信息安全
这两天突然发现我们的服务器产生大量DNS解析连线。为了查明问题，就下载网上找工具检查问题所在。用了两个工具，一个chkrootkit，另外一个rootkit huntur。在使用了这两个产品后，觉得rootkit的信息更加详细一些。现在就对两个工具的操作和使用写一个记录，也方便之后自己查看。
1. chkrootkit的使用
1.1 解压安装
#tar -zxvf chkrootkit.tar.gz
#make sense
1.2 运行监测
#./chkrootkit
运行结果在
判断有问题的信息如下：
Checking `ifconfig'... INFECTED
Checking `ls'... INFECTED
Checking `netstat'... INFECTED
Checking `ps'... INFECTED
Checking `top'... INFECTED
Searching for Madalin rootkit default files... Possible Madalin rootkit installed
Checking `bindshell'... INFECTED (PORTS: 145)
Checking `lkm'... You have 77 process hidden for readdir command
You have 77 process hidden for ps command
chkproc: Warning: Possible LKM Trojan installed
Checking `sniffer'... eth0: PROMISC
不幸中招，系统只能够重新安装了。在看了这个文档之后，对chkrootkit这个工具又看了一些其他资料。可以做rootkit的自动检查操作
1.3 chkrootkit参数说明
Usage: ./chkrootkit [options] [test ...]
Options:
-h 显示帮助信息
-V 显示版本信息
-l 显示测试内容
-d debug模式，显示检测过程的相关指令程序
-q 安静模式，只显示有问题部分，
-x 高级模式，显示所有检测结果
-r dir 设定指定的目录为根目录
-p dir1:dir2:dirN 检测指定目录
-n 跳过NFS连接的目录
2.1 解压安装
解压
#tar -zxvf rkhunter-1.3.4.tar.gz
安装
#cd rkhunter-1.3.4
#./installer.sh -h
Usage: ./installer.sh <parameters>
Ordered valid parameters:
--help (-h) : 显示帮助
--examples : 显示安装实例
--layout <value> : 选择安装模板(安装必选参数).
模板选择：
- default: (FHS compliant),
- /usr,
- /usr/local,
- oldschool: 之前版本安装路径,
- custom: 自定义安装路径,
- RPM: for building RPM's. Requires $RPM_BUILD_ROOT.
- DEB: for building DEB's. Requires $DEB_BUILD_ROOT.
--striproot : Strip path from custom layout (for package maintainers).
--install : 根据选择目录安装
--show : 显示安装路径
--remove : 卸载rkhunter
--version : 显示安装版本
我使用的安装指令
#./installer.sh --layout default --install
2.2 rkhunter操作
#/usr/local/bin/rkhunter --propupd
#/usr/local/bin/rkhunter -c --sk -rwo
Warning: File '/bin/awk' has the immutable-bit set.
Warning: File '/bin/basename' has the immutable-bit set.
Warning: File '/bin/bash' has the immutable-bit set.
Warning: File '/bin/cat' has the immutable-bit set.
Warning: File '/bin/chmod' has the immutable-bit set.
Warning: File '/bin/chown' has the immutable-bit set.
Warning: File '/bin/cp' has the immutable-bit set.
Warning: File '/bin/csh' has the immutable-bit set.
Warning: File '/bin/cut' has the immutable-bit set.
Warning: File '/bin/date' has the immutable-bit set.
Warning: File '/bin/df' has the immutable-bit set.
Warning: File '/bin/dmesg' has the immutable-bit set.
Warning: File '/bin/echo' has the immutable-bit set.
Warning: File '/bin/ed' has the immutable-bit set.
Warning: File '/bin/egrep' has the immutable-bit set.
Warning: File '/bin/env' has the immutable-bit set.
Warning: File '/bin/fgrep' has the immutable-bit set.
Warning: File '/bin/grep' has the immutable-bit set.
Warning: File '/bin/kill' has the immutable-bit set.
Warning: File '/bin/login' has the immutable-bit set.
Warning: File '/bin/ls' has the immutable-bit set.
Warning: File '/bin/mail' has the immutable-bit set.
Warning: File '/bin/mktemp' has the immutable-bit set.
Warning: File '/bin/more' has the immutable-bit set.
Warning: File '/bin/mount' has the immutable-bit set.
Warning: File '/bin/mv' has the immutable-bit set.
Warning: File '/bin/netstat' has the immutable-bit set.
Warning: File '/bin/ps' has the immutable-bit set.
Warning: File '/bin/pwd' has the immutable-bit set.
Warning: File '/bin/rpm' has the immutable-bit set.
Warning: File '/bin/sed' has the immutable-bit set.
Warning: File '/bin/sh' has the immutable-bit set.
Warning: File '/bin/sort' has the immutable-bit set.
Warning: File '/bin/su' has the immutable-bit set.
Warning: File '/bin/touch' has the immutable-bit set.
Warning: File '/bin/uname' has the immutable-bit set.
Warning: File '/bin/gawk' has the immutable-bit set.
