![\"SSH](\"https:\/\/linuxadmin.io\/wp-content\/uploads\/2017\/07\/ssh-key-generation-1.png\")
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SSH key authentication can be used for password-less login between 2 servers. This is also useful for adding a key to accounts like git or gitlab for version management.<\/p>\n
Generate a RSA key for this system by typing the following<\/p>\n
ssh-keygen -t rsa<\/p>\n
The key generated will ask for a location to store the newly created key, the default is the home directory of the user creating it under the .ssh directory. It will also ask you for a password which you optionally leave blank.<\/p>\n
On the source server you can use ssh-copy-id to copy over the id_rsa.pub file to the new server. It will use the SSH protocol to copy over the public key and insert it into the authorized_keys file on the destination server. To read more about ssh-copy-id you can read the man page<\/a>.<\/p>\n ssh-copy-id -i ~\/.ssh\/id_rsa.pub [email protected]<\/a>Replacing 192.168.1.3 with the appropriate host name of the destination server and user with the user you would like to add the key too.<\/p>\n \/bin\/ssh-copy-id: INFO: attempting to log in with the new key(s), to filter out any that are already installed Number of key(s) added: 1<\/p>\n Now try logging into the machine, with: “ssh ‘[email protected]<\/a>‘” First verify if you already have a .ssh directory<\/p>\n ls ~\/.ssh<\/p>\n If you do not you will want to create the following directory<\/p>\n mkdir ~\/.ssh<\/p>\n You will also want to create authorized_keys file<\/p>\n touch ~\/.ssh\/authorized_keys<\/p>\n You will then want to copy the public key from the source server in to the authorized_keys file. You can do this by copying the id_rsa.pub on the source server.<\/p>\n scp ~\/.ssh\/id_rsa.pub [email protected]<\/a>_host:~\/.ssh\/authorized_keys<\/p>\n If you are adding keys to a root user on the destination server, you will want to ensure the sshd configuration allows remote root logins with either the following 2 options enabled in \/etc\/ssh\/sshd_config<\/p>\n PermitRootLogin yes<\/p>\n Which will allow root logins with both passwords and keys.<\/p>\n PermitRootLogin without-password<\/p>\n Which will allow root logins only with keys<\/p>\n If you modify the ssh configuration, you will need to reload sshd to load the new configuration<\/p>\n \/etc\/init.d\/sshd reload<\/p>\n After you have added the key to the destination server, ssh from the source server it should allow you to login using the key.<\/p>\n Jul 4, 2017LinuxAdmin.io<\/p>\n
\n\/bin\/ssh-copy-id: INFO: 1 key(s) remain to be installed — if you are prompted now it is to install the new keys
\n[email protected]<\/a>‘s password:<\/p>\n
\nand check to make sure that only the key(s) you wanted were added.<\/p>\nManual SSH Key Configuration on the Destination Server<\/h2>\n
Root SSH Key Configuration<\/h2>\n