本文是一篇关于 Debian 中安装和配置 tripewire 的文章。它是 Linux 环境下基于主机的入侵检测系统（IDS）。tripwire 的高级功能可以检测并报告任何 Linux 中未授权的（文件和目录）的更改。tripewire 安装之后，会先创建一个基本的数据库，tripewire 监控并检测新文件的创建修改和谁修改了它等等。如果修改是合法的，你可以接受修改并更新 tripwire 的数据库。
安装和配置
tripwire 在 Debian VM 中的安装如下。
# apt-get install tripwire
安装中，tripwire 会有下面的配置提示。
站点密钥创建
tripwire 需要一个站点口令（site passphrase）来加密 tripwire 的配置文件 tw.cfg 和策略文件 tw.pol。tripewire 使用指定的密码加密两个文件。一个 tripewire 实例必须指定站点口令。
本地密钥口令
本地口令用来保护 tripwire 数据库和报告文件。本地密钥用于阻止非授权的 tripewire 数据库修改。
tripwire 配置路径
tripewire 配置存储在 /etc/tripwire/twcfg.txt。它用于生成加密的配置文件 tw.cfg。
tripwire 策略路径
tripwire 在 /etc/tripwire/twpol.txt 中保存策略文件。它用于生成加密的策略文件 tw.pol。
安装完成后如下图所示。
tripwire 配置文件 (twcfg.txt)
tripewire 配置文件（twcfg.txt）细节如下图所示。加密策略文件（tw.pol）、站点密钥（site.key）和本地密钥（hostname-local.key）在后面展示。
ROOT =/usr/sbin
POLFILE =/etc/tripwire/tw.pol
DBFILE =/var/lib/tripwire/$(HOSTNAME).twd
REPORTFILE =/var/lib/tripwire/report/$(HOSTNAME)-$(DATE).twr
SITEKEYFILE =/etc/tripwire/site.key
LOCALKEYFILE =/etc/tripwire/$(HOSTNAME)-local.key
EDITOR =/usr/bin/editor
LATEPROMPTING =false
LOOSEDIRECTORYCHECKING =false
MAILNOVIOLATIONS =true
EMAILREPORTLEVEL =3
REPORTLEVEL =3
SYSLOGREPORTING =true
MAILMETHOD =SMTP
SMTPHOST =localhost
SMTPPORT =25
TEMPDIRECTORY =/tmp
tripwire 策略配置
在生成基础数据库之前先配置 tripwire 配置。有必要经用一些策略如 /dev、 /proc 、/root/mail 等。详细的 twpol.txt 策略文件如下所示。
@@section GLOBAL
TWBIN = /usr/sbin;
TWETC = /etc/tripwire;
TWVAR = /var/lib/tripwire;
#
# File System Definitions
#
@@section FS
#
# First, some variables to make configuration easier
#
SEC_CRIT = $(IgnoreNone)-SHa ; # Critical files that cannot change
SEC_BIN = $(ReadOnly) ; # Binaries that should not change
SEC_CONFIG = $(Dynamic) ; # Config files that are changed
# infrequently but accessed
# often
SEC_LOG = $(Growing) ; # Files that grow, but that
# should never change ownership
SEC_INVARIANT = +tpug ; # Directories that should never
# change permission or ownership
SIG_LOW = 33 ; # Non-critical files that are of
# minimal security impact
SIG_MED = 66 ; # Non-critical files that are of
# significant security impact
SIG_HI = 100 ; # Critical files that are
# significant points of
# vulnerability
#
# tripwire Binaries
#
(
rulename = "tripwire Binaries",
severity = $(SIG_HI)
)
{
$(TWBIN)/siggen -> $(SEC_BIN) ;
$(TWBIN)/tripwire -> $(SEC_BIN) ;
$(TWBIN)/twadmin -> $(SEC_BIN) ;
$(TWBIN)/twprint -> $(SEC_BIN) ;
}
{
/boot -> $(SEC_CRIT) ;
/lib/modules -> $(SEC_CRIT) ;
}
(
rulename = "Boot Scripts",
severity = $(SIG_HI)
)
{
/etc/init.d -> $(SEC_BIN) ;
#/etc/rc.boot -> $(SEC_BIN) ;
/etc/rcS.d -> $(SEC_BIN) ;
/etc/rc0.d -> $(SEC_BIN) ;
/etc/rc1.d -> $(SEC_BIN) ;
/etc/rc2.d -> $(SEC_BIN) ;
/etc/rc3.d -> $(SEC_BIN) ;
/etc/rc4.d -> $(SEC_BIN) ;
/etc/rc5.d -> $(SEC_BIN) ;
/etc/rc6.d -> $(SEC_BIN) ;
}
(
rulename = "Root file-system executables",
severity = $(SIG_HI)
)
{
/bin -> $(SEC_BIN) ;
/sbin -> $(SEC_BIN) ;
}
#
# Critical Libraries
#
(
rulename = "Root file-system libraries",
severity = $(SIG_HI)
)
{
/lib -> $(SEC_BIN) ;
}
#
# Login and Privilege Raising Programs
#
(
rulename = "Security Control",
severity = $(SIG_MED)
)
{
/etc/passwd -> $(SEC_CONFIG) ;
/etc/shadow -> $(SEC_CONFIG) ;
}
{
#/var/lock -> $(SEC_CONFIG) ;
#/var/run -> $(SEC_CONFIG) ; # daemon PIDs
/var/log -> $(SEC_CONFIG) ;
}
# These files change the behavior of the root account
(
rulename = "Root config files",
severity = 100
)
{
/root -> $(SEC_CRIT) ; # Catch all additions to /root
#/root/mail -> $(SEC_CONFIG) ;
#/root/Mail -> $(SEC_CONFIG) ;
/root/.xsession-errors -> $(SEC_CONFIG) ;
#/root/.xauth -> $(SEC_CONFIG) ;
#/root/.tcshrc -> $(SEC_CONFIG) ;
