Contents
Tripwire
1.Install
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# dnf -y install tripwire |
2.Passphrase setting
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# tripwire-setup-keyfiles ---------------------------------------------- The Tripwire site and local passphrases are used to sign a variety of files, such as the configuration, policy, and database files. Passphrases should be at least 8 characters in length and contain both letters and numbers. See the Tripwire manual for more information. ---------------------------------------------- Creating key files... (When selecting a passphrase, keep in mind that good passphrases typically have upper and lower case letters, digits and punctuation marks, and are at least 8 characters in length.) Enter the site keyfile passphrase: ←Enter any "Site Passphrase" Verify the site keyfile passphrase: ←Enter "Site Passphrase" again Generating key (this may take several minutes)...Key generation complete. (When selecting a passphrase, keep in mind that good passphrases typically have upper and lower case letters, digits and punctuation marks, and are at least 8 characters in length.) Enter the local keyfile passphrase: ←Enter any "local passphrase" Verify the local keyfile passphrase: ←Enter "Local Passphrase" again Generating key (this may take several minutes)...Key generation complete. ---------------------------------------------- Signing configuration file... Please enter your site passphrase: ←Enter "Site Passphrase" Wrote configuration file: /etc/tripwire/tw.cfg A clear-text version of the Tripwire configuration file: /etc/tripwire/twcfg.txt has been preserved for your inspection. It is recommended that you move this file to a secure location and/or encrypt it in place (using a tool such as GPG, for example) after you have examined it. ---------------------------------------------- Signing policy file... Please enter your site passphrase: ←Enter "Site Passphrase" Wrote policy file: /etc/tripwire/tw.pol A clear-text version of the Tripwire policy file: /etc/tripwire/twpol.txt has been preserved for your inspection. This implements a minimal policy, intended only to test essential Tripwire functionality. You should edit the policy file to describe your system, and then use twadmin to generate a new signed copy of the Tripwire policy. Once you have a satisfactory Tripwire policy file, you should move the clear-text version to a secure location and/or encrypt it in place (using a tool such as GPG, for example). Now run "tripwire --init" to enter Database Initialization Mode. This reads the policy file, generates a database based on its contents, and then cryptographically signs the resulting database. Options can be entered on the command line to specify which policy, configuration, and key files are used to create the database. The filename for the database can be specified as well. If no options are specified, the default values from the current configuration file are used. |
3.Tripwire Configuration
①Configuration File Edit
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# vi /etc/tripwire/twcfg.txt ●Per line 9 Add "#" at the beginning of the line and "LOOSEDIRECTORYCHECKING =true" on the line below it ●Per line 12 Add "#" at the beginning of the line and "REPORTLEVEL =4" on the line below it. Level 4 provides the most detailed report of the five levels from "0" to "4". #REPORTLEVEL =3 REPORTLEVEL =4 |
②Create a Tripwire configuration file (cryptographically signed version)
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# twadmin -m F -c /etc/tripwire/tw.cfg -S /etc/tripwire/site.key /etc/tripwire/twcfg.txt Please enter your site passphrase: ←Enter site passphrase" Wrote configuration file: /etc/tripwire/tw.cfg |
③Delete Tripwire configuration file (text version)
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# rm -f /etc/tripwire/twcfg.txt |
④Policy File Settings
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# cd /etc/tripwire/ # vi twpolmake.pl |
Contents of twpolmake.pl
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#!/usr/bin/perl # Tripwire Policy File customize tool # $POLFILE=$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) ; |
⑤Policy File Optimizations
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# perl /etc/tripwire/twpolmake.pl /etc/tripwire/twpol.txt > /etc/tripwire/twpol.txt.new |
⑥Create policy file (cryptographically signed version) based on optimized policy file
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# twadmin -m P -c /etc/tripwire/tw.cfg -p /etc/tripwire/tw.pol -S /etc/tripwire/site.key /etc/tripwire/twpol.txt.new Please enter your site passphrase: ←Enter local passphrase Wrote policy file: /etc/tripwire/tw.pol |
