[SSHD-255] sshd does not (always?) reply to requests setting 'want reply'

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.5.0, 0.6.0
• Fix Version/s: 0.10.0

Environment

Seen w/ Gerrit (http://gerrit.googlecode.com) running via Tomcat 7 & Oracle JDK 7 on CentOS 6.x x86_64. Client was TortoiseGit using PuTTY 0.63 for SSH transport. Gerrit 2.5.x uses sshd 0.5.1, Gerrit 2.7.x uses sshd 0.6.0.

• Assignee: Guillaume Nodet
• Reporter: Will Saxon
• Created: 30/Aug/13 21:49
• Updated: 29/Nov/13 19:27
• Resolved: 29/Nov/13 19:26

Description

Upon upgrading to PuTTY 0.63, a developer was unable to fetch changes from Gerrit projects if there were lots of outstanding changes (>200). The fetch would hang.

After consulting w/ the TortoiseGIT and PuTTY developers, it was determined that the hangs occurred as PuTTY was sending several SSH_MSG_CHANNEL_REQUEST 'winadj' messages with the 'want reply' flag set. sshd is not replying to these requests and PuTTY is blocking on the reply, leading to a perceived 'hang' by the user.

I don't have a copy of the entire email exchange, but it reads like the SSH standard indicates replies should only be sent when 'want reply' is true, but sshd always sends replies for requests it understands and never sends replies for requests it does not, regardless of the value of 'want reply'.

Issue Links

• is related to: SSHD-77 Accept SSH-2 names from Putty