打造坚固的安全的Linux服务器(ssh登录篇)
Nov 3 01:22:06 server sshd[11879]: Failed password for root from 123.127.5.131 port 38917 ssh2
Nov 3 01:22:17 server sshd[11880]: Received disconnect from 123.127.5.131: 13: The user canceled authentication.
Nov 3 03:15:08 server sshd[17524]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=2
4.238.47.93.res-cmts.tv13.ptd.net user=root
Nov 3 03:15:11 server sshd[17524]: Failed password for root from 24.238.47.93 port 3033 ssh2
Nov 3 03:15:11 server sshd[17525]: Received disconnect from 24.238.47.93: 11: Bye Bye
Nov 3 05:14:12 server sshd[20460]: Invalid user a from 218.28.4.61
Nov 3 05:14:12 server sshd[20460]: Address 218.28.4.61 maps to pc0.zz.ha.cn, but this does not map back to the address - POS
SIBLE BREAK-IN ATTEMPT!
Nov 3 05:14:12 server sshd[20461]: input_userauth_request: invalid user a
Nov 3 05:14:12 server sshd[20460]: pam_unix(sshd:auth): check pass; user unknown
Nov 3 05:14:12 server sshd[20460]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=2
18.28.4.61
Nov 3 05:14:14 server sshd[20460]: Failed password for invalid user a from 218.28.4.61 port 15683 ssh2
Nov 3 05:14:14 server sshd[20461]: Received disconnect from 218.28.4.61: 11: Bye Bye
Nov 3 05:14:16 server sshd[20467]: Invalid user 1 from 218.28.4.61
Nov 3 05:14:16 server sshd[20467]: Address 218.28.4.61 maps to pc0.zz.ha.cn, but this does not map back to the address - POS
SIBLE BREAK-IN ATTEMPT!
Nov 3 05:14:16 server sshd[20468]: input_userauth_request: invalid user 1
Nov 3 05:14:16 server sshd[20467]: pam_unix(sshd:auth): check pass; user unknown
Nov 3 05:14:16 server sshd[20467]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=2
18.28.4.61
Nov 3 05:14:18 server sshd[20467]: Failed password for invalid user 1 from 218.28.4.61 port 15817 ssh2
Nov 3 05:14:18 server sshd[20468]: Received disconnect from 218.28.4.61: 11: Bye Bye
Nov 3 05:14:20 server sshd[20473]: Address 218.28.4.61 maps to pc0.zz.ha.cn, but this does not map back to the address - POS
SIBLE BREAK-IN ATTEMPT!
Nov 3 05:14:20 server sshd[20473]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=2
18.28.4.61 user=root
Nov 3 05:14:22 server sshd[20473]: Failed password for root from 218.28.4.61 port 15940 ssh2
Nov 3 05:14:22 server sshd[20475]: Received disconnect from 218.28.4.61: 11: Bye Bye
Nov 3 05:14:24 server sshd[21504]: Address 218.28.4.61 maps to pc0.zz.ha.cn, but this does not map back to the address - POS
SIBLE BREAK-IN ATTEMPT!
更多的是类似这样的：
Nov 4 13:09:44 server sshd[9319]: Did not receive identification string from 66.197.176.130
Nov 4 13:15:24 server sshd[10015]: Did not receive identification string from UNKNOWN
Nov 4 13:16:25 server sshd[10200]: Did not receive identification string from UNKNOWN
Nov 4 13:18:28 server sshd[11524]: Did not receive identification string from UNKNOWN
Nov 4 13:19:24 server sshd[11579]: Did not receive identification string from UNKNOWN
Nov 4 13:20:24 server sshd[11707]: Did not receive identification string from UNKNOWN
Nov 4 13:21:24 server sshd[11782]: Did not receive identification string from UNKNOWN
Nov 4 13:22:24 server sshd[11854]: Did not receive identification string from UNKNOWN
Nov 4 13:24:26 server sshd[12036]: Did not receive identification string from UNKNOWN
Nov 4 13:25:26 server sshd[12201]: Did not receive identification string from UNKNOWN
Nov 4 13:26:26 server sshd[13312]: Did not receive identification string from UNKNOWN
Nov 4 13:27:26 server sshd[13400]: Did not receive identification string from UNKNOWN
Nov 4 13:28:26 server sshd[13542]: Did not receive identification string from UNKNOWN
看来安全问题不少，呵呵。于是开始行动，加固安全防线，打造一个安全的服务器，让老美黑客们也歇菜，哈哈。
首先，禁用root 远程登录，改ssh端口
vi /etc/ssh/sshd_config
PermitRootLogin no #禁用root 登录，创建一个普通用户用作远程登录，然后通过su -转为root 用户
#Port 22
Port 36301 #改到一般扫描器扫到累死才能找到的端口（从20 扫到 36301 … 哈哈）
重启 /etc/init.d/sshd restart
上述更改后，安全日志好几天没有动静，除了我自己登录的日志外，成果初现。不过好景不长，过几天后又发现有一试探登录日志：
Nov 9 15:57:02 server sshd[13948]: Did not receive identification string from 66.197.176.130
Nov 9 15:57:02 server sshd[13916]: Did not receive identification string from 66.197.176.130
Nov 9 15:57:02 server sshd[13949]: Did not receive identification string from 66.197.176.130
Nov 9 15:57:02 server sshd[13944]: Did not receive identification string from 66.197.176.130
Nov 9 22:58:17 server sshd[15736]: Did not receive identification string from UNKNOWN
Nov 9 22:59:17 server sshd[15972]: Did not receive identification string from UNKNOWN
Nov 9 23:00:18 server sshd[16163]: Did not receive identification string from UNKNOWN
Nov 9 23:01:18 server sshd[16309]: Did not receive identification string from UNKNOWN
Nov 9 23:02:18 server sshd[17579]: Did not receive identification string from UNKNOWN
Nov 9 23:03:18 server sshd[17736]: Did not receive identification string from UNKNOWN
Nov 9 23:04:17 server sshd[17846]: Did not receive identification string from UNKNOWN
Nov 9 23:05:17 server sshd[18021]: Did not receive identification string from UNKNOWN
Nov 9 23:06:20 server sshd[18103]: Did not receive identification string from UNKNOWN
Nov 9 23:07:20 server sshd[18166]: Did not receive identification string from UNKNOWN
Nov 9 23:08:20 server sshd[18307]: Did not receive identification string from UNKNOWN
嗯，看来这是一位执着的黑客，他的执着没有白费，终于找到我的ssh新端口。（my god,从22 扫描到36301需要多长时间？？？），看来我只能使出我的杀手剪了。封IP