InfoSec Addicts Intro to Linux

#####################################
# InfoSecAddicts Intro to Linux     #
# By Joe McCray                     #
#####################################



##########
# VMWare #
##########
- For this workshop you'll need the latest version of VMWare Workstation (Windows), Fusion (Mac), or Player.

- http://www.vmware.com/ap/products/player.html


- Although you can get the VM to run in VirtualBox, I will not be supporting this configuration for this class.


##########################
# Download the attack VM #
##########################
https://s3.amazonaws.com/infosecaddictsvirtualmachines/InfoSecAddictsVM.zip
user:      infosecaddicts
pass:      infosecaddicts

- Here is a good set of slides for getting started with Linux:
http://www.slideshare.net/olafusimichael/linux-training-24086319




- Log in to your Ubuntu host with the following credentials:
	user:      infosecaddicts
	pass:      infosecaddicts



- I prefer to use Putty to SSH into my Ubuntu host on pentests and I'll be teaching this class in the same manner that I do pentests.
- You can download Putty from here:
- http://the.earth.li/~sgtatham/putty/latest/x86/putty.exe


- For the purpose of this workshop 192.168.230.128 is my Ubuntu IP address so anytime you see that IP you'll know that's my Ubuntu host



########################
# Basic Linux Commands #
########################
cd ~

pwd

whereis pwd

which pwd

sudo find / -name pwd

/bin/pwd

mkdir LinuxBasics

cd LinuxBasics

touch one two three

ls -l t		(without pressing the Enter key, press the Tab key twice. What happens?)

h		(and again without pressing the Enter key, press the Tab key twice. What happens?)

Press the 'Up arrow key'	(What happens?)

Press 'Ctrl-A'			(What happens?)

ls

clear				(What happens?)

echo one > one

cat one				(What happens?)

man cat				(What happens?)
	q

cat two

cat one > two

cat two

cat one two > three

cat three

echo four >> three

cat three 			(What happens?)

wc -l three

man wc
	q

cat three | grep four

cat three | grep one

man grep
	q


man ps
	q

ps

ps aux

ps aux | less

Press the 'Up arrow key'	(What happens?)

Press the 'Down arrow key'	(What happens?)
	q

top



#########
# Files #
#########
cd ~

pwd

ls

cd LinuxBasics

pwd

cd ~

pwd

cd LinuxBasics

ls

mkdir files

cp one files/

ls files/

cd files/

cp ../two .

ls

cp ../three .

ls

tar cvf files.tar *

ls

gzip files.tar

ls

rm -rf one two three

ls

tar -zxvf files.tar.gz

rm -rf files.tar.gz

sudo apt install -y zip unzip

zip data *

unzip -l data.zip

unzip data.zip -d /tmp

unzip -l data.zip



############
# VIM Demo #
############
cd ~
sudo apt install -y vim
     infosecaddicts

cd LinuxBasics

mkdir vimlesson

cd vimlesson

vi lesson1.sh

i			(press "i" to get into INSERT mode and then paste in the lines below)

#!/bin/bash

echo "This is my first time using vi to create a shell script"
echo " "
echo " "
echo " "
sleep 5
echo "Ok, now let's clear the screen"
sleep 3


---------------don't put this line in your script----------------------------

ESC			(press the ESC key to get you out of INSERT mode)

[SHIFT+:]	(press SHIFT and the : keys at the same time and you should see a : in the bottom left corner of the screen.


wq			(typing "wq" immediately after SHIFT: will save (w for write, and q for quit meaning exit vim).



vi lesson1.sh

[SHIFT+:]	(press SHIFT and the : keys at the same time and you should see a : in the bottom left corner of the screen.

set number 	(typing "set number" immediately after SHIFT: will add line numbers to vim).

wq			(typing "wq" immediately after SHIFT: will save (w for write, and q for quit meaning exit vim).




vi lesson1.sh

[SHIFT+:]	(press SHIFT and the : keys at the same time and you should see a : in the bottom left corner of the screen.

set number 	(typing "set number" immediately after SHIFT: will add line numbers to vim).


[SHIFT+:]	(press SHIFT and the : keys at the same time and you should see a : in the bottom left corner of the screen.

/echo		(typing "/echo" immediately after SHIFT: will search the file for the word echo).

[SHIFT+:]	(press SHIFT and the : keys at the same time and you should see a : in the bottom left corner of the screen.

wq			(typing "wq" immediately after SHIFT: will save (w for write, and q for quit meaning exit vim).




vi lesson1.sh

[SHIFT+:]	(press SHIFT and the : keys at the same time and you should see a : in the bottom left corner of the screen.

set number 	(typing "set number" immediately after SHIFT: will add line numbers to vim).


