08:52:16.757812 tramp-accept-process-output (10) #
> #$ Last login: Sun Jun  8 08:51:51 2014 from 46.33.134.31
> 08:52:16.758055 tramp-process-one-action (5) # Looking for regexp
> "\(.*ogin\( .*\)?: *\)\'" from remote shell
> 08:52:16.758317 tramp-get-connection-property (7) # check-remote-echo nil
> 08:52:16.758556 tramp-get-connection-property (7) # check-remote-echo nil
> 08:52:16.758985 tramp-process-one-action (5) # Looking for regexp
> "\(^.*\([pP]assword\|[pP]assphrase\).*:? *\)\'" from remote shell
> 08:52:16.759223 tramp-get-connection-property (7) # check-remote-echo nil
> 08:52:16.759454 tramp-get-connection-property (7) # check-remote-echo nil
> 08:52:16.759688 tramp-process-one-action (5) # Looking for regexp
> "\(^.*\(Connection \(?:\(?:clo\|refu\)sed\)\|Host key verification
> failed\.\|Login \(?:[Ii]ncorrect\)\|N\(?:ame or service not known\|o
> supported authentication methods left to try!\)\|Permission
> denied\|\(?:Sorry, try again\|Timeout, server not
> responding\)\.\).*\|^.*\(Received signal [0-9]+\).*\)\'" from remote shell
>
> For some reason it looks as thought the host key verification is
> failing, but I can't see why.
>
> Ian.
>

A bit more information. Here is the log from the serer when tramp fails 
to login:

Jun 08 12:41:28 blacky.wilkesley.net sshd[19722]: Set 
/proc/self/oom_score_adj to 0
Jun 08 12:41:28 blacky.wilkesley.net sshd[19722]: Connection from 
46.33.134.31 port 51580 on 178.79.179.180 port 22
Jun 08 12:41:29 blacky.wilkesley.net sshd[19722]: reverse mapping 
checking getaddrinfo for dsl-fixed-46-33-134-31.interdsl.co.uk 
[46.33.134.31] failed - POSSIBLE BREAK-IN ATTEMPT!
Jun 08 12:41:29 blacky.wilkesley.net sshd[19722]: Postponed publickey 
for ian from 46.33.134.31 port 51580 ssh2 [preauth]
Jun 08 12:41:29 blacky.wilkesley.net sshd[19722]: Accepted publickey for 
ian from 46.33.134.31 port 51580 ssh2: RSA 
d2:4d:8c:36:40:84:7e:b1:d5:3a:39:37:fe:2f:31:1e
Jun 08 12:41:29 blacky.wilkesley.net sshd[19722]: 
pam_unix(sshd:session): session opened for user ian by (uid=0)

It appears that the public key is accepted OK, but Tramp just hangs. The 
sshd config file is identical on the server that works and the one that 
doesn't.

Ian.