如何创建一个bash脚本来检查SSH连接？ [英] How to create a bash script to check the SSH connection?

问题描述

我在创建一个bash脚本，将登录到远程计算机，并创建私钥和公钥的过程。

I am in the process of creating a bash script that would log into the remote machines and create private and public keys.

我的问题是远程机器不是非常可靠，并且它们并不总是向上。我需要一个bash脚本，如果SSH连接到了那会检查。之前以备将来使用实际创建的键。

My problem is that the remote machines are not very reliable, and they are not always up. I need a bash script that would check if the SSH connection is up. Before actually creating the keys for future use.

推荐答案

您可以用返回值SSH检查，这给你：

You can check this with the return-value ssh gives you:

$ ssh -q user@downhost exit
$ echo $?
255

$ ssh -q user@uphost exit
$ echo $?
0

编辑：另一种方法是使用NMAP（你不需要有键或登录-东西）：

Another approach would be to use nmap (you won't need to have keys or login-stuff):

$ a=`nmap uphost -PN -p ssh | grep open`
$ b=`nmap downhost -PN -p ssh | grep open`

$ echo $a
22/tcp open ssh
$ echo $b
(empty string)

但你必须到grep消息（NMAP不使用返回值显示，如果一个端口过滤，关闭或打开）。

But you'll have to grep the message (nmap does not use the return-value to show if a port was filtered, closed or open).

EDIT2：

如果你有兴趣在ssh端口的实际状态，可以替代的grep打开与 egrep的'开|关|过滤：

If you're interested in the actual state of the ssh-port, you can substitute grep open with egrep 'open|closed|filtered':

$ nmap host -PN -p ssh | egrep 'open|closed|filtered'

只是要完成了。

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