[SHIFT+:]	(press SHIFT and the : keys at the same time and you should see a : in the bottom left corner of the screen.

4		(typing "4" immediately after SHIFT: will take you to line number 4).

[SHIFT+:]	(press SHIFT and the : keys at the same time and you should see a : in the bottom left corner of the screen.

wq			(typing "wq" immediately after SHIFT: will save (w for write, and q for quit meaning exit vim).




vi lesson1.sh

[SHIFT+:]	(press SHIFT and the : keys at the same time and you should see a : in the bottom left corner of the screen.

set number 	(typing "set number" immediately after SHIFT: will add line numbers to vim).


[SHIFT+:]	(press SHIFT and the : keys at the same time and you should see a : in the bottom left corner of the screen.

4		(typing "4" immediately after SHIFT: will take you to line number 4).

dd		(typing "dd" will delete the line that you are on)

[SHIFT+:]	(press SHIFT and the : keys at the same time and you should see a : in the bottom left corner of the screen.

wq			(typing "wq" immediately after SHIFT: will save (w for write, and q for quit meaning exit vim).




vi lesson1.sh

[SHIFT+:]	(press SHIFT and the : keys at the same time and you should see a : in the bottom left corner of the screen.

set number 	(typing "set number" immediately after SHIFT: will add line numbers to vim).


[SHIFT+:]	(press SHIFT and the : keys at the same time and you should see a : in the bottom left corner of the screen.

4		(typing "4" immediately after SHIFT: will take you to line number 4).

dd		(typing "dd" will delete the line that you are on)

[SHIFT+:]	(press SHIFT and the : keys at the same time and you should see a : in the bottom left corner of the screen.

syntax on		(typing "syntax on" immediately after SHIFT: will turn on syntax highlighting

[SHIFT+:]	(press SHIFT and the : keys at the same time and you should see a : in the bottom left corner of the screen.

set tabstop=5	(typing "set tabstop=5" immediately after SHIFT: will set your tabs to 5 spaces

[SHIFT+:]	(press SHIFT and the : keys at the same time and you should see a : in the bottom left corner of the screen.

wq			(typing "wq" immediately after SHIFT: will save (w for write, and q for quit meaning exit vim).




vi .vimrc
i			(press "i" to get into INSERT mode and then paste in the lines below)


set number
syntax on
set tabstop=5


[SHIFT+:]	(press SHIFT and the : keys at the same time and you should see a : in the bottom left corner of the screen.

wq			(typing "wq" immediately after SHIFT: will save (w for write, and q for quit meaning exit vim).






vi lesson1.sh

[SHIFT+:]	(press SHIFT and the : keys at the same time and you should see a : in the bottom left corner of the screen.

echo $MYVIMRC	(typing "echo $MYVIMRC" immediately after SHIFT: will display the path to your new .vimrc file

[SHIFT+:]	(press SHIFT and the : keys at the same time and you should see a : in the bottom left corner of the screen.

wq			(typing "wq" immediately after SHIFT: will save (w for write, and q for quit meaning exit vim).


###############
# Permissions #
###############
cd ~

pwd

ls

cd LinuxBasics

ls -l one

We can determine a lot from examining the results of this command. The file "one" is owned by user "me".
Now "me" has the right to read and write this file.
The file is owned by the group "me". Members of the group "me" can also read and write this file.
Everybody else can read this file



ls -l /bin/bash


Here we can see:

The file "/bin/bash" is owned by user "root". The superuser has the right to read, write, and execute this file.
The file is owned by the group "root". Members of the group "root" can also read and execute this file.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              Everybody else can read and execute this file


The next command you need to know is "chmod"
rwx rwx rwx = 111 111 111
rw- rw- rw- = 110 110 110
rwx --- --- = 111 000 000

and so on...

rwx = 111 in binary = 7
rw- = 110 in binary = 6
r-x = 101 in binary = 5
r-- = 100 in binary = 4

ls -l one

chmod 600 one

ls -l one

sudo useradd testuser
     infosecaddicts

sudo passwd testuser

testuser
testuser

sudo chown testuser one
     infosecaddicts

ls -l one

sudo chgrp testuser one
     infosecaddicts

ls -l one

id

su testuser
testuser


Here is a table of numbers that covers all the common settings. The ones beginning with "7" are used with programs (since they enable execution) and the rest are for other kinds of files.

Value	Meaning
777 (rwxrwxrwx) No restrictions on permissions. Anybody may do anything. Generally not a desirable setting.

755 (rwxr-xr-x) The file's owner may read, write, and execute the file. All others may read and execute the file. This setting is common for programs that are used by all users.

700 (rwx------) The file's owner may read, write, and execute the file. Nobody else has any rights. This setting is useful for programs that only the owner may use and must be kept private from others.

