让我们看看如何在Linux系统上更新或者更改SSH密钥密码短语。
SSH键通常用于对用户进行身份验证到某种信息系统。
SSH键自己是私钥;使用从密码级派生的对称加密密钥进一步加密私钥。
很容易在Linux/UNIX系统上更改SSH密钥密码短语。

什么是ssh密钥密码？

密码短语类似于密码，用于保护SSH私钥免于未经授权的访问和使用情况。
始终建议为SSH键设置一个强大的密码，至少15个，最好是20个字符，并且难以猜测。

如何在Linux/UNIX上更改或者更新SSH密钥密码短语

有时我们可能需要更新SSH密钥密码短语，如果我们在生成SSH键时未设置，则会设置一个。

作为一个例子，让我们在没有密码短语的情况下生成ssh键：

# ssh-keygen 
Generating public/private rsa key pair.
Enter file in which to save the key (/root/.ssh/id_rsa): 
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:
SHA256:1gSD3mPgxaD0C88YLU+TdYs2T3nBO5ttK5Jj0bvz0gs Hyman@theitroad
The key's randomart image is:
+---[RSA 2048]----+
|    . .++ ...    |
|   . +ooo= o..   |
|    =o*++ = ..   |
|     Xo++* .o    |
|    . =.S.o. =   |
|       .  . + o  |
|           oE+ . |
|          = =.o  |
|         . o.*o. |
+----[SHA256]-----+

现在使用下面的命令设置密码短语：

# ssh-keygen -p -f ~/.ssh/id_rsa
Enter new passphrase (empty for no passphrase): <Enter passphrase>
Enter same passphrase again:<Retype passphrase>
Your identification has been saved with the new passphrase.

如果使用私钥的自定义路径，请更换 ~/.ssh/id_rsa使用私钥的路径。

重置密码时相同的命令适用，我们将被要求旧的，并将新的命令设置。

# ssh-keygen -p -f ~/.ssh/id_rsa
Enter old passphrase: <Enter old passphrase>
Enter new passphrase (empty for no passphrase): <Enter new passphrase> 
Enter same passphrase again: <Retype new passphrase>
Your identification has been saved with the new passphrase.

测试新密码

要测试新密码是工作的，将SSH公钥复制到远程服务器并尝试使用它进行SSH。

$ssh-copy-id Hyman@theitroad
Enter passphrase for key '/home/jmutai/.ssh/id_rsa': 
Now try logging into the machine, with "ssh 'Hyman@theitroad'", and check in:
.ssh/authorized_keys
to make sure we haven't added extra keys that you weren't expecting.

保存私钥密码

使用SSH，我们可以配置身份验证代理以保存密码，以便每次使用SSH键时都不必重新输入密码。

# Start agent on demand
eval $(ssh-agent) 
# Add default key
ssh-add 
# List keys
ssh-add -l 
# Add specific key
ssh-add ~/.ssh/id_rsa 
# Add with timeout
ssh-add -t 3600 ~/.ssh/id_rsa
# Drop keys
ssh-add -D