前言：在inter环境中，过于简单的口令是服务器面临的最大风险。对于任何一个承担这安全责任的管理员，及时找出这些弱口令是非常必要的，这样便于采取进一步的安全措施，
使用John the Ripper 检测Linux、Unix系统用户的密码强度，使用NMAP扫描端口，可以找出网络中不可控的应用服务，及时关闭不安全的服务，减小安全风险。
1、弱口令探测（john the ripper）
1）下载并安装：官方网站是http：//openwall.com/john/,在该网站可以获取最新的稳定版源码包
现在解压安装
[[email protected] ~]# mount /dev/cdrom /media/ mount: block device /dev/sr0 is write-protected, mounting read-only [[email protected] ~]# cd /media/ [[email protected] media]# ls john-1.8.0.tar.tar [[email protected] media]# tar zxf john-1.8.0.tar.tar -C /usr/src/ [[email protected] media]# cd /usr/src/john-1.8.0/ [[email protected] john-1.8.0]# cd src/ [[email protected] src]# pwd /usr/src/john-1.8.0/src [[email protected] src]# make clean linux-x86-64 ......省略编译信息 [[email protected] src]# ls ../run/john //确定已生成可执行程序john ../run/john
John the Ripper 不需要特别的安装操作，编译完成后的run子目录中包括可执行程序John及相关配置文件、字典文件等，可以复制到任何位置使用。
2）检测弱口令
[[email protected] src]# cp /etc/shadow /root/shadow.txt //准备待破解的密码文件 [[email protected] src]# cd ../run [[email protected] run]# ./john /root/shadow.txt //执行暴力破解 0g 0:00:00:42 86% 1/3 0g/s 168.7p/s 168.7c/s 168.7C/s root9999900000..Root000000 0g 0:00:00:43 89% 1/3 0g/s 168.6p/s 168.6c/s 168.6C/s user1555555..u999991982 0g 0:00:00:47 94% 1/3 0g/s 168.6p/s 168.6c/s 168.6C/s 999992010..r999991955 123456 (zhangsan) 123456 (root) 123456 (user1) ......省略部分 ......//按Ctrl+C组合键终止后续过程 [[email protected] run]# ./john --show /root/shadow.txt //查看已破解出的账户列表 root:123456:17552:0:99999:7::: zhangsan:123456:17591:0:30:7::: user1:123456:17592:0:99999:7::: 3 password hashes cracked, 0 left
3）使用密码字典文件破解，默认的字典文件为password.lst
对于密码的暴力破解，字典文件的选择很关键。只要字典文件足够完整，密码破解只是时间问题，
[[email protected] run]# :>john.pot //清空已破解出的账户列表，以便重新分析 [[email protected] run]# ./john --show /root/shadow.txt 0 password hashes cracked, 3 left [[email protected] run]# passwd user1 //修改强密码[email protected] 更改用户 user1 的密码 。 新的 密码： 重新输入新的 密码： passwd： 所有的身份验证令牌已经成功更新。 [[email protected] run]# vim password.lst //将[email protected]写入密码字典里 123456 12345 [email protected] //需要新添加
执行破解(破解之前需要重新拷贝shadow文件)
[[email protected] run]# cp /etc/shadow /root/shadow.txt cp：是否覆盖"/root/shadow.txt"？ y [[email protected] run]# ./john --wordlist=./password.lst /root/shadow.txt Loaded 3 password hashes with 3 different salts (crypt, generic crypt(3) [?/64]) Press 'q' or Ctrl-C to abort, almost any other key for status 123456 (zhangsan) [email protected] (user1) 123456 (root) 3g 0:00:00:01 100% 1.886g/s 60.37p/s 181.1c/s 181.1C/s 123456..pamela Use the "--show" option to display all of the cracked passwords reliably Session completed
2、网络扫描（NMAP）
NMAP是一个强大的端口扫描类安全评测工具，官方网站是http://nmap.org/ NMAP被设计为检测主机数量众多的巨大网络，支持ping扫描、多端口检测、OS识别等多种技术
1）安装NMAP包
[[email protected] ~]# mount /dev/cdrom /media/ mount: block device /dev/sr0 is write-protected, mounting read-only [[email protected] ~]# cd /media/ [[email protected] media]# ls nmap-7.60-1.x86_64.rpm [[email protected] media]# [[email protected] media]# rpm -ivh nmap-7.60-1.x86_64.rpm Preparing... ########################################### [100%] 1:nmap ########################################### [100%]