666 (rw-rw-rw-) All users may read and write the file.

644 (rw-r--r--) The owner may read and write a file, while all others may only read the file. A common setting for data files that everybody may read, but only the owner may change.

600 (rw-------) The owner may read and write a file. All others have no rights. A common setting for data files that the owner wants to keep private.



Directory permissions
---------------------
The chmod command can also be used to control the access permissions for directories. In most ways, the permissions scheme for directories works the same way as they do with files. However, the execution permission is used in a different way. It provides control for access to file listing and other things. Here are some useful settings for directories:

Value	Meaning
777 (rwxrwxrwx) No restrictions on permissions.
Anybody may list files, create new files in the directory and delete files in the directory.
Generally not a good setting.



755 (rwxr-xr-x) The directory owner has full access.
All others may list the directory, but cannot create files nor delete them.
This setting is common for directories that you wish to share with other users.



700 (rwx------) The directory owner has full access. Nobody else has any rights. This setting is useful for directories that only the owner may use and must be kept private from others.

######################
# Process Management #
######################
top

sudo apt install -y htop
     infosecaddicts

htop

ps

ps aux

ps -A

ps -A | less

ps axjf

pstree

pgrep bash

pgrep init

ps aux | grep apache

You can list all of the signals that are possible to send with kill by typing:

kill -l

sudo kill -HUP pid_of_apache

The pkill command works in almost exactly the same way as kill, but it operates on a process name instead:

pkill -9 ping
The above command is the equivalent of:

kill -9 `pgrep ping`





####################
# MD5 Hashing Demo #
####################
cd ~/LinuxBasics
mkdir hashdemo
cd hashdemo
echo test > test.txt
cat test.txt
md5sum test.txt
echo hello >> test.txt
cat test.txt
md5sum test.txt
cd ..




#################################
# Symmetric Key Encryption Demo #
#################################
cd ~/LinuxBasics
mkdir gpgdemo
cd gpgdemo
echo test > test.txt
cat test.txt
gpg -c test.txt
	password
	password
ls | grep test
cat test.txt
cat test.txt.gpg
rm -rf test.txt
ls | grep test
gpg -o output.txt test.txt.gpg
cat output.txt


#########################################################################################################################
# Asymmetric Key Encryption Demo 											                                            #
#															                                                            #
# Configure random number generator 											                                        #
# https://www.howtoforge.com/helping-the-random-number-generator-to-gain-enough-entropy-with-rng-tools-debian-lenny	    #
#########################################################################################################################

sudo apt install -y rng-tools
     infosecaddicts

/etc/init.d/rng-tools start

sudo rngd -r /dev/urandom
     infosecaddicts


echo hello > file1.txt
echo goodbye > file2.txt
echo green > file3.txt
echo blue > file4.txt

tar czf files.tar.gz *.txt

gpg --gen-key
	1
	1024
	0
	y
	John Doe
	[email protected]
	--blank comment--
	O
		password
		password



gpg --armor --output file-enc-pubkey.txt --export 'John Doe'

cat file-enc-pubkey.txt

gpg --armor --output file-enc-privkey.asc --export-secret-keys 'John Doe'

cat file-enc-privkey.asc

gpg --encrypt --recipient 'John Doe' files.tar.gz

rm -rf files.tar.gz *.txt

ls

tar -zxvf files.tar.gz.gpg

gpg --output output.tar.gz --decrypt files.tar.gz.gpg
	password

tar -zxvf output.tar.gz

ls





############################
# Encryption using OpenSSL #
############################
openssl genrsa -out private_key.pem 1024
openssl rsa -in private_key.pem -out public_key.pem -outform PEM -pubout


echo hello > encrypt.txt
openssl rsautl -encrypt -inkey public_key.pem -pubin -in encrypt.txt -out encrypt.dat

cat encrypt.dat

rm -rf encrypt.txt

ls

openssl rsautl -decrypt -inkey private_key.pem -in encrypt.dat -out decrypt.txt

cat decrypt.txt



###############################
# Secure File/Folder Deletion #
###############################
sudo apt install -y secure-delete wipe

wget https://www.sans.org/security-resources/tcpip.pdf

file tcpip.pdf

sudo srm tcpip.pdf

wget https://www.sans.org/security-resources/tcpip.pdf

shred tcpip.pdf

wget https://www.sans.org/security-resources/tcpip.pdf

wipe tcpip.pdf





#################
# IPTables Demo #
#################
cd ~

- Delete Existing Rules
---------------------
sudo /sbin/iptables -F
     infosecaddicts

