Contents
Tripwire
1.Install
|
1 2 3 4 5 |
# dnf -y install tripwire Installed: tripwire-2.4.3.7-20.el10_2.x86_64 Complete! |
2. Passphrase setting
Set site passphrase and local passphrase
|
1 |
# 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: [site pass]
Verify the site keyfile passphrase: [site pass]
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: [local pass]
Verify the local keyfile passphrase: [local pass]
Generating key (this may take several minutes)…Key generation complete.
------------------------------------------------
Signing configuration file…
Please enter your site passphrase: [site pass]
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: [site pass]
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
① Configuration File Edit
|
1 2 3 4 5 6 7 |
# vi /etc/tripwire/twcfg.txt Line 9 Change to "LOOSEDIRECTORYCHECKING =true" Line 12 : change REPORTLEVEL =4 |
② Create a Tripwire configuration file (cryptographically signed version)
|
1 2 3 |
# twadmin -m F -c /etc/tripwire/tw.cfg -S /etc/tripwire/site.key /etc/tripwire/twcfg.txt Please enter your site passphrase: ←site pass Wrote configuration file: /etc/tripwire/tw.cfg |
③ Delete Tripwire configuration file (text version)
|
1 |
# rm -f /etc/tripwire/twcfg.txt |
④ Policy File Settings
|
1 2 |
# cd /etc/tripwire/ # vi twpolmake.pl |
Contents of twpolmake.pl
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 |
#!/usr/bin/perl # $POLFILE=$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) ; |
⑤ Policy File Optimizations
|
1 |
# perl /etc/tripwire/twpolmake.pl /etc/tripwire/twpol.txt > /etc/tripwire/twpol.txt.new |
⑥ Create policy file (cryptographically signed version) based on optimized policy file
|
1 2 |
# 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: ←site pass |
⑦ Create database and check operation
|
1 2 |
# tripwire -m i -s -c /etc/tripwire/tw.cfg Please enter your local passphrase: ←local pass |
Create test files
|
1 |
# echo test > /root/test.txt |
Check Tripwire operation
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 |
# tripwire -m c -s -c /etc/tripwire/tw.cfg If it displays as shown below, it's OK. Open Source Tripwire(R) 2.4.3.7 Integrity Check Report Report generated by: root Report created on: Thu 11 Dec 2025 09:42:53 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: 67033 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
|
1 |
# rm -f /root/test.txt |
⑧ Creating a Tripwire Script for Reporting Results via Email
|
1 2 |
# cd /var/www/system # vi tripwire.sh |
Contents of tripwire.sh
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 |
#!/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 |
|
1 2 3 4 5 |
# 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
|
1 |
# /var/www/system/tripwire.sh |
Chkrootkit
Install a rootkit detection tool called chkrootkit to check whether a rootkit has been installed on the Linux server.
Since chkrootkit is checked using the following command, it is desirable to install it in the early stages after Linux installation, since it is useless after the command itself has been tampered with so that rootkit cannot be detected.
[Commands used by chkrootkit]
awk, cut, echo, egrep, find, head, id, ls, netstat, ps, strings, sed, uname
Note that chkrootkit can only detect known rootkits and cannot detect new rootkits.
①Download and install chkrootkit
|
1 2 3 |
# cd /usr/local/src # wget https://launchpad.net/chkrootkit/main/0.55/+download/chkrootkit-0.55.tar.gz # tar xvf chkrootkit-0.55.tar.gz |
➁Create /root/bin directory and move chkrootkit command to that directory
|
1 2 |
# mkdir -p /root/bin # mv chkrootkit-0.55/chkrootkit /root/bin |
➂Check chkrootkit.
|
1 2 |
# chkrootkit | grep INFECTED If nothing is displayed, there is no problem. |
If the following error occurs
egrep: warning: egrep is obsolescent; using grep -E
|
1 2 3 |
# mv /usr/bin/egrep /usr/bin/egrep.backup # echo 'grep -E $@' > /usr/bin/egrep # chmod a+x /usr/bin/egrep |
④Create chkrootkit periodic execution script and change permissions
Create chkrootkit execution script in a directory where it is automatically executed daily
|
1 |
# vi /etc/cron.daily/chkrootkit |
Scheduled Script Contents
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 |
#!/bin/bash PATH=/usr/bin:/bin:/root/bin LOG=/tmp/$(basename ${0}) # Run chkrootkit chkrootkit > $LOG 2>&1 # log output cat $LOG | logger -t $(basename ${0}) # SMTPS bindshell false positive response if [ ! -z "$(grep 465 $LOG)" ] && \ [ -z $(/usr/sbin/lsof -i:465|grep bindshell) ]; then sed -i '/465/d' $LOG fi # Support for Suckit false positives when updating upstart package if [ ! -z "$(grep Suckit $LOG)" ] && \ [ -z "$(rpm -V `rpm -qf /sbin/init`)" ]; then sed -i '/Suckit/d' $LOG fi # Send mail to root only when rootkit is detected [ ! -z "$(grep INFECTED $LOG)" ] && \ grep INFECTED $LOG | mail -s "chkrootkit report in `hostname`" root |
Add execution permission to chkrootkit execution script
|
1 |
# chmod 700 /etc/cron.daily/chkrootkit |
⑤Backup commands used by chkrootkit
If the commands used by chkrootkit are tampered with, rootkit will not be detected.
