topic Re: HP Secure Shell sftp put issue in Operating System - HP-UX

HP Secure Shell sftp put issue

Jonathan Grymes — Thu, 21 Jul 2011 16:18:19 GMT

I recently upgraded the Hp Secure Shell (T1471AA_A.05.80.002_HP-UX_B.11.23_IA_PA.depot) on an hp rx2620 to:

OpenSSH_5.8p1+sftpfilecontrol-v1.3-hpn13v7, OpenSSL 0.9.8q 2 Dec 2010
HP-UX Secure Shell-A.05.80.002, HP-UX Secure Shell version

We are now seeing problems with several sftp connections where they appear to be hanging when pushing data. We can pull data with no issue. We can log into the remote server but the data put never completes. After a period of time we get the following:

07/21 15:25:41:321569 comms      [015291] SESSION>execpipe: killing child 15296
07/21 15:25:41:322286 comms      [015291] SESSION>execpipe: waiting for 15296
07/21 15:25:41:325841 comms      [015291] SESSION>execpipe: calling old term handler
07/21 15:25:41:325866 comms      [015291] SESSION>TERM signal received: exiting

Any ideas what may be causing they connection to hang on sftp put. We have confirmed no issue on the remote server, no network issue.

Re: HP Secure Shell sftp put issue

Steven E. Protter — Thu, 21 Jul 2011 16:48:06 GMT

Shalom,

Do you receive the same problem with systems not using 05.80 version of Secure Shell?

You may need to swinstall a different version of Secure Shell to get around this problem.

Have you made any changes lately, customizations to the sshd_config file.

SEP

Re: HP Secure Shell sftp put issue

MereSurmiseSir — Tue, 23 Aug 2011 22:45:41 GMT

Did you guys get to the bottom of this? I'm seeing a hang as well with version "OpenSSH_5.8p2, OpenSSL 0.9.7l 28 Sep 2006". The server is custom.

I tracked it down relatively far but my patience is growing thin. Here is what I found:

The sftp process passes off 32K of the plaintext file in a SSH_FXP_WRITE packet to the ssh process in one large writev. The ssh process is breaking up the 32K into 8K chunks, encrypting them, and presumably sending them all out. The problem is that my server is only receiving 3 of these 8K chunks and all indications are that the server really only did send the three. I was thinking maybe there was something in the SSH spec that called for an ACK from the server but my web search on this turned up a ton of hits on sftp put hangs so maybe there is a client-side bug.

Thanks.