# open_ex: ['ssh','-O','check','-T','-S','/root/.libnet-openssh-perl/user-10.253.10.10-25316-608967','-l','user','10.253.10.10','--']
# _waitpid(25319) => pid: 25319, rc: 0, err:
# open_ex: ['ssh','-S','/root/.libnet-openssh-perl/user-10.253.10.10-25316-608967','-l','user','10.253.10.10','--','show clock']
# _waitpid(25320) => pid: 25320, rc: 0, err:
# open_ex: ['ssh','-O','exit','-T','-S','/root/.libnet-openssh-perl/user-10.253.10.10-25316-608967','-l','user','10.253.10.10','--']
# _waitpid(25321) => pid: 25321, rc: 0, err: