1. Admin 2

2. Ports Well known ports, registered ports, dynamic ports 0-65535
– WNP, 1024 – – RP, DP
80 = HTTP, 25 = SMTP, 22 = SSH, 389 = LDAP
Daemons often 'listen' for connections on these ports

3. Services Services run in the background Apache, Exim, Ldap, mysql
Can be started and stopped using
/etc/init.d/apache2 start|stop|restart...
Don't kill, stop the service instead

4. Configuration /etc/ contains most configuration files
motd, resolv.conf, apache, aliases
/etc/apache2/sites-available
a2ensite creates symlinks in sites-enabled

5. Exim (Experimental Internet Mailer)
Exim is a MTA (mail transfer agent)

6. Exim exim -bpc – Count of messages on the queue
exim -bp | exiqsumm – More details
exiwhat – What is exim doing?
Best exim cheatsheet in the world;
t.php

7. Creating mysql databases
mysql -u root -p
CREATE DATABASE username
GRANT USAGE ON *.* TO IDENTIFIED BY 'somepassword'
GRANT ALL PRIVILEGES ON username.* TO

8. LDAP Lightweight Directory Access Protocol
"dc=compsoc,dc=nuigalway,dc=ie"
Groups – admin, committee, compsocweb
Everyone under ”People”
Administrated using phpldapadmin
ssh -L 3044:localhost:80
Create accounts, delete accounts etc.

9. RAID Management
RAID 0,2,3 – Speed, 1 – Mirroring, others are a combination.
mdadm command
cat /proc/mdstat
mdadm --manage /dev/md1 --remove /dev/sda2
sfdisk -d /dev/sda | sfdisk /dev/sdb
mdadm --manage /dev/md0 --add /dev/sda1

10. cron Scheduled tasks What does this do?
minute hour dom month dow user cmd
01 * * * * root echo "This command is run at one min past every hour"
17 8 * * * root echo "This command is run daily at 8:17 am"
17 20 * * * root echo "This command is run daily at 8:17 pm"
00 4 * * 0 root echo "This command is run at 4 am every Sunday"
* 4 * * Sun root echo "So is this"
* * root echo "This command is run 4:42 am every 1st of the month"
01 * * root echo "This command is run hourly on the 19th of July
What does this do?
0 2 * * * root /root/bin/make_snapshot.sh