环境：
系统版本：
[root@localhost ~]# cat /etc/redhat-release CentOS Linux release 7.5.1804 (Core) //Centos 7.5系统
安装SSH：
[root@localhost ~]# rpm -qa | grep ssh //是否安装ssh openssh-7.4p1-16.el7.x86_64 openssh-clients-7.4p1-16.el7.x86_64 openssh-server-7.4p1-16.el7.x86_64 libssh2-1.4.3-10.el7_2.1.x86_64
主机：
目标服务器：192.168.2.161 源服务器：192.168.2.195
配置免密：
1.在源服务器端生成密钥
[root@localhost ~]# ssh-keygen -t rsa //无需配置，一路回车 Generating public/private rsa key pair. Enter file in which to save the key (/root/.ssh/id_rsa): /root/.ssh/id_rsa already exists. 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:`[root@localhost ~]# ls ./.ssh/ authorized_keys id_rsa id_rsa.pub known_hosts` SHA256:8vvhVMFr1nPngJkod+CoCBfDxD2aCcO1duiXW9dZE6Y root@localhost.localdomain The key's randomart image is: +---[RSA 2048]----+ | . oo. o | | +o.oo . o . | | oB+.. . E o | | o++ . o + X . | | . o + S = % + o| | o o * + = =.| | . o . o .| | + . | | ..o | +----[SHA256]-----+
2.查看生成的公私钥
[root@localhost ~]# ls ./.ssh/ authorized_keys id_rsa id_rsa.pub known_hosts
- id_rsa 私钥
- id_rsa.pub 公钥
3.上传公钥至目标服务器端
[root@localhost ~]# ssh-copy-id -i ./.ssh/id_rsa.pub root@192.168.2.161 /usr/bin/ssh-copy-id: INFO: Source of key(s) to be installed: "./.ssh/id_rsa.pub" /usr/bin/ssh-copy-id: INFO: attempting to log in with the new key(s), to filter out any that are already installed /usr/bin/ssh-copy-id: INFO: 1 key(s) remain to be installed -- if you are prompted now it is to install the new keys root@192.168.2.161's password: Number of key(s) added: 1 Now try logging into the machine, with: "ssh 'root@192.168.2.161'" and check to make sure that only the key(s) you wanted were added.
4.测试免密登录目标服务器端
[root@localhost ~]# ssh root@192.168.2.161 //成功免密登录 Last login: Tue Mar 24 17:03:27 2020 from 192.168.2.161
小结：
以上配置只是单向免密，如果需要配置目标服务器与源服务器之间互相免密登录，需要在目标服务器上做同样的操作，将公钥上传至源服务器端即可。
