Chrome Version: 53.0.2773.0
Chrome OS Version: 8508.0
Chrome OS Platform: cyan-cheets

Steps To Reproduce:
(1) Start any autotest with test_that by hand from inside the cros_sdk chroot
(2) Once the test has finished, run 'ps auxw |grep ssh' on local and remote

Expected Result:
All ssh connections are closed and have released the associated
 resources
Actual Result:
6 connections have been leaked. There are 6 local ssh processes and on the remote there are 6 sslh-fork and 6sshd processes that are still running

How frequently does this problem reproduce?
Always

What is the impact to the user, and is there a workaround? If so, what is
it?
Running test suites leaks dozens of processes. After a while remote and local machines will have to be rebooted or cleaned by hand, especially for automated tests. Workaround: 'killall ssh' on the local host cleans up everything.