SSH通过密钥登录服务器，无须输入登录密码(非22端口）
ssh-copy-id的 使用
????? ssh-copy-id是ssh client套件内一个预设的指令，简单的来说他只是一个script，当你在本机 电脑已经有产生了RSA or DSA? authentication，可以透过ssh-copy-id的指令将认证传送到 远端主机。
????? 如何建立RSA or DSA authentication？
?$ ssh-keygen -t dsa (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的差异????
??? ? 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来建立authentication。
ssh-copy-id的 运用
????? $ ssh-copy-id.orig -i ~/.ssh/id_dsa.pub wawa@remotehost
????? wawa@remotehost's password: (需要输入一次密码)
????? Now try logging into the machine, with "ssh 'wawa@remotehost'", and check
????? in:
??????? .ssh/authorized_keys
????? to make sure we haven't added extra keys that you weren't expecting.
?????
???? 简单的执行 ssh-copy-id.orig -i 认证档案 帐号@主机
?????就可以完成认证，之后就可以直接不敲密码就ssh连线到远端主机
?? 基本上对外服务的主机，ssh listen port都会改掉预设的22 port，如此一来可以减少主机被入侵的机会，更改ssh listen port是最基本的第一道防线，请将设定档内的 Port 22 进行更改，并且重新启动ssh的服务。
?? 但是当您改掉ssh listen port之后，ssh-copy-id这个好用的指令将无法运用， 这样一来不是很可惜吗？于是我们就可以对ssh-copy-id这个script进行一 些修改，让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的设定进去，建议可以直接复制贴上取代即可。
????? 以上script参考来源：http://blog.vieth.biz/2009/03/23/ssh-copy-id-with-port/
?ssh-copy-id with port的运用
????? $ ssh-copy-id -i ~/.ssh/id_dsa.pub -p 1234 wawa@remotehost
????? wawa@remotehost's password: (需要输入一次密码)
????? Now try logging into the machine, with "ssh -p 1234 'wawa@remotehost'",
????? 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的认证就完成啰！
转自：http://blog.csdn.net/Johnvikey/archive/2010/05/28/5630548.aspx
以上操作和脚本均在CentOS 5.x和6.x下均测试通过，转载以备日后查用。
?
常见问题：权限方面，须要保证在服务器端，authorized_keys能被other用户读取到，否则会提示输入密码，仍不能自动登录，如：
[usr@target ~]$ ll .ssh/
总计 4
-rw----r-- 1 usr usr 610 12-05 10:11 authorized_keys