	(or)

sudo /sbin/iptables --flush
     infosecaddicts



- Set Default Chain Policies
--------------------------
iptables -P INPUT DROP
iptables -P FORWARD DROP
iptables -P OUTPUT DROP



- Delete Existing Rules
---------------------
sudo /sbin/iptables -F
     infosecaddicts

	(or)

sudo /sbin/iptables --flush
     infosecaddicts




sudo /bin/bash



- Block a Specific ip-address
-----------------------------
BLOCK_THIS_IP="1.2.3.4"
iptables -A INPUT -s "$BLOCK_THIS_IP" -j DROP


iptables -A INPUT -i eth0 -s "$BLOCK_THIS_IP" -j DROP
iptables -A INPUT -i eth0 -p tcp -s "$BLOCK_THIS_IP" -j DROP


- Allow ALL Incoming SSH
------------------------
iptables -A INPUT -i eth0 -p tcp --dport 22 -m state --state NEW,ESTABLISHED -j ACCEPT
iptables -A OUTPUT -o eth0 -p tcp --sport 22 -m state --state ESTABLISHED -j ACCEPT


- Allow Incoming SSH only from a Sepcific Network
-------------------------------------------------
iptables -A INPUT -i eth0 -p tcp -s 192.168.100.0/24 --dport 22 -m state --state NEW,ESTABLISHED -j ACCEPT
iptables -A OUTPUT -o eth0 -p tcp --sport 22 -m state --state ESTABLISHED -j ACCEPT


- Allow Incoming HTTP and HTTPS
-------------------------------
iptables -A INPUT -i eth0 -p tcp --dport 80 -m state --state NEW,ESTABLISHED -j ACCEPT
iptables -A OUTPUT -o eth0 -p tcp --sport 80 -m state --state ESTABLISHED -j ACCEPT


iptables -A INPUT -i eth0 -p tcp --dport 443 -m state --state NEW,ESTABLISHED -j ACCEPT
iptables -A OUTPUT -o eth0 -p tcp --sport 443 -m state --state ESTABLISHED -j ACCEPT



- Combine Multiple Rules Together using MultiPorts
--------------------------------------------------
iptables -A INPUT -i eth0 -p tcp -m multiport --dports 22,80,443 -m state --state NEW,ESTABLISHED -j ACCEPT
iptables -A OUTPUT -o eth0 -p tcp -m multiport --sports 22,80,443 -m state --state ESTABLISHED -j ACCEPT


- Allow Outgoing SSH
--------------------
iptables -A OUTPUT -o eth0 -p tcp --dport 22 -m state --state NEW,ESTABLISHED -j ACCEPT
iptables -A INPUT -i eth0 -p tcp --sport 22 -m state --state ESTABLISHED -j ACCEPT


- Allow Outgoing SSH only to a Specific Network
-----------------------------------------------
The following rules allow outgoing ssh connection only to a specific network. i.e You an ssh only to 192.168.100.0/24 network from the inside.

iptables -A OUTPUT -o eth0 -p tcp -d 192.168.100.0/24 --dport 22 -m state --state NEW,ESTABLISHED -j ACCEPT
iptables -A INPUT -i eth0 -p tcp --sport 22 -m state --state ESTABLISHED -j ACCEPT



- Allow Outgoing HTTPS
----------------------
The following rules allow outgoing secure web traffic. This is helpful when you want to allow internet traffic for your users. On servers, these rules are also helpful when you want to use wget to download some files from outside.

iptables -A OUTPUT -o eth0 -p tcp --dport 443 -m state --state NEW,ESTABLISHED -j ACCEPT
iptables -A INPUT -i eth0 -p tcp --sport 443 -m state --state ESTABLISHED -j ACCEPT




Load Balance Incoming Web Traffic
---------------------------------
You can also load balance your incoming web traffic using iptables firewall rules.

This uses the iptables nth extension. The following example load balances the HTTPS traffic to three different ip-address. For every 3th packet, it is load balanced to the appropriate server (using the counter 0).

iptables -A PREROUTING -i eth0 -p tcp --dport 443 -m state --state NEW -m nth --counter 0 --every 3 --packet 0 -j DNAT --to-destination 192.168.1.101:443
iptables -A PREROUTING -i eth0 -p tcp --dport 443 -m state --state NEW -m nth --counter 0 --every 3 --packet 1 -j DNAT --to-destination 192.168.1.102:443
iptables -A PREROUTING -i eth0 -p tcp --dport 443 -m state --state NEW -m nth --counter 0 --every 3 --packet 2 -j DNAT --to-destination 192.168.1.103:443



Allow Ping from Outside to Inside
---------------------------------
The following rules allow outside users to be able to ping your servers.

iptables -A INPUT -p icmp --icmp-type echo-request -j ACCEPT
iptables -A OUTPUT -p icmp --icmp-type echo-reply -j ACCEPT



