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Full Discussion: SSH hangs
Top Forums UNIX for Advanced & Expert Users SSH hangs Post 302463228 by ccj4467 on Saturday 16th of October 2010 01:33:03 PM
Old 10-16-2010
SSH hangs

Hi all,

At a little bit of loss here. I have a Linux box (Redhat Enterprise 4) that has been working flawlessly for a while, that is until late Tuesday when none of the users could ssh into it. The machine is in a DMZ over which I have no control of the network settings. Here is the debug output from both the client (which is an AIX 5.1 box, although from other types of client machines the results are the same) and the Linux server.

Client debug output:

Code:
/home/cjohnson [25] > ssh -vv xxx.xxx.xxx.xxx

OpenSSH_4.4p1, OpenSSL 0.9.6g 9 Aug 2002
debug1: Reading configuration data /usr/local/etc/ssh_config
debug2: ssh_connect: needpriv 0
debug1: Connecting to 199.46.169.20 [199.46.169.20] port 22.
debug1: Connection established.
debug1: identity file /home/cjohnson/.ssh/identity type 0
debug2: key_type_from_name: unknown key type '-----BEGIN'
debug2: key_type_from_name: unknown key type '-----END'
debug1: identity file /home/cjohnson/.ssh/id_rsa type 1
debug2: key_type_from_name: unknown key type '-----BEGIN'
debug2: key_type_from_name: unknown key type '-----END'
debug1: identity file /home/cjohnson/.ssh/id_dsa type 2
debug1: Remote protocol version 2.0, remote software version OpenSSH_3.9p1
debug1: match: OpenSSH_3.9p1 pat OpenSSH_3.*
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_4.4
debug2: fd 3 setting O_NONBLOCK
debug1: SSH2_MSG_KEXINIT sent

Server debug output:

Code:
Oct 16 12:54:12 localhost sshd[6269]: debug3: fd 4 is not O_NONBLOCK
Oct 16 12:54:12 localhost sshd[6279]: debug1: rexec start in 4 out 4 newsock 4 pipe 7 sock 8
Oct 16 12:54:12 localhost sshd[6269]: debug1: Forked child 6279.
Oct 16 12:54:12 localhost sshd[6269]: debug3: send_rexec_state: entering fd = 8 config len 445
Oct 16 12:54:12 localhost sshd[6269]: debug3: ssh_msg_send: type 0
Oct 16 12:54:12 localhost sshd[6269]: debug3: send_rexec_state: done
Oct 16 12:54:12 localhost sshd[6279]: debug1: inetd sockets after dupping: 3, 3
Oct 16 12:54:12 localhost sshd[6279]: Connection from xxx.xxx.xxx.xxx port 34621
Oct 16 12:54:12 localhost sshd[6279]: debug1: Client protocol version 2.0; client software version OpenSSH_4.4
Oct 16 12:54:12 localhost sshd[6279]: debug1: match: OpenSSH_4.4 pat OpenSSH*
Oct 16 12:54:12 localhost sshd[6279]: debug1: Enabling compatibility mode for protocol 2.0
Oct 16 12:54:12 localhost sshd[6279]: debug1: Local version string SSH-2.0-OpenSSH_3.9p1
Oct 16 12:54:12 localhost sshd[6279]: debug2: fd 3 setting O_NONBLOCK
Oct 16 12:54:12 localhost sshd[6280]: debug3: privsep user:group 74:74
Oct 16 12:54:12 localhost sshd[6279]: debug2: Network child is on pid 6280
Oct 16 16:54:12 localhost sshd[6280]: debug1: permanently_set_uid: 74/74
Oct 16 12:54:12 localhost sshd[6279]: debug3: preauth child monitor started
Oct 16 16:54:12 localhost sshd[6280]: debug1: list_hostkey_types: ssh-rsa,ssh-dss
Oct 16 12:54:12 localhost sshd[6279]: debug3: mm_request_receive entering
Oct 16 16:54:12 localhost sshd[6280]: debug1: SSH2_MSG_KEXINIT sent

My initial guess is that the firewall is allowing the initial connection through on port 22 but then is denying any subsequent connection on non-privileged ports.

Anyone have any ideas?

I know both versions of ssh are old and should be updated but I have just rejoined this project and it is on my todo list.

I should note there have been no changes to the system at all.
 

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sftp-server(1M)                                           System Administration Commands                                           sftp-server(1M)

NAME
sftp-server - SFTP server subsystem SYNOPSIS
/usr/lib/ssh/sftp-server DESCRIPTION
sftp-server implements the server side of the SSH File Transfer Protocol as defined in the IETF draft-ietf-secsh-filexfer. sftp-server is a subsystem for sshd(1M) and must not be run directly. There are no options or config settings. To enable the sftp-server subsystem for sshd add the following to /etc/ssh/sshd_config: Subsystem sftp /usr/lib/ssh/sftp-server See sshd_config(4) for a description of the format and contents of that file. There is no relationship between the protocol used by sftp-server and the FTP protocol (RFC 959) provided by in.ftpd. EXIT STATUS
The following exit values are returned: 0 Successful completion. >0 An error occurred. FILES
/usr/lib/sftp-server ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Availability |SUNWsshdu | +-----------------------------+-----------------------------+ |Interface Stability |Evolving | +-----------------------------+-----------------------------+ SEE ALSO
sftp(1), ssh(1), ssh-add(1), ssh-keygen(1), sshd(1M), sshd_config(4), attributes(5) To view license terms, attribution, and copyright for OpenSSH, the default path is /var/sadm/pkg/SUNWsshdr/install/copyright. If the Solaris operating environment has been installed anywhere other than the default, modify the given path to access the file at the installed location. AUTHOR
Markus Friedl SunOS 5.10 30 Jul 2003 sftp-server(1M)
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