ssk-keygen + ssh-copy-id 无密码登陆远程LINUX主机

女爷i 2022-08-06 08:15 209阅读 0赞

ssh-copy-id是ssh client套件內一个预设的指令，简单的来说他只是一个script，当你在本地主机已经产生了RSA /DSA和authentication，可以通过ssh-copy-id的指令将认证傳送到远端主机。

如何建立RSA /DSA和authentication？

$ ssh-keygen -t dsa 或者ssh-keygen -t rsa

Generating public/private dsa key pair.

Enter file in which to save the key (/root/.ssh/id\_dsa)

RSA与DSA的差别

ssh-keygen can create RSA keys for use by SSH protocol version 1 and RSA  or DSA keys for use by SSH protocol version 2

简单来说，若您只使用SSH protocol version 2，建议使用DSA來建立authentication。

使用下例中ssk-keygen和ssh-copy-id，仅需通过3个步骤的简单设置而无需输入密码就能登录远程Linux主机。

ssh-keygen 创建公钥和密钥。   
ssh-copy-id 把本地主机的公钥复制到远程主机的authorized\_keys文件上。  
ssh-copy-id 也会给远程主机的用户主目录（home）和~/.ssh, 和~/.ssh/authorized\_keys设置合适的权限 。  
  
步骤1: 用 ssh-key-gen 在本地主机上创建公钥和密钥  
ligh@local-host$ ssh-keygen -t  rsa  
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   
ligh@local-host  
  
步骤2: 用 ssh-copy-id 把公钥复制到远程主机上（ssh-copy-id -i 认证档案 用户名@主机）  
ligh@local-host$ ssh-copy-id -i ~/.ssh/id\_rsa.pub  boon@211.87.227.248  
ligh@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.  
\[注: ssh-copy-id 把密钥追加到远程主机的 .ssh/authorized\_key 上.\]  
  
步骤3: 直接登录远程主机  
ligh@local-host$ ssh remote-host   
Last login: Sun Nov 16 17:22:33 2008 from 192.168.1.2   
\[注: SSH 不会询问密码.\]

ligh@remote-host$

对22端口的修改问题：

基本上對外服務的主機，ssh listen port都會改掉預設的22 port，如此一來可以減少主機被入侵的機會，更改ssh listen port是最基本的第一道防線，請將設定檔內的 Port 22 進行更改，並且重新啟動ssh的服務。

但是當您改掉ssh listen port之後，ssh-copy-id這個好用的指令將無法運用，這樣一來不是很可惜嗎？於是我們就可以對ssh-copy-id這個script進行一些修改，讓他可以支援指定不同的service port 。

更改ssh-copy-id

$ cp /usr/bin/ssh-copy-id /usr/bin/ssh-copy-id.orig  
      $ vi /usr/bin/ssh-copy-id

\#!/bin/sh  
         
      \# Shell script to install your identity.pub on a remote machine  
      \# Takes the remote machine name as an argument.  
      \# Obviously, the remote machine must accept password authentication,  
      \# or one of the other keys in your ssh-agent, for this to work.  
         
      ID\_FILE="$\{HOME\}/.ssh/identity.pub"  
         
      while getopts ':i:p:P:h' OPTION  
      do  
          case $OPTION in  
              i)  
              if \[ -n "$OPTARG" \]; then  
                  if expr "$OPTARG" : ".\*.pub" > /dev/null ; then  
                      ID\_FILE="$OPTARG"  
                  else  
                      ID\_FILE="$OPTARG.pub"  
                  fi  
              fi  
              ;;  
              P|p)  
                  PORT=$OPTARG;  
              ;;  
              h)  
                  echo "Usage: $0 \[-i \[identity\_file\]\] \[user@\]machine" >&2  
                  exit 1  
              ;;  
          esac;  
      done;  
         
      shift $(($OPTIND - 1))  
         
      if \[ $\# -lt 1 \] && \[ x$SSH\_AUTH\_SOCK != x \] ; then  
         GET\_ID="$GET\_ID ssh-add -L"  
      fi  
         
      if \[ -z "\`eval $GET\_ID\`" \] && \[ -r "$\{ID\_FILE\}" \] ; then  
        GET\_ID="cat $\{ID\_FILE\}"  
      fi  
         
      if \[ -z "\`eval $GET\_ID\`" \]; then  
        echo "$0: ERROR: No identities found" >&2  
        exit 1  
      fi  
         
      if \[ -z $PORT \]; then  
          PORTOPTION=""  
      else  
          PORTOPTION="-p $PORT "  
      fi;  
         
      \{ eval "$GET\_ID" ; \} | ssh $PORTOPTION $1 "umask 077; test -d .ssh ||   
      mkdir .ssh ; cat >> .ssh/authorized\_keys" || exit 1  
         
      cat <<EOF  
      Now try logging into the machine, with "ssh $PORTOPTION'$1'", and check   
in:  
         
        .ssh/authorized\_keys  
         
      to make sure we haven't added extra keys that you weren't expecting.  
         
      EOF

主要是增加了port的設定進去，建議可以直接複製貼上取代即可。  
      以上script參考來源：[http://blog.vieth.biz/2009/03/23/ssh-copy-id-with-port/][http_blog.vieth.biz_2009_03_23_ssh-copy-id-with-port]

ssh-copy-id with port的運用

$ ssh-copy-id -i ~/.ssh/id\_dsa.pub -p 1234 boon[@][Link 1]tunnel.sdboon  
      [wawa@remotehost's][wawa_remotehost_s] password: (需要輸入一次密碼)  
      Now try logging into the machine, with "ssh -p 22222 ['boon@tunnel.sdboon'][boon_tunnel.sdboon]", and check in:  
         
        .ssh/authorized\_keys  
         
      to make sure we haven't added extra keys that you weren't expecting.

ssh-copy-id with port的認證就完成囉！

[http_blog.vieth.biz_2009_03_23_ssh-copy-id-with-port]: http://blog.vieth.biz/2009/03/23/ssh-copy-id-with-port/
[Link 1]: mailto:wawa@remotehost
[wawa_remotehost_s]: mailto:wawa@remotehost'%20rel=
[boon_tunnel.sdboon]: mailto:'%20rel=