Allow Ping from Inside to Outside
---------------------------------
The following rules allow you to ping from inside to any of the outside servers.

iptables -A OUTPUT -p icmp --icmp-type echo-request -j ACCEPT
iptables -A INPUT -p icmp --icmp-type echo-reply -j ACCEPT



Allow Loopback Access
---------------------
You should allow full loopback access on your servers. i.e access using 127.0.0.1

iptables -A INPUT -i lo -j ACCEPT
iptables -A OUTPUT -o lo -j ACCEPT



Allow Internal Network to External network
------------------------------------------
On the firewall server where one ethernet card is connected to the external, and another ethernet card connected to the internal servers, use the following rules to allow internal network talk to external network.

In this example, eth1 is connected to external network (internet), and eth0 is connected to internal network (For example: 192.168.1.x).

iptables -A FORWARD -i eth0 -o eth1 -j ACCEPT



Allow outbound DNS
------------------
The following rules allow outgoing DNS connections.

iptables -A OUTPUT -p udp -o eth0 --dport 53 -j ACCEPT
iptables -A INPUT -p udp -i eth0 --sport 53 -j ACCEPT



Allow Rsync From a Specific Network
-----------------------------------
The following rules allows rsync only from a specific network.

iptables -A INPUT -i eth0 -p tcp -s 192.168.101.0/24 --dport 873 -m state --state NEW,ESTABLISHED -j ACCEPT
iptables -A OUTPUT -o eth0 -p tcp --sport 873 -m state --state ESTABLISHED -j ACCEPT



Allow MySQL connection only from a specific network
---------------------------------------------------
If you are running MySQL, typically you don’t want to allow direct connection from outside. In most cases, you might have web server running on the same server where the MySQL database runs.

However DBA and developers might need to login directly to the MySQL from their laptop and desktop using MySQL client. In those case, you might want to allow your internal network to talk to the MySQL directly as shown below.

iptables -A INPUT -i eth0 -p tcp -s 192.168.100.0/24 --dport 3306 -m state --state NEW,ESTABLISHED -j ACCEPT
iptables -A OUTPUT -o eth0 -p tcp --sport 3306 -m state --state ESTABLISHED -j ACCEPT



Allow Sendmail or Postfix Traffic
---------------------------------
The following rules allow mail traffic. It may be sendmail or postfix.

iptables -A INPUT -i eth0 -p tcp --dport 25 -m state --state NEW,ESTABLISHED -j ACCEPT
iptables -A OUTPUT -o eth0 -p tcp --sport 25 -m state --state ESTABLISHED -j ACCEPT


Allow IMAP and IMAPS
--------------------
The following rules allow IMAP/IMAP2 traffic.

iptables -A INPUT -i eth0 -p tcp --dport 143 -m state --state NEW,ESTABLISHED -j ACCEPT
iptables -A OUTPUT -o eth0 -p tcp --sport 143 -m state --state ESTABLISHED -j ACCEPT


The following rules allow IMAPS traffic.

iptables -A INPUT -i eth0 -p tcp --dport 993 -m state --state NEW,ESTABLISHED -j ACCEPT
iptables -A OUTPUT -o eth0 -p tcp --sport 993 -m state --state ESTABLISHED -j ACCEPT




Allow POP3 and POP3S
--------------------
The following rules allow POP3 access.

iptables -A INPUT -i eth0 -p tcp --dport 110 -m state --state NEW,ESTABLISHED -j ACCEPT
iptables -A OUTPUT -o eth0 -p tcp --sport 110 -m state --state ESTABLISHED -j ACCEPT
The following rules allow POP3S access.

iptables -A INPUT -i eth0 -p tcp --dport 995 -m state --state NEW,ESTABLISHED -j ACCEPT
iptables -A OUTPUT -o eth0 -p tcp --sport 995 -m state --state ESTABLISHED -j ACCEPT



Port Forwarding
---------------
The following example routes all traffic that comes to the port 442 to 22. This means that the incoming ssh connection can come from both port 22 and 422.

iptables -t nat -A PREROUTING -p tcp -d 192.168.102.37 --dport 422 -j DNAT --to 192.168.102.37:22

If you do the above, you also need to explicitly allow incoming connection on the port 422.

iptables -A INPUT -i eth0 -p tcp --dport 422 -m state --state NEW,ESTABLISHED -j ACCEPT
iptables -A OUTPUT -o eth0 -p tcp --sport 422 -m state --state ESTABLISHED -j ACCEPT


Log Dropped Packets
-------------------
You might also want to log all the dropped packets. These rules should be at the bottom.