Back up these commands.
If necessary, run chkrootkit with the backed up command
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 |
# cd /root # mkdir /root/chkrootkit_cmd # cp `which --skip-alias awk cut echo egrep find head id ls netstat ps strings sed ssh uname` chkrootkit_cmd/ # ls -l /root/chkrootkit_cmd/ total 2616 -rwxr-xr-x 1 root root 754360 Dec 11 10:14 awk -rwxr-xr-x 1 root root 53240 Dec 11 10:14 cut -rwxr-xr-x 1 root root 36496 Dec 11 10:14 echo -rwxr-xr-x 1 root root 11 Dec 11 10:14 egrep -rwxr-xr-x 1 root root 213320 Dec 11 10:14 find -rwxr-xr-x 1 root root 45008 Dec 11 10:14 head -rwxr-xr-x 1 root root 44928 Dec 11 10:14 id -rwxr-xr-x 1 root root 141192 Dec 11 10:14 ls -rwxr-xr-x 1 root root 148672 Dec 11 10:14 netstat -rwxr-xr-x 1 root root 120584 Dec 11 10:14 ps -rwxr-xr-x 1 root root 119984 Dec 11 10:14 sed -rwxr-xr-x 1 root root 897536 Dec 11 10:14 ssh -rwxr-xr-x 1 root root 36944 Dec 11 10:14 strings -rwxr-xr-x 1 root root 36664 Dec 11 10:14 uname |
⑥Run chkrootkit on the copied command
|
1 |
# chkrootkit -p /root/chkrootkit_cmd | grep INFECTED |
If nothing is displayed, no problem.
⑦Compresses backed up commands
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 |
# tar zcvf chkrootkit_cmd.tar.gz chkrootkit_cmd chkrootkit_cmd/ chkrootkit_cmd/awk chkrootkit_cmd/cut chkrootkit_cmd/echo chkrootkit_cmd/egrep chkrootkit_cmd/find chkrootkit_cmd/head chkrootkit_cmd/id chkrootkit_cmd/ls chkrootkit_cmd/netstat chkrootkit_cmd/ps chkrootkit_cmd/strings chkrootkit_cmd/sed chkrootkit_cmd/ssh chkrootkit_cmd/uname |
|
1 2 3 4 5 6 7 8 |
# ls -l total 1812 -rw-------. 1 root root 1099 Dec 7 17:21 anaconda-ks.cfg -rw------- 1 root root 730 Dec 10 15:20 appid_stats.log drwxr-xr-x 2 root root 24 Dec 11 10:12 bin drwxr-xr-x 2 root root 172 Dec 11 10:14 chkrootkit_cmd -rw-r--r-- 1 root root 1232279 Dec 11 10:15 chkrootkit_cmd.tar.gz --------------------------------------------------------------- |
⑧Send chkrootkit use command (compressed version) to root by e-mail
|
1 |
# echo|mail -a chkrootkit_cmd.tar.gz -s chkrootkit_cmd.tar.gz root |
⑨Download and save chkrootkit_cmd.tar.gz file to Windows
⑩Delete commands on the backed up server
|
1 |
# rm -f chkrootkit_cmd.tar.gz |
Logwatch
①Install
|
1 |
# dnf -y install logwatch |
②Edit configuration file
|
1 2 3 4 5 6 7 8 9 10 11 |
# cat /usr/share/logwatch/default.conf/logwatch.conf >> /etc/logwatch/conf/logwatch.conf # vi /etc/logwatch/conf/logwatch.conf Per Line 77 : Add #MailTo = root MailTo = [Mail address] Per Line 116 : Set the level of detail for log notifications #Detail = Low Detail = High |
③Output Logwatch reports
|
1 |
# logwatch --output stdout |
It will appear as follows
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 |
################### Logwatch 7.11 (07/22/24) #################### Processing Initiated: Thu Dec 11 10:22:40 2025 Date Range Processed: yesterday ( 2025-Dec-10 ) Period is day. Detail Level of Output: 10 Type of Output/Format: stdout / text Logfiles for Host: Lepard ################################################################## --------------------- Kernel Audit Begin ------------------------ Number of audit daemon starts: 1 Number of audit initializations: 1 **Unmatched Entries** auditd[1049]: audit dispatcher initialized with q_depth=2000 and 1 active plugins: 1 Time(s) ---------------------- Kernel Audit End ------------------------- --------------------------------- --------------------------------- --------------------- Disk Space Begin ------------------------ Filesystem Size Used Avail Use% Mounted on /dev/mapper/ol-root 17G 8.2G 8.3G 50% / efivarfs 256K 81K 171K 33% /sys/firmware/efi/efivars /dev/nvme0n1p2 960M 472M 489M 50% /boot /dev/nvme0n1p1 599M 8.5M 591M 2% /boot/efi ---------------------- Disk Space End ------------------------- --------------------- lm_sensors output Begin ------------------------ nvme-pci-0b00 Adapter: PCI adapter Composite: +29.9 C ---------------------- lm_sensors output 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.
