close connect after run ssh command

[zhao-carl]

when i use Run to do something, after thati find a lot of tcp connect and not close.
i see the source code, like this:
func (ssh_conf *MakeConfig) Run(command string) (string, error) {
.....
defer func() {
session.Close()
} ()
...
}

the session is closed, but the tcp connect is not closed.