OracleLinux8.6 : Logwatch , DNS update ・disk usage check script

Contents

1. Logwatch
2.Automatic DNS update script
3.Disk Usage Check Script
- 3.1 script
- 3.2 Execution check

1. Logwatch

①Install

# dnf install logwatch

1	# dnf install logwatch

②Editing Configuration Files

# cat /usr/share/logwatch/default.conf/logwatch.conf >> /etc/logwatch/conf/logwatch.conf
# vi /etc/logwatch/conf/logwatch.conf

1 2	# cat /usr/share/logwatch/default.conf/logwatch.conf >> /etc/logwatch/conf/logwatch.conf # vi /etc/logwatch/conf/logwatch.conf

●Per Line 45
Insert "#" at the beginning of the "MailTo = root" line and set the email address you want to receive notifications to the line below it.
#MailTo = root
MailTo = <mail address>
●Per Line 79 Set the level of detail for log notifications
#Detail = Low
Detail = High

●Per Line 45

Insert "#" at the beginning of the "MailTo = root" line and set the email address you want to receive notifications to the line below it.

#MailTo = root

MailTo = <mail address>

●Per Line 79 Set the level of detail for log notifications

#Detail = Low

Detail = High

③Output Logwatch reports

# logwatch --output stdout

1	# logwatch --output stdout

You will get the following message


 ################### Logwatch 7.4.3 (04/27/16) ####################
        Processing Initiated: Mon Sep  5 09:18:13 2022
        Date Range Processed: yesterday
                              ( 2022-Sep-04 )
                              Period is day.
        Detail Level of Output: 10
        Type of Output/Format: stdout / text
        Logfiles for Host: Lepard
 ##################################################################
--------------------- Amavisd-new Begin ------------------------

Redundant argument in sprintf at /usr/share/logwatch/scripts/services/amavis line 1338, <> line 31.

<abbreviation>

--------------------- Disk Space Begin ------------------------

 Filesystem                  Size  Used Avail Use% Mounted on
 devtmpfs                    828M     0  828M   0% /dev
 /dev/mapper/ol_lepard-root   17G  6.6G   11G  39% /
 /dev/nvme0n1p1             1014M  350M  665M  35% /boot


 ---------------------- Disk Space End -------------------------


 --------------------- lm_sensors output Begin ------------------------

 nvme-pci-0b00
 Adapter: PCI adapter
 Composite:   +11758.9 C


 ---------------------- lm_sensors output End -------------------------


 ###################### Logwatch End #########################

You will get the following message

################### Logwatch 7.4.3 (04/27/16) ####################

Processing Initiated: Mon Sep 5 09:18:13 2022

Date Range Processed: yesterday

( 2022-Sep-04 )

Period is day.

Detail Level of Output: 10

Type of Output/Format: stdout / text

Logfiles for Host: Lepard

##################################################################

--------------------- Amavisd-new Begin ------------------------

Redundant argument in sprintf at /usr/share/logwatch/scripts/services/amavis line 1338, <> line 31.

--------------------- Disk Space Begin ------------------------

Filesystem Size Used Avail Use% Mounted on

devtmpfs 828M 0 828M 0% /dev

/dev/mapper/ol_lepard-root 17G 6.6G 11G 39% /

/dev/nvme0n1p1 1014M 350M 665M 35% /boot

---------------------- Disk Space End -------------------------

--------------------- lm_sensors output Begin ------------------------

nvme-pci-0b00

Adapter: PCI adapter

Composite: +11758.9 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.

# /etc/cron.daily/0logwatch

1	# /etc/cron.daily/0logwatch

2.Automatic DNS update script

Whenever the global IP changes, which happens when the network is disconnected or the router is disconnected and rebooted, we need to access Dynamic DNS to inform the user that the global IP has changed. We will install a script that will do this automatically.
This time, we assume that you will use Value Domain as your DNS service.

