The ssh with RHEL 4 is a lot more anal about security checking. In my case, it was the fact that $HOME/.ssh/config was group-writable which was causing it to barf. To fix:
$ cd ~/.ssh $ chmod 600 *
Note that this error message is kind of stupid, since $HOME/.ssh had permissions 700 on it, and $HOME had 750 permissions on it. If any process managed to evade those permissions, changing the permissions on the config file would be similarly defeated.
Bad owner or permissions on .ssh/config
原文：http://www.cnblogs.com/ytjjyy/p/4076442.html