ssh-keygen
generates public and private key pairs.
ssh-copy-id
copies the local public key to the authorized_keys file of the remote machine. ssh-copy-id also gives you access to the remote machine's home, ~./ssh , and ~/.ssh/authorized_keys
Step 1: Use ssh-keygen on the local machine to generate a public and private key pair
- jsmith@local-host$ [Note: You are on local-host here]
- jsmith@local-host$ ssh-keygen
- Generating public/private rsa key pair.
- Enter file in which to save the key (/home/jsmith/.ssh/id_rsa):[Enter key]
- Enter passphrase (empty for no passphrase): [Press enter key]
- Enter same passphrase again: [Pess enter key]
- Your identification has been saved in /home/jsmith/.ssh/id_rsa.
- Your public key has been saved in /home/jsmith/.ssh/id_rsa.pub.
- The key fingerprint is:
- 33:b3:fe:af:95:95:18:11:31:d5:de:96:2f:f2:35:f9 jsmith@local-host
- jsmith@local-host$ ssh-copy-id -i ~/.ssh/id_rsa.pub remote-host
- jsmith@remote-host's password:
- Now try logging into the machine, with "ssh 'remote-host'", and check in:
- .ssh/authorized_keys
- to make sure we haven't added extra keys that you weren't expecting.
Note: ssh-copy-id writes the key to the ~/ .ssh/authorized_key. file on the remote machine
Step 3: Log in to the remote machine without entering a password- jsmith@local-host$ ssh remote-host
- Last login: Sun Nov 16 17:22:33 2008 from 192.168.1.2
- [Note: SSH did not ask for password.]
- jsmith@remote-host$ [Note: You are on remote-host here]
common problem:
- ssh-copy-id -u eucalyptus -i ~eucalyptus/.ssh/id_rsa.pub eucalyptus@remote_host
The above is to give eucalyptus users the right to log in without a password
[1]
- /usr/bin/ssh-copy-id: ERROR: No identities found
使用选项 -i ，当没有值传递的时候或者 如果 ~/.ssh/identity.pub 文件不可访问（不存在）, ssh-copy-id 将显示上述的错误信息 （ -i选项会优先使用将ssh-add -L的内容）
- jsmith@local-host$ ssh-agent $SHELL
- jsmith@local-host$ ssh-add -L
- The agent has no identities.
- jsmith@local-host$ ssh-add
- Identity added: /home/jsmith/.ssh/id_rsa (/home/jsmith/.ssh/id_rsa)
- jsmith@local-host$ ssh-add -L
- ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEAsJIEILxftj8aSxMa3d8t6JvM79DyBV
- aHrtPhTYpq7kIEMUNzApnyxsHpH1tQ/Ow== /home/jsmith/.ssh/id_rsa
- jsmith@local-host$ ssh-copy-id -i remote-host
- jsmith@remote-host's password:
- Now try logging into the machine, with "ssh 'remote-host'", and check in:
- .ssh/authorized_keys
- to make sure we haven't added extra keys that you weren't expecting.
- [Note: This has added the key displayed by ssh-add -L]
[2] ssh-copy-id应注意的三个小地方
- Default public key: ssh-copy-id uses ~/.ssh/identity.pub as the default public key file (i.e when no value is passed to option -i). Instead, I wish it uses id_dsa.pub, or id_rsa.pub, or identity.pub as default keys. i.e If any one of them exist, it should copy that to the remote-host. If two or three of them exist, it should copy identity.pub as default.
- The agent has no identities: When the ssh-agent is running and the ssh-add -L returns “The agent has no identities” (i.e no keys are added to the ssh-agent), the ssh-copy-id will still copy the message “The agent has no identities” to the remote-host’s authorized_keys entry.
- Duplicate entry in authorized_keys: I wish ssh-copy-id validates duplicate entry on the remote-host’s authorized_keys. If you execute ssh-copy-id multiple times on the local-host, it will keep appending the same key on the remote-host’s authorized_keys file without checking for duplicates. Even with duplicate entries everything works as expected. But, I would like to have my authorized_keys file clutter free.