2）、扫描语法及类型
nmap [扫描类型] [选项] [扫描目标...] 其中，扫描目标可以是主机名、IP地址或网络地址等，多个目标以空格分割；常用的选项有“-p”、“-n”,分别用来指定扫描的端口、禁用反向DNS解析（以加快扫描速度）； 扫描类型决定这检测的方式，也直接影响扫描的结果。 比较常用的几种扫描类型如下： NMAP的扫描语法 nmap [扫描类型] [选项] <扫描目标 ...> 常用的扫描类型 -sS，TCP SYN扫描（半开） -sT，TCP 连接扫描（全开） -sF，TCP FIN扫描 -sU，UDP扫描 -sP，ICMP扫描 -P0，跳过ping检测
3）针对本机进行扫描，检查开放了哪些常用的tcp端口，udp端口
[[email protected] ~]# nmap 127.0.0.1 //扫描常用的TCP端口 Starting Nmap 7.60 ( https://nmap.org ) at 2018-03-03 00:34 CST mass_dns: warning: Unable to determine any DNS servers. Reverse DNS is disabled. Try using --system-dns or specify valid servers with --dns-servers Nmap scan report for localhost (127.0.0.1) Host is up (0.000010s latency). Not shown: 996 closed ports PORT STATE SERVICE 22/tcp open ssh 25/tcp open smtp 111/tcp open rpcbind 631/tcp open ipp Nmap done: 1 IP address (1 host up) scanned in 0.20 seconds 4）扫描常用的udp端口 [[email protected] ~]# nmap -sU 127.0.0.1 //扫描常用的UDP端口 Starting Nmap 7.60 ( https://nmap.org ) at 2018-03-03 00:35 CST mass_dns: warning: Unable to determine any DNS servers. Reverse DNS is disabled. Try using --system-dns or specify valid servers with --dns-servers Nmap scan report for localhost (127.0.0.1) Host is up (0.000028s latency). Not shown: 997 closed ports PORT STATE SERVICE 111/udp open rpcbind 631/udp open|filtered ipp 780/udp open|filtered wpgs Nmap done: 1 IP address (1 host up) scanned in 1.67 seconds
在扫描结果中，STATE列若为open则表示端口为开放状态，为filtered表示为可能被防火墙过滤，为closed表示端口为关闭状态。
[[email protected] ~]# nmap -p 21 192.168.1.0 //检查哪些主机提供FTP服务 Starting Nmap 7.60 ( https://nmap.org ) at 2018-03-03 00:40 CST mass_dns: warning: Unable to determine any DNS servers. Reverse DNS is disabled. Try using --system-dns or specify valid servers with --dns-servers Note: Host seems down. If it is really up, but blocking our ping probes, try -Pn Nmap done: 1 IP address (0 hosts up) scanned in 0.57 seconds [[email protected] ~]# nmap -p 21 192.168.1.0 //检查网段中哪些存活主机（能ping通） Starting Nmap 7.60 ( https://nmap.org ) at 2018-03-03 00:42 CST mass_dns: warning: Unable to determine any DNS servers. Reverse DNS is disabled. Try using --system-dns or specify valid servers with --dns-servers Note: Host seems down. If it is really up, but blocking our ping probes, try -Pn Nmap done: 1 IP address (0 hosts up) scanned in 0.57 seconds
[[email protected] ~]# nmap -p 139,455 192.168.1.1-100 //检查192.168.1.1-100主机是否开启共享服务 Starting Nmap 7.60 ( https://nmap.org ) at 2018-03-03 00:43 CST mass_dns: warning: Unable to determine any DNS servers. Reverse DNS is disabled. Try using --system-dns or specify valid servers with --dns-servers Nmap scan report for 192.168.1.1 Host is up (0.00024s latency). PORT STATE SERVICE 139/tcp closed netbios-ssn 455/tcp closed creativepartnr Nmap scan report for 192.168.1.12 Host is up (0.00016s latency). PORT STATE SERVICE 139/tcp open netbios-ssn 455/tcp closed creativepartnr MAC Address: 00:50:56:C0:00:08 (VMware) Nmap done: 100 IP addresses (2 hosts up) scanned in 1.99 seconds
原文地址：http://blog.51cto.com/13557682/2079942
时间： 2024-09-29 09:36:35