First, create a new chain called LOGGING.

iptables -N LOGGING
Next, make sure all the remaining incoming connections jump to the LOGGING chain as shown below.

iptables -A INPUT -j LOGGING
Next, log these packets by specifying a custom “log-prefix”.

iptables -A LOGGING -m limit --limit 2/min -j LOG --log-prefix "IPTables Packet Dropped: " --log-level 7
Finally, drop these packets.

iptables -A LOGGING -j DROP



#########################
# Ubuntu Perfect Server #
#########################

Reference:
https://www.howtoforge.com/tutorial/ubuntu-perfect-server-with-apache-php-myqsl-pureftpd-bind-postfix-doveot-and-ispconfig/


deb http://de.archive.ubuntu.com/ubuntu/ yakkety main restricted
deb http://de.archive.ubuntu.com/ubuntu/ yakkety-updates main restricted
deb http://de.archive.ubuntu.com/ubuntu/ yakkety universe
deb http://de.archive.ubuntu.com/ubuntu/ yakkety-updates universe
deb http://de.archive.ubuntu.com/ubuntu/ yakkety-updates multiverse


Then run
apt-get update

to update the apt package database and
apt-get upgrade

to install the latest updates (if there are any). If you see that a new kernel gets installed as part of the updates, you should reboot the system afterwards:
reboot

Change the Default Shell
/bin/sh is a symlink to /bin/dash, however we need /bin/bash, not /bin/dash. Therefore, we do this:
dpkg-reconfigure dash

Use dash as the default system shell (/bin/sh)? <-- No

Disable AppArmor
----------------
AppArmor is a security extension (similar to SELinux) that should provide extended security. In my opinion, you don't need it to configure a secure system, and it usually causes more problems than advantages (think of it after you have done a week of trouble-shooting because some service wasn't working as expected, and then you find out that everything was ok, only AppArmor was causing the problem). Therefore, I disable it (this is a must if you want to install ISPConfig later on).
We can disable it like this:

service apparmor stop
update-rc.d -f apparmor remove
apt-get remove apparmor apparmor-utils


apt-get -y install ntp ntpdate

Install Postfix, Dovecot, MariaDB, rkhunter and binutils
--------------------------------------------------------
For installing postfix, we need to ensure that sendmail is not installed and running. To stop and remove sendmail run this command:

service sendmail stop; update-rc.d -f sendmail remove




#######################
# Hardening Ubuntu 16 #
#######################

This guide is intended as a relatively easy step by step guide to:

Harden the security on an Ubuntu 16.04 LTS server by installing and configuring the following:

Install and configure Firewall - ufw
Secure shared memory - fstab
SSH - Key based login, disable root login and change port
Apache SSL - Disable SSL v3 support
Protect su by limiting access only to admin group
Harden network with sysctl settings
Disable Open DNS Recursion and Remove Version Info  - Bind9 DNS
Prevent IP Spoofing
Harden PHP for security
Restrict Apache Information Leakage
Install and configure Apache application firewall - ModSecurity
Protect from DDOS (Denial of Service) attacks with ModEvasive
Scan logs and ban suspicious hosts - DenyHosts and Fail2Ban
Intrusion Detection - PSAD
Check for RootKits - RKHunter and CHKRootKit
Scan open Ports - Nmap
Analyse system LOG files - LogWatch
Apparmor -  Application Armor
Audit your system security - Tiger and Tripwire
Requirements:

Ubuntu 16.04 LTS or later server with a standard LAMP stack installed.
1. Firewall - UFW

A good place to start is to install a Firewall.
UFW - Uncomplicated Firewall is a basic firewall that works very well and easy to configure with its Firewall configuration tool - gufw, or use  Shorewall, fwbuilder, or Firestarter.
Use Firestarter GUI to configure your firewall or refer to the Ubuntu Server Guide,  UFW manual pages or the Ubuntu UFW community documentation.
Install UFW and enable, open a terminal window and enter :
sudo apt-get install ufw
Allow SSH and Http services.
sudo ufw allow ssh
sudo ufw allow http
Enable the firewall.
sudo ufw enable
Check the status of the firewall.
sudo ufw status verbose
2. Secure shared memory.

Shared memory can be used in an attack against a running service. Modify /etc/fstab to make it more secure.
Open a Terminal Window and enter the following :
sudo vi /etc/fstab
Add the following line and save. You will need to reboot for this setting to take effect :
Note : This only is works in Ubuntu 12.10 or later - For earlier Ubuntu versions replace /run/shm with /dev/shm
Save and Reboot when done
tmpfs     /run/shm     tmpfs     defaults,noexec,nosuid     0     0
3. SSH Hardening - key based login, disable root login and change port.