Warning: File '/bin/tcsh' has the immutable-bit set.
Warning: File '/usr/bin/awk' has the immutable-bit set.
Warning: File '/usr/bin/cut' has the immutable-bit set.
Warning: File '/usr/bin/env' has the immutable-bit set.
Warning: The command '/usr/bin/GET' has been replaced by a script: /usr/bin/GET: perl script text executable
Warning: The command '/usr/bin/groups' has been replaced by a script: /usr/bin/groups: Bourne shell script text executable
Warning: File '/usr/bin/kill' has the immutable-bit set.
Warning: The command '/usr/bin/ldd' has been replaced by a script: /usr/bin/ldd: Bourne shell script text executable
Warning: File '/usr/bin/top' has the immutable-bit set.
Warning: The command '/usr/bin/whatis' has been replaced by a script: /usr/bin/whatis: Bourne shell script text executable
Warning: File '/usr/bin/gawk' has the immutable-bit set.
Warning: File '/sbin/chkconfig' has the immutable-bit set.
Warning: File '/sbin/depmod' has the immutable-bit set.
Warning: File '/sbin/fuser' has the immutable-bit set.
Warning: File '/sbin/ifconfig' has the immutable-bit set.
Warning: File '/sbin/ifdown' has the immutable-bit set.
Warning: The command '/sbin/ifdown' has been replaced by a script: /sbin/ifdown: Bourne-Again shell script text executable
Warning: File '/sbin/ifup' has the immutable-bit set.
Warning: The command '/sbin/ifup' has been replaced by a script: /sbin/ifup: Bourne-Again shell script text executable
Warning: File '/sbin/init' has the immutable-bit set.
Warning: File '/sbin/insmod' has the immutable-bit set.
Warning: File '/sbin/ip' has the immutable-bit set.
Warning: File '/sbin/lsmod' has the immutable-bit set.
Warning: File '/sbin/modinfo' has the immutable-bit set.
Warning: File '/sbin/modprobe' has the immutable-bit set.
Warning: File '/sbin/nologin' has the immutable-bit set.
Warning: File '/sbin/rmmod' has the immutable-bit set.
Warning: File '/sbin/runlevel' has the immutable-bit set.
Warning: File '/sbin/sulogin' has the immutable-bit set.
Warning: File '/sbin/sysctl' has the immutable-bit set.
Warning: File '/sbin/syslogd' has the immutable-bit set.
Warning: File '/usr/sbin/adduser' has the immutable-bit set.
Warning: No hash value found for file '/usr/sbin/amd' in the rkhunter.dat file.
Warning: File '/usr/sbin/amd' has the immutable-bit set.
Warning: File '/usr/sbin/chroot' has the immutable-bit set.
Warning: File '/usr/sbin/groupadd' has the immutable-bit set.
Warning: File '/usr/sbin/groupdel' has the immutable-bit set.
Warning: File '/usr/sbin/groupmod' has the immutable-bit set.
Warning: File '/usr/sbin/grpck' has the immutable-bit set.
Warning: File '/usr/sbin/kudzu' has the immutable-bit set.
Warning: File '/usr/sbin/lsof' has the immutable-bit set.
Warning: File '/usr/sbin/prelink' has the immutable-bit set.
Warning: File '/usr/sbin/pwck' has the immutable-bit set.
Warning: File '/usr/sbin/sestatus' has the immutable-bit set.
Warning: File '/usr/sbin/tcpd' has the immutable-bit set.
Warning: File '/usr/sbin/useradd' has the immutable-bit set.
Warning: File '/usr/sbin/userdel' has the immutable-bit set.
Warning: File '/usr/sbin/usermod' has the immutable-bit set.
Warning: File '/usr/sbin/vipw' has the immutable-bit set.
Warning: File '/usr/sbin/xinetd' has the immutable-bit set.
Warning: Dreams Rootkit [ Warning ]
File '/usr/bin/sense' found
File '/usr/bin/sl2' found
File '/usr/bin/(swapd)' found
Warning: Checking for possible rootkit strings [ Warning ]
Found string '/dev/ttyoa' in file '/bin/netstat'. Possible rootkit: Sin Rootkit
Warning: Found possible sniffer log file: /usr/lib/libice.log
Warning: Found enabled xinetd service: /etc/xinetd.d/auth
Warning: Found enabled xinetd service: /etc/xinetd.d/cups-lpd
Warning: Found enabled xinetd service: /etc/xinetd.d/swat
Warning: Found enabled xinetd service: /etc/xinetd.d/vmware-authd
Warning: Possible promiscuous interfaces:
'ifconfig' command output:
'ip' command output: eth0
Warning: Account 'test' is root equivalent (UID = 0)
Warning: Account 'james' is root equivalent (UID = 0)
Warning: Account 'master' is root equivalent (UID = 0)
Warning: Account 'admin' is root equivalent (UID = 0)
Warning: The SSH configuration option 'PermitRootLogin' has not been set.
The default value may be 'yes', to allow root access.
Warning: The SSH configuration option 'Protocol' has not been set.
