Steps to reproduce:
1) grab a windows machine
2) install there minimal git: http://code.google.com/p/msysgit/
3) grab Bamboo 3.4.3 (I think this error will still occur on newer versions too)
4) set up a Plan that uses Git as repository and uses ssh:// protocol, for example:
4.1) url = ssh://git@github.com/atlassian/bamboo-git-plugin.git
(use SSH keyfile as "authentication type" - set up your github account accordingly)
5) use the windows machine from point (1) as a remote agent, connect to bamboo
6) in bamboo administration - set up the remote agent to use Git capability (so it will use native-git checkout instead of jgit checkout)
7) run the plan
8a) observed behavior is that the build hangs at code checkout (possibly to localhost proxy-SSH fingerprint host key checking)
8b) while expected behavior is that the build will... build.

from: BSP-6565
and: https://answers.atlassian.com/questions/39371/ssh-port-on-git-repository-polling