Linux 上 SSH 免密登录

敲击回车键即可，-P 参数表示密码，后面单引号表示空密码。

它在/home/linghu/下生成.ssh 目录，.ssh 下有 id_rsa 和 id_rsa.pub，一个私钥文件一个公钥文件。

2. 把本地机器下的 id_rsa.pub 文件复制到服务器机器下的/用户/.ssh/authorized_keys 文件里，/用户就是登录服务器时使用的用户。

<table border="0" cellpadding="0" cellspacing="0" style="border:1px solid silver; width:1191.19995117188px; border-collapse:collapse; word-break:break-word; bottom:auto!important; float:none!important; height:auto!important; left:auto!important; line-height:1.1em!important; margin:0px!important; outline:0px!important; overflow:visible!important; padding:0px!important; position:static!important; right:auto!important; top:auto!important; vertical-align:baseline!important; font-family:Consolas,'Bitstream Vera Sans Mono','Courier New',Courier,monospace!important; font-size:12px!important; min-height:inherit!important; background:none!important"><tbody style="border:0px!important; bottom:auto!important; float:none!important; height:auto!important; left:auto!important; line-height:1.1em!important; margin:0px!important; outline:0px!important; overflow:visible!important; padding:0px!important; position:static!important; right:auto!important; top:auto!important; vertical-align:baseline!important; width:auto!important; min-height:inherit!important; background:none!important"><tr style="border:0px!important; bottom:auto!important; float:none!important; height:auto!important; left:auto!important; line-height:1.1em!important; margin:0px!important; outline:0px!important; overflow:visible!important; padding:0px!important; position:static!important; right:auto!important; top:auto!important; vertical-align:baseline!important; width:auto!important; min-height:inherit!important; background:none!important"><td class="code" style="border:1px solid silver; padding:3px; border-collapse:collapse; bottom:auto!important; float:none!important; height:auto!important; left:auto!important; line-height:1.1em!important; margin:0px!important; outline:0px!important; overflow:visible!important; position:static!important; right:auto!important; top:auto!important; vertical-align:baseline!important; width:auto!important; font-family:Consolas,'Bitstream Vera Sans Mono','Courier New',Courier,monospace!important; min-height:inherit!important; background:none!important"><div class="container" style="border:0px!important; bottom:auto!important; float:none!important; height:auto!important; left:auto!important; line-height:1.1em!important; margin:0px!important; outline:0px!important; overflow:visible!important; padding:0px!important; position:relative!important; right:auto!important; top:auto!important; vertical-align:baseline!important; width:auto!important; min-height:inherit!important; background:none!important"><div class="line number1 index0 alt2" style="border:0px!important; bottom:auto!important; float:none!important; height:auto!important; left:auto!important; line-height:1.8em!important; margin:0px!important; outline:0px!important; overflow:visible!important; padding:0px 1em 0px 0px!important; position:static!important; right:auto!important; top:auto!important; vertical-align:baseline!important; width:auto!important; min-height:inherit!important; background:none rgb(244,244,244)!important"><code class="csharp plain" style="white-space:pre-wrap; border:0px!important; bottom:auto!important; float:none!important; height:auto!important; left:auto!important; line-height:1.8em!important; margin:0px!important; outline:0px!important; overflow:visible!important; padding:0px!important; position:static!important; right:auto!important; top:auto!important; vertical-align:baseline!important; width:auto!important; font-family:Consolas,'Bitstream Vera Sans Mono','Courier New',Courier,monospace!important; min-height:inherit!important; background:none!important">[linghu@linghu-PC ~]$ scp .ssh/id_rsa.pub yunos@192.168.10.107:/home/yunos/id_rsa.pub.linghu</code></div><div class="line number2 index1 alt1" style="border:0px!important; bottom:auto!important; float:none!important; height:auto!important; left:auto!important; line-height:1.8em!important; margin:0px!important; outline:0px!important; overflow:visible!important; padding:0px 1em 0px 0px!important; position:static!important; right:auto!important; top:auto!important; vertical-align:baseline!important; width:auto!important; min-height:inherit!important"><code class="csharp plain" style="white-space:pre-wrap; border:0px!important; bottom:auto!important; float:none!important; height:auto!important; left:auto!important; line-height:1.8em!important; margin:0px!important; outline:0px!important; overflow:visible!important; padding:0px!important; position:static!important; right:auto!important; top:auto!important; vertical-align:baseline!important; width:auto!important; font-family:Consolas,'Bitstream Vera Sans Mono','Courier New',Courier,monospace!important; min-height:inherit!important; background:none!important">yunos@192.168.10.107's password:</code></div></div></td></tr></tbody></table>

