ssh 登录慢
ssh远程连接服务器及其缓慢，重启重装sshd无济于事
用ssh -vvv 发登录慢是卡在下面这步：
debug1: Entering interactive session.
后发现在执行机上systemd-logind导致cpu 100%的问题，使得登录异常缓慢，并且消耗资源。
原因
systemd-logind主要功能是为每一个登陆session创建一个systemd角度的cgroup管理对象，更方便对session使用cgroup，在实际场景中没有什么用处，关闭不会影响正常ssh登陆
在有crond任务时，触发systemd-logind回收不及时的bug
解决办法
关闭或重启systemd-logind
systemctl stop systemd-logind
ssh取消超时断开
编辑/etc/ssh/sshd_config
ClientAliveInterval 60
ClientAliveCountMax 3
编辑/etc/profile
添加 TMOUT=0
为0就是设置不超时
免密登录
[root@master ~]# ssh-keygen -t rsa #生成密钥，连续三个回车即可，除非想二次认证，就是使用ssh免密登录时再用密码认证 Generating public/private rsa key pair. Enter file in which to save the key (/root/.ssh/id_rsa): Created directory '/root/.ssh'. Enter passphrase (empty for no passphrase): Enter same passphrase again: Your identification has been saved in /root/.ssh/id_rsa. Your public key has been saved in /root/.ssh/id_rsa.pub. The key fingerprint is: 10:a2:a8:c6:01:f4:21:94:2e:f7:e3:d5:17:4e:a7:53 root@master The key's randomart image is: +--[ RSA 2048]----+ |++... . | |.oo... . | |o... . | |+.o . o E | |o+ . .So = | |. o . . = | | . o . . | | . | | | +-----------------+ [root@master ~]# scp .ssh/id_rsa.pub root@192.168.92.130:/root/.ssh/authorized_keys #将生成的id_rsa.pub传到 B服务器下 The authenticity of host '192.168.92.130 (192.168.92.130)' can't be established. ECDSA key fingerprint is fe:45:19:51:dc:97:92:55:5e:5f:28:cd:b1:28:59:08. Are you sure you want to continue connecting (yes/no)? yes Warning: Permanently added '192.168.92.130' (ECDSA) to the list of known hosts. root@192.168.92.130's password: Permission denied, please try again. root@192.168.92.130's password: id_rsa.pub 100% 393 0.4KB/s 00:00 [root@master ~]# ssh 192.168.92.130 #登录测试，发现已经能直接连接 Last failed login: Thu Mar 26 23:30:22 PDT 2020 from 192.168.92.128 on ssh:notty There was 1 failed login attempt since the last successful login. Last login: Thu Mar 26 22:54:46 2020 from 192.168.92.1 [root@slave-02 ~]#