The default value may be '2,1', to allow the use of protocol version 1.
Warning: Hidden file found: /usr/share/man/man1/..1.gz: gzip compressed data, from Unix, max compression
Warning: Application 'exim', version '4.43', is out of date, and possibly a security risk.
Warning: Application 'gpg', version '1.2.6', is out of date, and possibly a security risk.
Warning: Application 'openssl', version '0.9.7a', is out of date, and possibly a security risk.
Warning: Application 'php', version '4.3.9', is out of date, and possibly a security risk.
One or more warnings have been found while checking the system.
Please check the log file (/var/log/rkhunter.log)
结果就是“中招”，基本上就是重新安装系统的命了。不过从检查的结果来看，可以判断所中的rootkit的类型和被替换的系统文件。同时对一些程序版本进行检测，提供的信息比较多。
2.3 指令参数说明
#/usr/local/bin/rkhunter
Usage: rkhunter {--check | --update | --versioncheck |
--propupd [{filename | directory | package name},...] |
--list [{tests | {lang | languages} | rootkits},...] |
--version | --help} [options]
Current options are:
--append-log 在日志文件后追加日志，而不覆盖原有日志
--bindir <directory>... Use the specified command directories
-c, --check 检测当前系统
--cs2, --color-set2 Use the second color set for output
--configfile <file> 使用特定的配置文件
--cronjob 作为cron定期运行
(包含参数 -c, --sk , --nocolors )
--dbdir <directory> Use the specified database directory
--debug Debug模式(不要使用除非要求使用)
--disable <test>[,<test>...] 跳过指定检查对象(默认为无)
--display-logfile 在最后显示日志文件内容
--enable <test>[,<test>...] 对指定检测对象进行检查
(默认检测所有对象)
--hash {MD5 | SHA1 | NONE | 使用指定的文件哈希函数
<command>} (Default is SHA1)
-h, --help 显示帮助菜单
--lang, --language <language> 指定使用的语言
(Default is English)
--list [tests | languages | 罗列测试对象明朝，使用语言，可检测的木马程序
rootkits]
-l, --logfile [file] 写到指定的日志文件名
(Default is /var/log/rkhunter.log)
--noappend-log 不追加日志，直接覆盖日志文件
--nocolors 输出只显示黑白两色
--nolog 不写入日志文件
--nomow, --no-mail-on-warning 如果有警告信息，不发送邮件
--ns, --nosummary 不显示检查结果的统计数据
--novl, --no-verbose-logging 不显示详细记录
--pkgmgr {RPM | DPKG | BSD | 使用特定的包管理用于文件的哈希值验证
NONE} (Default is NONE)
--propupd [file | directory | 更新整个文件属性数据库或仅仅更新指定条目
package]...
-q, --quiet 安静模式(no output at all)
--rwo, --report-warnings-only 只显示警告信息
-r, --rootdir <directory> 使用指定的root目录
--sk, --skip-keypress 自动完成所有检测，跳过键盘输入
--summary 显示检测结果的统计信息
(This is the default)
--syslog [facility.priority] 记录检测启动和结束时间到系统日志中
(Default level is authpriv.notice)
--tmpdir <directory> 使用指定的临时目录
--update 检测更新内容
--vl, --verbose-logging 使用详细日志记录 (on by default)
-V, --version 显示版本信息
--versioncheck 检测最新版本
-x, --autox 当X在使用时，自动启动检测
-X, --no-autox 当X在使用时，不自启检测
本文所述Chkrootkit命令安装方法已由VPS管理百科验证通过
rootkit从浅显的层面来讲即一种具有自我隐蔽性的后门程序，它往往被入侵者作为一种入侵工具。通过rootkit，入侵者可以偷偷控制被入侵的电脑，因此危害巨大。chkrootkit是一个Linux系统下的查找检测rootkit后门的工具。本文将介绍chkrootkit的安装与使用方法。
chkrootkit没有包含在官方的CentOS或Debian源，因此我们将采取手动编译的方法来安装，这种方式也更加安全。由于需要编译源代码，因此还需要在系统中安装好gcc编译包。
安装方法
1、准备gcc编译环境
对于CentOS系统，执行下述三条命令：
yum -y install gcc
yum -y install gcc-c++
yum -y install make
对于debian系统，执行下述两条命令：
apt-get -y install gcc
apt-get -y install make
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3、解压下载回来的安装包
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4、编译安装（后文命令中出现的“*”无需替换成具体字符，原样复制执行即可）
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注意，上面的编译命令为make sense。
5、把编译好的文件部署到/usr/local/目录中，并删除遗留的文件
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至此，安装完毕。
使用方法
安装好的chkrootkit程序位于 /usr/local/chkrootkit/chkrootkit
直接执行
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安全提示：由于chkrootkit的检查过程使用了部分系统命令。因此，如果服务器被入侵，则依赖的系统命令可能也已经被入侵者做了手脚，chkrootkit的结果将变得完全不可信，甚至连系统ls等查看文件的基础命令也变得不可信。
