ssh - autossh退出，因为ssh(dropbear)无法解析主机

Question

我在可能具有Internet连接或没有Internet连接的系统上运行autossh。我真的不知道它什么时候有连接，但是如果是这样，我想通过以下方法使autossh建立ssh隧道:

autossh -M 2000 -i /etc/dropbear/id_rsa -R 5022:localhost:22 -R user@host.name -p 6022 -N

几秒钟后，它抛出:

/usr/bin/ssh: Exited: Error resolving 'host.name' port '6022'. Name or service not known

就是这样。 autossh难道不是无论如何都可以保持ssh进程运行吗？我是否真的需要通过ping来检查连接？

Answer 1

您需要将AUTOSSH_GATETIME环境变量设置为0。从autossh(1):

Startup behaviour
 If the ssh session fails with an exit status of 1 on the very first try, autossh

 1.      will assume that there is some problem with syntax or the connection setup,
         and will exit rather than retrying;

 2.      There is a "starting gate" time. If the first ssh process fails within the
         first few seconds of being started, autossh assumes that it never made it
         "out of the starting gate", and exits. This is to handle initial failed
         authentication, connection, etc. This time is 30 seconds by default, and can
         be adjusted (see the AUTOSSH_GATETIME environment variable below). If
         AUTOSSH_GATETIME is set to 0, then both behaviours are disabled: there is no
         "starting gate", and autossh will restart even if ssh fails on the first run
         with an exit status of 1. The "starting gate" time is also set to 0 when the
         -f flag to autossh is used.

 AUTOSSH_GATETIME
         Specifies how long ssh must be up before we consider it a successful connec‐
         tion. The default is 30 seconds. Note that if AUTOSSH_GATETIME is set to 0,
         then not only is the gatetime behaviour turned off, but autossh also ignores
         the first run failure of ssh. This may be useful when running autossh at
         boot.

用法:

AUTOSSH_GATETIME=0 autossh -M 2000 -i /etc/dropbear/id_rsa -R 5022:localhost:22 -R user@host.name -p 6022 -N