有可能有多个ssh连接到同一个系统吗？

当您第一次设置个人服务器时，您可能会发现自己有很多关于它是什么或不能做什么的问题。有鉴于此，今天的超级用户问答帖子为一位好奇的读者提供了答案。...

有可能有多个ssh连接到同一个系统吗？

当您第一次设置个人服务器时，您可能会发现自己有很多关于它是什么或不能做什么的问题。有鉴于此，今天的超级用户问答帖子为一位好奇的读者提供了答案。

今天的问答环节是由SuperUser提供的，SuperUser是Stack Exchange的一个分支，是一个由社区驱动的问答网站分组。

卡萨布兰卡提供的截图（维基百科共享）。

问题

超级用户读者Sam3000想知道是否可能有多个SSH连接到同一个系统：

I have a Linux computer acting as a server that can accept incoming SSH connecti***. Is it possible to reliably connect multiple devices at the same time, such as my mobile phone and laptop, as well as other desktops, to the same server using SSH?

有可能有多个SSH连接到同一个系统吗？

答案

超级用户badge be和Hastur为我们提供了答案。首先，徽章是：

The Short Answer

Yes, it usually works by default.

The Long Answer

It depends on what you are using it for. It may slow down with multiple connecti***, but that is a bandwidth issue, not an SSH issue.

接着是哈斯特的回答：

Yes it is possible, it is the default behavior. You can rely on it if you are using an updated version of SSH and it is no longer set to Protocol 1. The command below should give you Protocol 2.

grep “Protocol” /etc/ssh/sshd_config

Limits for the Connecti***

You can look upon SSH as an encrypted evolution of telnet, born to allow remote access to a server. Note that SSH connects over TCP and it is able to forward X-sessi*** (graphical sessi***) too. Multi-tasking and multiple users are a part of the inner nature of Unix (even if it is not without limits).

You can see some of those limits in the TCP and SSH limits:

cat /proc/sys/net/core/somaxconn (usually 128, to see the maximum number of TCP outstanding connecti*** you can have)

The kern.ipc.somaxconn sysctl(8) variable limits the size of the listening queue for accepting new TCP connecti***. The default value of 128 is typically too low for robust handling of new connecti*** on a heavily loaded web server.

cat /proc/sys/net/core/netdev_max_backlog (usually 1000, the maximum length of the TCP packet queue)
less /etc/security/limits.conf (you can find the limits for the number of users)
MaxSessi*** in /etc/ssh/sshd_config (specifies the maximum number of open sessi*** permitted per network connection, the default is set at 10)
#MaxStartups 10:30:60, usually commented in the /etc/ssh/sshd_config (specifies the maximum number of concurrent unauthenticated connecti*** to the SSH daemon, the default is set at 10)

References

1. man ssh and man sshd on your computer

2. The man pages for sshd and sshd_config

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