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***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，讓他可以指定不同的service port 。

[root@rong2 .ssh]# cp /usr/bin/ssh-copy-id /usr/bin/ssh-copy-id.new
[root@rong2 .ssh]# vim /usr/bin/ssh-copy-id.new
#!/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 <      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





执行带port的命令：
[root@rong2 .ssh]# ssh-copy-id.new -i id_rsa.pub -p 2222 [email protected]
The authenticity of host '192.168.0.2 (192.168.0.2)' can't be established.
RSA key fingerprint is f6:8e:f2:7c:0c:f2:33:5d:58:5e:29:0f:a5:82:8e:a2.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added '192.168.0.2' (RSA) to the list of known hosts.
reverse mapping checking getaddrinfo for bogon failed - POSSIBLE BREAK-IN ATTEMPT!
[email protected]'s password:
      Now try logging into the machine, with "ssh -p 2222 '[email protected]'", and check
in:
     
        .ssh/authorized_keys
     
      to make sure we haven't added extra keys that you weren't expecting.
     
      EOF