The best way to secure SSH is to use public/private key based login. See SSH/OpenSSH/Keys
If you have to use password authentication, the easiest way to secure SSH is to disable root login and change the SSH port to something different than the standard port 22.
Before disabling the root login create a new SSH user and make sure the user belongs to the admin group (see step 4. below regarding the admin group).
if you change the SSH port keep the port number below 1024 as these are priviledged ports that can only be opened by root or processes running as root.
If you change the SSH port also open the new port you have chosen on the firewall and close port 22.
Open a Terminal Window and enter :
sudo vi /etc/ssh/sshd_config
Change or add the following and save.
Port <ENTER YOUR PORT>
Protocol 2
PermitRootLogin no
DebianBanner no
Restart SSH server, open a Terminal Window and enter :
sudo service ssh restart
4. Apache SSL Hardening - disable SSL v2/v3 support.

The SSL v2/v3 protocol has been proven to be insecure.
We will disable Apache support for the protocol and force the use of the newer protocols.
Open a Terminal Window and enter :
sudo vi /etc/apache2/mods-available/ssl.conf
Change this line from :
SSLProtocol all -SSLv3
To the following and save.
SSLProtocol all -SSLv2 -SSLv3
Restart the Apache server, open a Terminal Window and enter :
sudo service apache2 restart
5. Protect su by limiting access only to admin group.

To limit the use of su by admin users only we need to create an admin group, then add users and limit the use of su to the admin group.
Add a admin group to the system and add your own admin username to the group by replacing <YOUR ADMIN USERNAME> below with your admin username.
Open a terminal window and enter:
sudo groupadd admin
sudo usermod -a -G admin <YOUR ADMIN USERNAME>
sudo dpkg-statoverride --update --add root admin 4750 /bin/su
6. Harden network with sysctl settings.

The /etc/sysctl.conf file contain all the sysctl settings.
Prevent source routing of incoming packets and log malformed IP's enter the following in a terminal window:
sudo vi /etc/sysctl.conf
Edit the /etc/sysctl.conf file and un-comment or add the following lines :
# IP Spoofing protection
net.ipv4.conf.all.rp_filter = 1
net.ipv4.conf.default.rp_filter = 1

# Ignore ICMP broadcast requests
net.ipv4.icmp_echo_ignore_broadcasts = 1

# Disable source packet routing
net.ipv4.conf.all.accept_source_route = 0
net.ipv6.conf.all.accept_source_route = 0
net.ipv4.conf.default.accept_source_route = 0
net.ipv6.conf.default.accept_source_route = 0

# Ignore send redirects
net.ipv4.conf.all.send_redirects = 0
net.ipv4.conf.default.send_redirects = 0

# Block SYN attacks
net.ipv4.tcp_syncookies = 1
net.ipv4.tcp_max_syn_backlog = 2048
net.ipv4.tcp_synack_retries = 2
net.ipv4.tcp_syn_retries = 5

# Log Martians
net.ipv4.conf.all.log_martians = 1
net.ipv4.icmp_ignore_bogus_error_responses = 1

# Ignore ICMP redirects
net.ipv4.conf.all.accept_redirects = 0
net.ipv6.conf.all.accept_redirects = 0
net.ipv4.conf.default.accept_redirects = 0
net.ipv6.conf.default.accept_redirects = 0

# Ignore Directed pings
net.ipv4.icmp_echo_ignore_all = 1
To reload sysctl with the latest changes, enter:
sudo sysctl -p
7. Disable Open DNS Recursion and Remove Version Info  - BIND DNS Server.

Open a Terminal and enter the following :
sudo vi /etc/bind/named.conf.options
Add the following to the Options section :
recursion no;
version "Not Disclosed";
Restart BIND DNS server. Open a Terminal and enter the following :
sudo service bind9 restart
8. Prevent IP Spoofing.

Open a Terminal and enter the following :
sudo vi /etc/host.conf
Add or edit the following lines :
order bind,hosts
nospoof on
9. Harden PHP for security.

Edit the php.ini file :
sudo vi /etc/php5/apache2/php.ini
Add or edit the following lines an save :
disable_functions = exec,system,shell_exec,passthru
register_globals = Off
expose_php = Off
display_errors = Off
track_errors = Off
html_errors = Off
magic_quotes_gpc = Off
mail.add_x_header = Off
session.name = NEWSESSID
Restart Apache server. Open a Terminal and enter the following :
sudo service apache2 restart
10. Restrict Apache Information Leakage.

Edit the Apache2 configuration security file :
sudo vi /etc/apache2/conf-available/security.conf
Add or edit the following lines and save :
ServerTokens Prod
ServerSignature Off
TraceEnable Off
Header unset ETag
Header always unset X-Powered-By
FileETag None
Restart Apache server. Open a Terminal and enter the following :
sudo service apache2 restart
11. Web Application Firewall - ModSecurity.

