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Old 01-03-2012, 11:44 AM   #1
scampsd
LQ Newbie
 
Registered: Jan 2012
Posts: 3

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Unhappy rsh/ssh problem: POSSIBLE BREAK-IN ATTEMPT, most probably due to DNS configuration


Good afternoon,
On a HP server, I am running Linux Red Hat 5.
I have an application that launches "rsh PSMF" or "ssh PSMF" in background, which goes wrong: the entry "PSMF" is created in the file "/etc/hosts" and the corresponding IP address is found, but there seems to be a mismatch in the other way, as can be seen in following excerpt:

smf1 linus> rsh -v PSMF
OpenSSH_4.3p2, OpenSSL 0.9.8e-fips-rhel5 01 Jul 2008
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Applying options for *
debug1: Applying options for *
debug1: Connecting to PSMF [xxx.xxx.xxx.xxx] port 22.
debug1: Connection established.
debug1: identity file /osp/local/home/linus/.ssh/id_rsa type 1
debug1: identity file /osp/local/home/linus/.ssh/id_dsa type -1
debug1: loaded 2 keys
debug1: Remote protocol version 2.0, remote software version OpenSSH_4.3
debug1: match: OpenSSH_4.3 pat OpenSSH*
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_4.3
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: server->client aes128-ctr hmac-md5 none
debug1: kex: client->server aes128-ctr hmac-md5 none
debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<1024<8192) sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP
debug1: SSH2_MSG_KEX_DH_GEX_INIT sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY
debug1: Host 'psmf' is known and matches the RSA host key.
debug1: Found key in /osp/local/home/linus/.ssh/known_hosts:1
debug1: ssh_rsa_verify: signature correct
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug1: SSH2_MSG_SERVICE_REQUEST sent
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey,gssapi-with-mic,password
debug1: Next authentication method: gssapi-with-mic
Address xxx.xxx.xxx.xxx maps to smf1, but this does not map back to the address - POSSIBLE BREAK-IN ATTEMPT!
debug1: Unspecified GSS failure. Minor code may provide more information
Unknown code krb5 195

debug1: Unspecified GSS failure. Minor code may provide more information
Unknown code krb5 195

debug1: Unspecified GSS failure. Minor code may provide more information
Unknown code krb5 195

debug1: Next authentication method: publickey
debug1: Offering public key: /osp/local/home/linus/.ssh/id_rsa
debug1: Server accepts key: pkalg ssh-rsa blen 277
debug1: read PEM private key done: type RSA
debug1: Authentication succeeded (publickey).
debug1: channel 0: new [client-session]
debug1: Entering interactive session.
debug1: Sending environment.
debug1: Sending env LANG = C
Last login: Tue Jan 3 17:31:27 2012 from xxx.xxx.xxx.xxx

[1] 2916
End of linus profile


I have been looking on the internet and it seems that a wrong DNS configuration might be causing this issue. Unfortunately I don't know how to verify my DNS configuration and even then, I don't know how to interpret the "rsh -v" output.

(As there seems to be a security issue, I have blanked out the IP address (xxx.xxx.xxx.xxx), but I confirm that it is correct.)

Can somebody help me?
Thanks
Dominique
 
Old 01-03-2012, 12:46 PM   #2
unSpawn
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Quote:
Originally Posted by scampsd View Post
Code:
debug1: Authentications that can continue: publickey,gssapi-with-mic,password
debug1: Next authentication method: gssapi-with-mic
Address xxx.xxx.xxx.xxx maps to smf1, but this does not map back to the address - POSSIBLE BREAK-IN ATTEMPT!
debug1: Unspecified GSS failure.  Minor code may provide more information
Unknown code krb5 195
If 'ssh -o GSSAPIAuthentication no PSMF' doesn't produce those lines try disabling anything GSSAPI in your configuration?
 
Old 01-04-2012, 05:05 AM   #3
scampsd
LQ Newbie
 
Registered: Jan 2012
Posts: 3

Original Poster
Rep: Reputation: Disabled
Thanks for the fast reply.
I have launched the mentioned command and I get the following:
ssh -o GSSAPIAuthentication no PSMF
command-line line 0: Missing yes/no argument.


When you write about disabling GSSAPI, how can I do this (I know, I'm a newbie)?
Thanks
Dominique
 
Old 01-04-2012, 08:24 AM   #4
unSpawn
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Quote:
Originally Posted by scampsd View Post
Code:
ssh -o GSSAPIAuthentication no PSMF
command-line line 0: Missing yes/no argument.
Sorry, should be 'ssh -o GSSAPIAuthentication=no PSMF'.


Quote:
Originally Posted by scampsd View Post
When you write about disabling GSSAPI, how can I do this
If you have one, your personal ~/.ssh/config may list defaults for all connections. To tweak just one connection add a section (below what's there already):
Code:
Host PSMF
GSSAPIAuthentication no
That's all.
 
1 members found this post helpful.
Old 01-04-2012, 09:12 AM   #5
scampsd
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Registered: Jan 2012
Posts: 3

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Thumbs up

Thanks a lot, you have saved my day!
 
Old 01-04-2012, 09:35 AM   #6
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You're welcome, please mark the thread solved.
 
  


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