由于还没有免密码登录的，所以要输入密码。

3. 然后将服务器机器的 id_rsa.pub.linghu 内容添加到/用户/.ssh/authorzied_keys 文件里。

<table border="0" cellpadding="0" cellspacing="0" style="border:1px solid silver; width:1191.19995117188px; border-collapse:collapse; word-break:break-word; bottom:auto!important; float:none!important; height:auto!important; left:auto!important; line-height:1.1em!important; margin:0px!important; outline:0px!important; overflow:visible!important; padding:0px!important; position:static!important; right:auto!important; top:auto!important; vertical-align:baseline!important; font-family:Consolas,'Bitstream Vera Sans Mono','Courier New',Courier,monospace!important; font-size:12px!important; min-height:inherit!important; background:none!important"><tbody style="border:0px!important; bottom:auto!important; float:none!important; height:auto!important; left:auto!important; line-height:1.1em!important; margin:0px!important; outline:0px!important; overflow:visible!important; padding:0px!important; position:static!important; right:auto!important; top:auto!important; vertical-align:baseline!important; width:auto!important; min-height:inherit!important; background:none!important"><tr style="border:0px!important; bottom:auto!important; float:none!important; height:auto!important; left:auto!important; line-height:1.1em!important; margin:0px!important; outline:0px!important; overflow:visible!important; padding:0px!important; position:static!important; right:auto!important; top:auto!important; vertical-align:baseline!important; width:auto!important; min-height:inherit!important; background:none!important"><td class="code" style="border:1px solid silver; padding:3px; border-collapse:collapse; bottom:auto!important; float:none!important; height:auto!important; left:auto!important; line-height:1.1em!important; margin:0px!important; outline:0px!important; overflow:visible!important; position:static!important; right:auto!important; top:auto!important; vertical-align:baseline!important; width:auto!important; font-family:Consolas,'Bitstream Vera Sans Mono','Courier New',Courier,monospace!important; min-height:inherit!important; background:none!important"><div class="container" style="border:0px!important; bottom:auto!important; float:none!important; height:auto!important; left:auto!important; line-height:1.1em!important; margin:0px!important; outline:0px!important; overflow:visible!important; padding:0px!important; position:relative!important; right:auto!important; top:auto!important; vertical-align:baseline!important; width:auto!important; min-height:inherit!important; background:none!important"><div class="line number1 index0 alt2" style="border:0px!important; bottom:auto!important; float:none!important; height:auto!important; left:auto!important; line-height:1.8em!important; margin:0px!important; outline:0px!important; overflow:visible!important; padding:0px 1em 0px 0px!important; position:static!important; right:auto!important; top:auto!important; vertical-align:baseline!important; width:auto!important; min-height:inherit!important; background:none rgb(244,244,244)!important"><code class="csharp plain" style="white-space:pre-wrap; border:0px!important; bottom:auto!important; float:none!important; height:auto!important; left:auto!important; line-height:1.8em!important; margin:0px!important; outline:0px!important; overflow:visible!important; padding:0px!important; position:static!important; right:auto!important; top:auto!important; vertical-align:baseline!important; width:auto!important; font-family:Consolas,'Bitstream Vera Sans Mono','Courier New',Courier,monospace!important; min-height:inherit!important; background:none!important">[yunos@yunos-PC ~]$cati{d}_{r}sa.pub.linghu>>.ssh/authorize{d}_{k}eys</code></div><divclass="linenumber2index1alt1"style="border:0px!important;bottom:auto!important;float:none!important;height:auto!important;left:auto!important;line-height:1.8em!important;margin:0px!important;outline:0px!important;overflow:visible!important;padding:0px1em0px0px!important;position:static!important;right:auto!important;top:auto!important;vertical-align:baseline!important;width:auto!important;min-height:inherit!important"><codeclass="csharpplain"style="white-space:pre-wrap;border:0px!important;bottom:auto!important;float:none!important;height:auto!important;left:auto!important;line-height:1.8em!important;margin:0px!important;outline:0px!important;overflow:visible!important;padding:0px!important;position:static!important;right:auto!important;top:auto!important;vertical-align:baseline!important;width:auto!important;font-family:Consolas{,}^{\prime }BitstreamVeraSansMon{o}^{\prime }{,}^{\prime }CourierNe{w}^{\prime },Courier,monospace!important;min-height:inherit!important;background:none!important">[yunos@yunos-PC]$ chmod 600 .ssh/authorized_keys</code></div></div></td></tr></tbody></table>