①Shell script for updating

Set DOMAINNAME= , PASSWORD= , HOSTNAME= to update a specific host such as login.example.com, HOSTNAME=login.

Content "dns_update.sh"

#/bin/bash

#VARIABLES
DOMAINNAME="example.com"
PASSWORD="password"
HOSTNAME="*"
MYIP=""

#External IP Acquisitions
MYIP=`wget -q -O - "https://dyn.value-domain.com/cgi-bin/dyn.fcg?ip"`
#SLEEP because cgi can become busy
sleep 5
#update process
wget -q -O - "https://dyn.value-domain.com/cgi-bin/dyn.fcg?d=$DOMAINNAME&p=$PASSWORD&h=$HOSTNAME&i=$MYIP"

#/bin/bash

#VARIABLES

DOMAINNAME="example.com"

PASSWORD="password"

HOSTNAME="*"

MYIP=""

#External IP Acquisitions

MYIP=`wget -q -O - "https://dyn.value-domain.com/cgi-bin/dyn.fcg?ip"`

#SLEEP because cgi can become busy

sleep 5

#update process

wget -q -O - "https://dyn.value-domain.com/cgi-bin/dyn.fcg?d=$DOMAINNAME&p=$PASSWORD&h=$HOSTNAME&i=$MYIP"

②Automatic Renewal Settings
Add the script to the crontab so that it is updated periodically

# crontab -e

* 1 * * * /root/dns_update.sh

# crontab -e

* 1 * * * /root/dns_update.sh

3.Disk Usage Check Script

3.1 script

# cd /var/www/system
# vi disk_capacity_check.sh

1 2	# cd /var/www/system # vi disk_capacity_check.sh

Contents of disk_capacity_check.sh

#!/bin/bash

#Specify e-mail address for notification
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

#!/bin/bash

#Specify e-mail address for notification

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

# chmod 700 disk_capacity_check.sh

1	# chmod 700 disk_capacity_check.sh

3.2 Execution check

①Check current utilization

# df -h

# df -h

It appears as follows

Filesystem           Size  Used Avail Use% Mounted on
devtmpfs             1.8G     0  1.8G   0% /dev
tmpfs                1.8G     0  1.8G   0% /dev/shm
tmpfs                1.8G  8.8M  1.8G   1% /run
tmpfs                1.8G     0  1.8G   0% /sys/fs/cgroup
/dev/mapper/ol-root   17G   17G  450M  98% /
/dev/nvme0n1p1      1014M  282M  733M  28% /boot
tmpfs                362M     0  362M   0% /run/user/1000

Filesystem Size Used Avail Use% Mounted on

devtmpfs 1.8G 0 1.8G 0% /dev

tmpfs 1.8G 0 1.8G 0% /dev/shm

tmpfs 1.8G 8.8M 1.8G 1% /run

tmpfs 1.8G 0 1.8G 0% /sys/fs/cgroup

/dev/mapper/ol-root 17G 17G 450M 98% /

/dev/nvme0n1p1 1014M 282M 733M 28% /boot

tmpfs 362M 0 362M 0% /run/user/1000

②Create a dummy file to have at least 80% utilization (in the example, it is named "dummyfile" and is about 9G).

# dd if=/dev/zero of=dummyfile bs=1M count=9000

1	# dd if=/dev/zero of=dummyfile bs=1M count=9000

③Reconfirmation

# df -h

# df -h

Confirmation that it is above 80%.

④Run Script

# /var/www/system/disk_capacity_check.sh

1	# /var/www/system/disk_capacity_check.sh

You will receive an e-mail to the e-mail address you have set up with the body of the message as "Disk usage alert : 98%".

⑤Delete the "dummyfile" you created.

# rm dummyfile

1	# rm dummyfile

⑥Periodic Execution Setting

# crontab -e
30　2　*　*　*　/var/www/system/disk_capacity_check.sh

1 2	# crontab -e 30　2　*　*　*　/var/www/system/disk_capacity_check.sh

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