#/root/.sawfish -> $(SEC_CONFIG) ;
#/root/.pinerc -> $(SEC_CONFIG) ;
#/root/.mc -> $(SEC_CONFIG) ;
#/root/.gnome_private -> $(SEC_CONFIG) ;
#/root/.gnome-desktop -> $(SEC_CONFIG) ;
#/root/.gnome -> $(SEC_CONFIG) ;
#/root/.esd_auth -> $(SEC_CONFIG) ;
# /root/.elm -> $(SEC_CONFIG) ;
#/root/.cshrc -> $(SEC_CONFIG) ;
#/root/.bashrc -> $(SEC_CONFIG) ;
#/root/.bash_profile -> $(SEC_CONFIG) ;
# /root/.bash_logout -> $(SEC_CONFIG) ;
#/root/.bash_history -> $(SEC_CONFIG) ;
#/root/.amandahosts -> $(SEC_CONFIG) ;
#/root/.addressbook.lu -> $(SEC_CONFIG) ;
#/root/.addressbook -> $(SEC_CONFIG) ;
#/root/.Xresources -> $(SEC_CONFIG) ;
#/root/.Xauthority -> $(SEC_CONFIG) -i ; # Changes Inode number on login
/root/.ICEauthority -> $(SEC_CONFIG) ;
}
#
# Critical devices
#
(
rulename = "Devices & Kernel information",
severity = $(SIG_HI),
)
{
#/dev -> $(Device) ;
#/proc -> $(Device) ;
}
tripwire 报告
tripwire-check 命令检查 twpol.txt 文件并基于此文件生成 tripwire 报告如下。如果 twpol.txt 中有任何错误，tripwire 不会生成报告。
文本形式报告
root@VMdebian:/home/labadmin# tripwire --check
Parsing policy file: /etc/tripwire/tw.pol
*** Processing Unix File System ***
Performing integrity check...
Wrote report file: /var/lib/tripwire/report/VMdebian-20151024-122322.twr
Open Source tripwire(R) 2.4.2.2 Integrity Check Report
Report generated by: root
Report created on: Sat Oct 24 12:23:22 2015
Database last updated on: Never
Report Summary:
=========================================================
Host name: VMdebian
Host IP address: 127.0.1.1
Host ID: None
Policy file used: /etc/tripwire/tw.pol
Configuration file used: /etc/tripwire/tw.cfg
Database file used: /var/lib/tripwire/VMdebian.twd
Command line used: tripwire --check
=========================================================
Rule Summary:
=========================================================
-------------------------------------------------------------------------------
Section: Unix File System
-------------------------------------------------------------------------------
Rule Name Severity Level Added Removed Modified
--------- -------------- ----- ------- --------
Other binaries 66 0 0 0
tripwire Binaries 100 0 0 0
Other libraries 66 0 0 0
Root file-system executables 100 0 0 0
tripwire Data Files 100 0 0 0
System boot changes 100 0 0 0
(/var/log)
Root file-system libraries 100 0 0 0
(/lib)
Critical system boot files 100 0 0 0
Other configuration files 66 0 0 0
(/etc)
Boot Scripts 100 0 0 0
Security Control 66 0 0 0
Root config files 100 0 0 0
Invariant Directories 66 0 0 0
Total objects scanned: 25943
Total violations found: 0
=========================Object Summary:================================
-------------------------------------------------------------------------------
# Section: Unix File System
-------------------------------------------------------------------------------
No violations.
===========================Error Report:=====================================
No Errors
-------------------------------------------------------------------------------
*** End of report ***
Open Source tripwire 2.4 Portions copyright 2000 tripwire, Inc. tripwire is a registered
trademark of tripwire, Inc. This software comes with ABSOLUTELY NO WARRANTY;
for details use --version. This is free software which may be redistributed
or modified only under certain conditions; see COPYING for details.
All rights reserved.
Integrity check complete.
总结
本篇中，我们学习安装配置开源入侵检测软件 tripwire。首先生成基础数据库并通过比较检测出任何改动（文件/文件夹）。然而，tripwire 并不是实时监测的 IDS。
via: http://linoxide.com/security/configure-tripwire-ids-debian/
作者：nido 译者：geekpi 校对：wxy
本文由 LCTT 原创编译，Linux中国 荣誉推出
