1.
Your Inner Sysadmin
Chris Tankersley
@dragonmantank
MidwestPHP 2015
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2.
Who Am I
• PHP Programmer for over
10 years
• Sysadmin/DevOps for
around 8 years
• Using Linux for more than
15 years
• https://github.com/dragon
mantank
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3.
Here Be Dragons
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4.
Traditional Lamp Stack
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5.
Our Players
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6.
And of course…
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7.
The Server
• /bin - Essential user executable files
• /boot - Stuff that makes the OS boot up!
• /dev - Special device stuff you probably won't
touch
• /etc - Configuration files
• /home - User home directories
• /sbin - System binaries
• /usr - Multi-user apps and utilities
• /var - Data usually lives here
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8.
Installing Software
• Compile software from scratch
• Use the package manager (yum/apt)
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9.
Learn to love the Command
Line
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10.
Learn a CLI text editor
• vi/vim
• emacs
• nano
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11.
Authentication and
Authorization
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12.
sudo
You can give admin access to users (or groups of
users) without giving them root.
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# Add sudo access to a single user to run as root
dragonmantank ALL=(ALL) ALL
# Add sudo access to a full group
%admin ALL=(ALL) ALL
You can even restrict what commands the users can run
# Restrict web developers to only restart Apache and MySQL
%webdevs 192.168.1.0/255.255.225.0=(root)
NOPASSWD:/usr/sbin/service apache2 restart, /usr/sbin/service
mysql restart

13.
Jailing Users
Keeps people from getting to things they shouldn't.
Protects the users from themselves.
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14.
Jailed Shells
Gives users a full shell but not the entire file system.
You can pick and choose what programs the user can
have access too. Jailkit makes this incredibly easy to
set up.
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15.
Jailed SFTP
Locks the user to a specific base path, but doesn’t
give them a shell, much like FTP. You get the security
of SSH though! It does require a system user
however.
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16.
Jailing SFTP
# In /etc/ssh/sshd_config
Subsystem ftp sftp-internal
# At the bottom of the file
Match User jailedsftp
ChrootDirectory /some/path
AllowTCPForwarding no
X11Forwarding no
ForceCommand internal-sftp
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17.
Docker
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If you do it the non-Docker way

18.
Scripting Languages
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19.
Bash
Most servers use bash as the default shell. Most
shells understand bash's syntax. If you find yourself
running the same commands over and over, throw it
in a bash script.
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20.
Python
Ships with most distros.
Great for when you need
more power than what
bash has.
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21.
PHP!
Leverage your PHP skills to write shell scripts.
• Symfony Console Component
• Aura CLI
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22.
Locking Down your Code
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23.
Running Apache as a different
user
MPM-ITK
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MOD_RUID2
<IfModule mpm_itk_module>
AssignUserId [user] [user]
</IfModule>
RMode config
RUidGid myuser mygroup
RDocumentChRoot
/var/www/vhosts/domain.com/
www/public

24.
PHP-FPM
user = myuser
group = mygroup
chroot = /path/to/my/chroot
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25.
Logs
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26.
Logrotate
Rotates logs out for organization (or other purposes)
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weekly
rotate 4
create
include /etc/logrotate.d
/var/log/wtmp {
monthly
minsize 1M
create 0664 root utmp
rotate 1
}

27.
Logwatch
Script that runs every so often and scans a bunch of logs
so you get a pretty e-mail with a summary of events
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--------------------- httpd Begin ------------------------
0.17 MB transferred in 792 responses (1xx 0, 2xx 786, 3xx 0, 4xx 6, 5xx 0)
199 Content pages (0.09 MB),
593 Other (0.09 MB)
Requests with error response codes
400 Bad Request
/w00tw00t.at.ISC.SANS.DFind:): 1 Time(s)
404 Not Found
/MyAdmin/scripts/setup.php: 1 Time(s)
/phpmyadmin/scripts/setup.php: 1 Time(s)
/w00tw00t.at.blackhats.romanian.anti-sec:): 1 Time(s)
/webdav/: 2 Time(s)
---------------------- httpd End -------------------------

28.
OSSEC
Actually a Host Intrusion Detection system, but it does
this by watching logs. Will alert you immediately to
problems, and even shut down the attacks.
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OSSEC HIDS Notification.
2012 Oct 24 11:38:10
Received From: maple->/var/log/auth.log
Rule: 5712 fired (level 10) -> "SSHD brute force trying to get
access to the system."
Portion of the log(s):
Oct 24 11:38:09 maple sshd[1062]: Failed password for invalid
user alias from 199.167.138.44 port 59988 ssh2
Oct 24 11:38:07 maple sshd[1062]: Invalid user alias from
199.167.138.44
Oct 24 11:38:06 maple sshd[1059]: Failed password for invalid
user recruit from 199.167.138.44 port 59884 ssh2

29.
Preventing Intruders
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30.
hosts.deny and hosts.allow
Set of files to allow or deny access to the machine or
certain apps/ports on the machine
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31.
IPTables
A firewall that is generally available on Linux
machines that can be configured many different ways
to allow or block or mangle traffic
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32.
OSSEC
IDS that was logs and will use hosts.deny and
iptables to block stuff automatically for you!
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33.
Configuration Management
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34.
What is Configuration
Management?
Process by which you figure out what goes on your
servers, how you want them set up, and keeping
track of that information. Files are usually stored in
source control on one server and pushed to clients.
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35.
Why do you need it?
• Ever needed to keep track of when files get
changed?
• Ever needed to roll back a change?
• Ever needed to push the same change to a bunch
of servers
• Ever needed to set up a server exactly the same
way as another server?
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36.
General CM Workflow
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Write a Manifest
file
Client checks and
compiles the
manifests
Client makes
changes based on
manifests

37.
Ansible
• https://serversforhackers.com/getting-started-
with-ansible/
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38.
Puppet
• http://www.erikaheidi.com/page/vagrant
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39.
Server Monitoring
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40.
Quick Poll
• Who here knows that their server is up right now?
• Are all of the required services running?
• Are there enough resources currently available?
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41.
Service Monitoring with Monit
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42.
Host Monitoring with Icinga
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43.
Software Tools
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44.
tmux/screen
Command line multiplexer
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45.
tail
Look at the newest entries in a log, or even watch log
files as they are generated
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46.
curl
Command line program for transferring data via a URL
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47.
iftop
Displays a breakdown of bandwidth usage by host
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48.
htop
Slightly better interface for checking memory and
CPU usage
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49.
tcpdump
Allows you to view and record data transmitted over
the network. Couple this with wireshark and you can
inspect the packets!
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50.
Servers for Hackers
Chris Fidao
@fideloper
http://serversforhackers.
com
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51.
Questions?
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52.
Thank You!
http://ctankersley.com
chris@ctankersley.com
@dragonmantank
https://joind.in/13069
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