authorized_keys 的权限要是 600。

4. 本地机器免密登录服务器。

<table border="0" cellpadding="0" cellspacing="0" style="border:1px solid silver; width:1191.19995117188px; border-collapse:collapse; word-break:break-word; bottom:auto!important; float:none!important; height:auto!important; left:auto!important; line-height:1.1em!important; margin:0px!important; outline:0px!important; overflow:visible!important; padding:0px!important; position:static!important; right:auto!important; top:auto!important; vertical-align:baseline!important;

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font-family:Consolas,'Bitstream Vera Sans Mono','Courier New',Courier,monospace!important; font-size:12px!important; min-height:inherit!important; background:none!important"><tbody style="border:0px!important; bottom:auto!important; float:none!important; height:auto!important; left:auto!important; line-height:1.1em!important; margin:0px!important; outline:0px!important; overflow:visible!important; padding:0px!important; position:static!important; right:auto!important; top:auto!important; vertical-align:baseline!important; width:auto!important; min-height:inherit!important; background:none!important"><tr style="border:0px!important; bottom:auto!important; float:none!important; height:auto!important; left:auto!important; line-height:1.1em!important; margin:0px!important; outline:0px!important; overflow:visible!important; padding:0px!important; position:static!important; right:auto!important; top:auto!important; vertical-align:baseline!important; width:auto!important; min-height:inherit!important; background:none!important"><td class="code" style="border:1px solid silver; padding:3px; border-collapse:collapse; bottom:auto!important; float:none!important; height:auto!important; left:auto!important; line-height:1.1em!important; margin:0px!important; outline:0px!important; overflow:visible!important; position:static!important; right:auto!important; top:auto!important; vertical-align:baseline!important; width:auto!important; font-family:Consolas,'Bitstream Vera Sans Mono','Courier New',Courier,monospace!important; min-height:inherit!important; background:none!important"><div class="container" style="border:0px!important; bottom:auto!important; float:none!important; height:auto!important; left:auto!important; line-height:1.1em!important; margin:0px!important; outline:0px!important; overflow:visible!important; padding:0px!important; position:relative!important; right:auto!important; top:auto!important; vertical-align:baseline!important; width:auto!important; min-height:inherit!important; background:none!important"><div class="line number1 index0 alt2" style="border:0px!important; bottom:auto!important; float:none!important; height:auto!important; left:auto!important; line-height:1.8em!important; margin:0px!important; outline:0px!important; overflow:visible!important; padding:0px 1em 0px 0px!important; position:static!important; right:auto!important; top:auto!important; vertical-align:baseline!important; width:auto!important; min-height:inherit!important; background:none rgb(244,244,244)!important"><code class="csharp plain" style="white-space:pre-wrap; border:0px!important; bottom:auto!important; float:none!important; height:auto!important; left:auto!important; line-height:1.8em!important; margin:0px!important; outline:0px!important; overflow:visible!important; padding:0px!important; position:static!important; right:auto!important; top:auto!important; vertical-align:baseline!important; width:auto!important; font-family:Consolas,'Bitstream Vera Sans Mono','Courier New',Courier,monospace!important; min-height:inherit!important; background:none!important">[linghu@linghu-PC ~]$ ssh 192.168.10.107</code></div></div></td></tr></tbody></table>第一次登录是时要你输入 yes。 现在本地机器可以无密码登录服务器机器了。

小结：登录的机子可有私钥，被登录的机子要有登录机子的公钥。这个公钥/私钥对一般在私钥宿主机产生。上面是用 rsa 算法的公钥/私钥对，当然也可以用 dsa(对应的文件是 id_dsa，id_dsa.pub)。