Tripwireの導入

2013/5/30

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• Tripwireとは？ Tripwireはホスト型IDSである。IDS（Intrusion Detection System）とは侵入を検知するシステムである。Tripwireはホストのファイルの改竄を監視してくれる。

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• TripwireをEPELからインストール

  # yum --enablerepo=epel -y install tripwire
  

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• Tripwireの設定

  # tripwire-setup-keyfiles
  

Enter the site keyfile passphrase:
# 任意のパスフレーズ
Verify the site keyfile passphrase:
# 再入力
Enter the local keyfile passphrase:
# 任意のパスフレーズを設定
Verify the local keyfile passphrase:
# 再入力
Please enter your site passphrase:
# パスフレーズで応答
Please enter your site passphrase:
# パスフレーズで応答

# cd /etc/tripwire
# vi twcfg.txt

# 9行目の値をtrueにする。
LOOSEDIRECTORYCHECKING = true
# 12行目：報告レベル４にする。
REPORTLEVEL = 4

• 暗号署名設定ファイル作成

  # cd /etc/tripwire
  # twadmin -m F -c tw.cfg -S site.key twcfg.txt
  

Please enter your site passphrase:
#パスフレーズ入力
Wrote configuration file: /etc/tripwire/tw.cfg

# ポリシーファイル最適化スクリプト作成

# cd /etc/tripwire
# vi twpolmake.pl

#!/usr/bin/perl
# Tripwire Policy File customize tool
# ----------------------------------------------------------------
# Copyright (C) 2003 Hiroaki Izumi
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; either version 2
# of the License, or (at your option) any later version.
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
# ----------------------------------------------------------------
# Usage:
#     perl twpolmake.pl {Pol file}
# ----------------------------------------------------------------
#
$POLFILE=$ARGV[0]; 

open(POL,"$POLFILE") or die "open error: $POLFILE" ;
my($myhost,$thost) ;
my($sharp,$tpath,$cond) ;
my($INRULE) = 0 ;  

while (<POL>) {
   chomp;
   if (($thost) = /^HOSTNAME\s*=\s*(.*)\s*;/) {
      $myhost = `hostname` ; chomp($myhost) ;
      if ($thost ne $myhost) {
         $_="HOSTNAME=\"$myhost\";" ;
      }
   }
   elsif ( /^{/ ) {
      $INRULE=1 ;
   }
   elsif ( /^}/ ) {
      $INRULE=0 ;
   }
   elsif ($INRULE == 1 and ($sharp,$tpath,$cond) = /^(\s*\#?\s*)(\/\S+)\b(\s+->\s+.+)$/) {
      $ret = ($sharp =~ s/\#//g) ;
      if ($tpath eq '/sbin/e2fsadm' ) {
         $cond =~ s/;\s+(tune2fs.*)$/; \#$1/ ;
      }
      if (! -s $tpath) {
         $_ = "$sharp#$tpath$cond" if ($ret == 0) ;
      }
      else {
         $_ = "$sharp$tpath$cond" ;
      }
   }
   print "$_\n" ;
}
close(POL) ;

# perl twpolmake.pl twpol.txt > twpol.txt.new
# twadmin -m P -c tw.cfg -p tw.pol -S site.key twpol.txt.new

Please enter your site passphrase:
# パスフレーズ入力
Wrote policy file: /etc/tripwire/tw.pol

# tripwire -m i -s -c tw.cfg
Please enter your local passphrase:
# パスフレーズ入力

• 実行してみる

  # cd /etc/tripwire
  # tripwire -m c -s -c tw.cfg
  

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