⑦Create database and check operation
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# tripwire -m i -s -c /etc/tripwire/tw.cfg Please enter your local passphrase: ←Enter local passphrase |
Create test files
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# echo test > /root/test.txt |
Check Tripwire operation
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# tripwire -m c -s -c /etc/tripwire/tw.cfg OK if it appears as follows Open Source Tripwire(R) 2.4.3.7 Integrity Check Report Report generated by: root Report created on: Sun 28 Apr 2024 10:45:00 AM JST Database last updated on: Never =============================================================================== Report Summary: =============================================================================== Host name: Lepard Host IP address: 192.168.11.83 Host ID: None Policy file used: /etc/tripwire/tw.pol Configuration file used: /etc/tripwire/tw.cfg Database file used: /var/lib/tripwire/Lepard.twd Command line used: tripwire -m c -s -c /etc/tripwire/tw.cfg =============================================================================== Rule Summary: =============================================================================== ------------------------------------------------------------------------------- Section: Unix File System ------------------------------------------------------------------------------- Rule Name Severity Level Added Removed Modified --------- -------------- ----- ------- -------- User binaries 66 0 0 0 Tripwire Binaries 100 0 0 0 Libraries 66 0 0 0 Operating System Utilities 100 0 0 0 File System and Disk Administraton Programs 100 0 0 0 Kernel Administration Programs 100 0 0 0 Networking Programs 100 0 0 0 System Administration Programs 100 0 0 0 Hardware and Device Control Programs 100 0 0 0 System Information Programs 100 0 0 0 (/sbin/runlevel) Application Information Programs 100 0 0 0 (/sbin/rtmon) Critical Utility Sym-Links 100 0 0 0 Shell Binaries 100 0 0 0 Critical system boot files 100 0 0 0 * Tripwire Data Files 100 1 0 0 System boot changes 100 0 0 0 OS executables and libraries 100 0 0 0 Security Control 100 0 0 0 Login Scripts 100 0 0 0 Critical configuration files 100 0 0 0 * Root config files 100 1 0 0 Invariant Directories 66 0 0 0 Temporary directories 33 0 0 0 Critical devices 100 0 0 0 Total objects scanned: 75585 Total violations found: 2 =============================================================================== Object Summary: =============================================================================== ------------------------------------------------------------------------------- # Section: Unix File System ------------------------------------------------------------------------------- ------------------------------------------------------------------------------- Rule Name: Tripwire Data Files (/var/lib/tripwire) Severity Level: 100 ------------------------------------------------------------------------------- Added: "/var/lib/tripwire/Lepard.twd" ------------------------------------------------------------------------------- Rule Name: Root config files (/root) Severity Level: 100 ------------------------------------------------------------------------------- Added: "/root/test.txt" =============================================================================== Error Report: =============================================================================== No Errors ------------------------------------------------------------------------------- *** End of report *** Open Source Tripwire 2.4 Portions copyright 2000-2018 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. |
Delete test files
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# rm -f /root/test.txt |
⑧Tripwire Scheduled Scripts
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# cd /var/www/system # vi tripwire.sh |
Contents of tripwire.sh
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#!/bin/bash PATH=/usr/sbin:/usr/bin:/bin:/usr/local/tripwire/sbin # Passphrase setting LOCALPASS=xxxxx # local passphrase SITEPASS=xxxxx # site passphrase #Specify e-mail address for notification MAIL="[your mailaddress]" cd /etc/tripwire # Tripwire check run tripwire -m c -s -c tw.cfg|mail -s "Tripwire(R) Integrity Check Report in `hostname`" $MAIL # Policy File Update twadmin -m p -c tw.cfg -p tw.pol -S site.key > twpol.txt perl twpolmake.pl twpol.txt > twpol.txt.new twadmin -m P -c tw.cfg -p tw.pol -S site.key -Q $SITEPASS twpol.txt.new > /dev/null rm -f twpol.txt* *.bak # Database update rm -f /usr/local/tripwire/lib/tripwire/*.twd* tripwire -m i -s -c tw.cfg -P $LOCALPASS |