|
1 |
# /etc/cron.daily/0logwatch |
DNS Update Script
Each time the global IP changes, which happens when the network is disconnected or the router disconnects and reboots, the dynamic DNS must be accessed to inform the user that the global IP has changed.
DiCE used to do that work automatically, but since we can no longer use 32-bit software in OracleLinux10
We will create a dedicated script and run it periodically in Cron
This time we will set up DNS in Valudomain.
|
1 2 |
# cd /var/www/system # vi valuedomain.sh |
Contents of valuedomain.sh
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 |
#/bin/bash #VARIABLES DOMAINNAME="example.com" PASSWORD="password" HOSTNAME="*" ←Fill in the hostname if you want to set a specific host, or “*” if you want to target all hosts. MYIP="" # External IP Acquisition MYIP=`wget -q -O - "https://dyn.value-domain.com/cgi-bin/dyn.fcg?ip"` sleep 5 # Update process wget -q -O - "https://dyn.value-domain.com/cgi-bin/dyn.fcg?d=$DOMAINNAME&p=$PASSWORD&h=$HOSTNAME&i=$MYIP" |
|
1 |
# chmod +x valuedomain.sh |
I'll run it.
|
1 2 3 4 |
# /var/www/system/valuedomain.sh status=0 OK |
Introduce disk usage check script
1. Script Creation
|
1 2 |
# cd /var/www/system # vi disk_capacity_check.sh |
Contents of disk_capacity_check.sh
|
1 2 3 4 5 6 7 8 9 10 |
#!/bin/bash # Designation of e-mail address to be notified MAIL="<your mailaddress>" 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 |
|
1 |
# chmod 700 disk_capacity_check.sh |
2. Execution Confirmation
①Check current usage rates
|
1 |
# df -h |
It appears as follows
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 |
ilesystem Size Used Avail Use% Mounted on /dev/mapper/ol-root 17G 8.2G 8.2G 50% / devtmpfs 4.0M 0 4.0M 0% /dev tmpfs 1.7G 0 1.7G 0% /dev/shm efivarfs 256K 81K 171K 33% /sys/firmware/efi/efivars tmpfs 693M 14M 680M 2% /run tmpfs 1.0M 0 1.0M 0% /run/credentials/systemd-journald.service /dev/loop2 51M 51M 0 100% /var/lib/snapd/snap/snapd/25577 /dev/loop0 67M 67M 0 100% /var/lib/snapd/snap/core24/1225 /dev/loop1 72M 72M 0 100% /var/lib/snapd/snap/certbot/5214 /dev/nvme0n1p2 960M 472M 489M 50% /boot /dev/nvme0n1p1 599M 8.5M 591M 2% /boot/efi tmpfs 1.0M 0 1.0M 0% /run/credentials/getty@tty1.service tmpfs 347M 16K 347M 1% /run/user/1000 /dev/loop3 67M 67M 0 100% /var/lib/snapd/snap/core24/1237 /dev/loop4 72M 72M 0 100% /var/lib/snapd/snap/certbot/5234 |
②Create a dummy file to achieve at least 80% utilization(In the example, it is called "dummyfile" and is about 6G)
|
1 |
# dd if=/dev/zero of=dummyfile bs=1M count=6000 |
③check again
Confirm that it is above 80% by performing the following
|
1 |
# df -h |
④Run check scripts
|
1 |
# /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: 86 %".
⑤Delete "dummyfile"
|
1 |
# rm dummyfile |
⑥Periodic Execution Setting
|
1 2 3 |
# crontab -e Add the following 30 2 * * * /var/www/system/disk_capacity_check.sh |
