windows putty 連接到 linux 免密碼

目標：system1透過ssh鏈接到system2電腦

• 生成 private key (id_rsa) & public key (id_rsa.pub)
• id_rsa是system1要用的，例如windows端
• id_rsa.pub是你要連過去system2要用的, 此服務器必須安裝openssh-server服務(sshd)
• 把id_rsa.pub append到system2的 ~/.ssh/authorized_keys 文件裏面
• 並要清楚登入服務器的username，例如root
• 找一臺能夠運行 ssh-keygen 的環境, windows可用Cygwin

步驟以下：

# ssh-keygen -t rsa
Enter file in which to save the key (~/.ssh/id_rsa): Created directory '~/.ssh'. Enter passphrase (empty for no passphrase): Enter same passphrase again: Your identification has been saved in ~/.ssh/id_rsa. Your public key has been saved in ~/.ssh/id_rsa.pub. The key fingerprint is: 1c:fe:8d:10:b5:32:09:95:51:48:df:45:ef:74:5d:dc henry@db0222da7529 The key's randomart image is: +--[ RSA 2048]----+ | .o+=o .o.o| | .o+ o . .E| | * o . =| | o = o.| | S .| | o o | | o . | | | | | +-----------------+

ssh-keygen的參數說明：

-t type
  Specifies the type of key to create. The possible values are
  ``rsa1'' for protocol version 1 and ``dsa'', ``ecdsa'' or ``rsa''
  for protocol version 2.

# cat ~/.ssh/id_rsa.pub > ~/.ssh/authorized_keys

注意: 用putty自帶的PUTTYGEN.EXE生成會不兼容OpenSSH，從而會致使登陸時出現server refused our key錯誤

作法: 把private key(id_rsa)給拷貝出來，我是用vim或cat來開啓id_rsa文件而後用鼠標按右鍵拷到windows下的剪貼板, 存到一個文本給PUTTYGEN.EXE File/Load private key使用. 接着點擊Save private key, 此檔案等下要用.

1.開啓putty.exe, 設定Connection/data/Auto-login username, 這裏我是用root來登入

2.SSH/Auth/Private key file for authentication:點擊Browser選擇到你保存私鑰(.pkk)的文件, 就是 Save private key 的那個檔案.