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# chmod 700 tripwire.sh Add to cron # crontab -e 0 3 * * * /var/www/system/tripwire.sh |
Confirmation that the results of the tripwire execution are notified to the specified e-mail address
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# /var/www/system/tripwire.sh |
Logwatch
①Install
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# dnf install logwatch |
②Edit configuration file
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# cat /usr/share/logwatch/default.conf/logwatch.conf >> /etc/logwatch/conf/logwatch.conf # vi /etc/logwatch/conf/logwatch.conf ●Lene 76 : Set "MailTo = root" as a comment and set the email address you want to receive notifications to the line below it. #MailTo = root MailTo = [Mail address] ●Per Line 115 : Set the level of detail for log notifications #Detail = Low Detail = High |
③Output Logwatch reports
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# logwatch --output stdout |
It will appear as follows
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################### Logwatch 7.10 (01/22/24) #################### Processing Initiated: Sun Apr 28 11:01:38 2024 Date Range Processed: today ( 2024-Apr-28 ) Period is day. Detail Level of Output: 10 Type of Output/Format: stdout / text Logfiles for Host: Lepard ################################################################## --------------------- Kernel Audit Begin ------------------------ *** Denials *** system_u:system_r:init_t:s0 system_u:object_r:root_t:s0 (rmdir dir): 2 times system_u:system_r:systemd_hwdb_t:s0 system_u:system_r:systemd_hwdb_t:s0 (dac_override capability): 1 times Number of audit daemon starts: 3 Number of audit daemon stops: 3 Number of audit initializations: 3 -----------Omission---------- **Unmatched Entries** No hostname configured, using default hostname.: 2 Time(s) Reexecuting requested from client PID 2099 ('systemctl') (unit session-5.scope)...: 1 Time(s) Relabeled /dev, /dev/shm, /run, /sys/fs/cgroup in 26.739ms.: 1 Time(s) Reloading...: 15 Time(s) Running in initrd.: 3 Time(s) ---------------------- Systemd End ------------------------- --------------------- Disk Space Begin ------------------------ Filesystem Size Used Avail Use% Mounted on /dev/mapper/fedora-root 15G 4.3G 11G 29% / /dev/nvme0n1p2 960M 286M 675M 30% /boot ---------------------- Disk Space End ------------------------- ###################### Logwatch End ######################### |
④Test to see if the report arrives at the address you set. Check if you receive a log report email like the one above.
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# /etc/cron.daily/0logwatch |
Introduce disk usage check script
1. Script Creation
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# cd /var/www/system # vi disk_capacity_check.sh |
Contents of disk_capacity_check.sh
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#!/bin/bash #Designation of e-mail address to be notified MAIL="[Mail address]" DVAL=`/bin/df / | /usr/bin/tail -1 | /bin/sed 's/^.* \([0-9]*\)%.*$/\1/'` if [ $DVAL -gt 80 ]; then echo "Disk usage alert: $DVAL %" | mail -s "Disk Space Alert in `hostname`" $MAIL fi |
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# chmod 700 disk_capacity_check.sh |
2. Execution Confirmation
①Check current usage rates
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# df -h |
It appears as follows
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Filesystem Size Used Avail Use% Mounted on /dev/mapper/fedora-root 15G 5.4G 9.6G 36% / devtmpfs 4.0M 0 4.0M 0% /dev tmpfs 1.9G 0 1.9G 0% /dev/shm efivarfs 256K 55K 197K 22% /sys/firmware/efi/efivars tmpfs 775M 1.6M 774M 1% /run /dev/loop1 39M 39M 0 100% /var/lib/snapd/snap/snapd/21465 /dev/loop0 46M 46M 0 100% /var/lib/snapd/snap/certbot/3700 /dev/loop2 64M 64M 0 100% /var/lib/snapd/snap/core20/2264 tmpfs 1.9G 0 1.9G 0% /tmp /dev/nvme0n1p2 960M 339M 622M 36% /boot /dev/nvme0n1p1 599M 7.5M 592M 2% /boot/efi tmpfs 388M 8.0K 388M 1% /run/user/1000 |
②Create a dummy file to achieve at least 80% utilization(In the example, the name is dummyfile and it is about 8G.)
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# dd if=/dev/zero of=dummyfile bs=1M count=8000 |
➂Run check scripts
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# /var/www/system/disk_capacity_check.sh |
You will receive an email to the email address you have set up, stating something like "Disk usage alert: 89%".
④Delete "dummyfile"
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# rm dummyfile |
⑤Periodic Execution Setting
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# crontab -e 30 2 * * * /var/www/system/disk_capacity_check.sh |