See : How to install apache2 mod_security and mod_evasive on Ubuntu 12.04 LTS server
12. Protect from DDOS (Denial of Service) attacks - ModEvasive

See : How to install apache2 mod_security and mod_evasive on Ubuntu 12.04 LTS server
13. Scan logs and ban suspicious hosts - DenyHosts and Fail2Ban.

DenyHosts is a python program that automatically blocks SSH attacks by adding entries to /etc/hosts.deny. DenyHosts will also inform Linux administrators about offending hosts, attacked users and suspicious logins.
Open a Terminal and enter the following :
sudo apt-get install denyhosts
After installation edit the configuration file /etc/denyhosts.conf  and change the email, and other settings as required.
To edit the admin email settings open a terminal window and enter:
sudo vi /etc/denyhosts.conf
Change the following values as required on your server :
ADMIN_EMAIL = root@localhost
SMTP_HOST = localhost
SMTP_PORT = 25
#SMTP_USERNAME=foo
#SMTP_PASSWORD=bar
SMTP_FROM = DenyHosts nobody@localhost
#SYSLOG_REPORT=YES
Fail2ban is more advanced than DenyHosts as it extends the log monitoring to other services including SSH, Apache, Courier, FTP, and more.
Fail2ban scans log files and bans IPs that show the malicious signs -- too many password failures, seeking for exploits, etc.
Generally Fail2Ban then used to update firewall rules to reject the IP addresses for a specified amount of time, although any arbitrary other action could also be configured.
Out of the box Fail2Ban comes with filters for various services (apache, courier, ftp, ssh, etc).
Open a Terminal and enter the following :
sudo apt-get install fail2ban
After installation edit the configuration file /etc/fail2ban/jail.local  and create the filter rules as required.
To edit the settings open a terminal window and enter:
sudo vi /etc/fail2ban/jail.conf
Activate all the services you would like fail2ban to monitor by changing enabled = false to enabled = true
For example if you would like to enable the SSH monitoring and banning jail, find the line below and change enabled from false to true. Thats it.
[sshd]

enabled  = true
port     = ssh
filter   = sshd
logpath  = /var/log/auth.log
maxretry = 3
If you have selected a non-standard SSH port in step 3 then you need to change the port setting in fail2ban from ssh which by default is port 22, to your new port number, for example if you have chosen 1234 then port = 1234
[sshd]

enabled  = true
port     = <ENTER YOUR SSH PORT NUMBER HERE>
filter   = sshd
logpath  = /var/log/auth.log
maxretry = 3
If you would like to receive emails from Fail2Ban if hosts are banned change the following line to your email address.
destemail = root@localhost
and change the following line from :
action = %(action_)s
to:
action = %(action_mwl)s
You can also create rule filters for the various services that you would like fail2ban to monitor that is not supplied by default.
sudo vi /etc/fail2ban/jail.local
Good instructions on how to configure fail2ban and create the various filters can be found on HowtoForge - click here for an example
When done with the configuration of Fail2Ban restart the service with :
sudo service fail2ban restart
You can also check the status with.
sudo fail2ban-client status
14. Intrusion Detection - PSAD.

Cipherdyne PSAD is a collection of three lightweight system daemons that run on Linux machines and analyze iptables log messages to detect port scans and other suspicious traffic.
To install the latest version from the source files follow these instruction : How to install PSAD Intrusion Detection on Ubuntu 12.04 LTS server
OR install the older version from the Ubuntu software repositories, open a Terminal and enter the following :
sudo apt-get install psad
Then for basic configuration see How to install PSAD Intrusion Detection on Ubuntu 12.04 LTS server and follow from step 2:
15. Check for rootkits - RKHunter and CHKRootKit.

Both RKHunter and CHKRootkit basically do the same thing - check your system for rootkits. No harm in using both.
Open a Terminal and enter the following :
sudo apt-get install rkhunter chkrootkit
To run chkrootkit open a terminal window and enter :
sudo chkrootkit
To update and run RKHunter. Open a Terminal and enter the following :
sudo rkhunter --update
sudo rkhunter --propupd
sudo rkhunter --check
16. Scan open ports - Nmap.

Nmap ("Network Mapper") is a free and open source utility for network discovery and security auditing.
Open a Terminal and enter the following :
sudo apt-get install nmap
Scan your system for open ports with :
nmap -v -sT localhost
SYN scanning with the following :
sudo nmap -v -sS localhost
17. Analyse system LOG files - LogWatch.

Logwatch is a customizable log analysis system. Logwatch parses through your system's logs and creates a report analyzing areas that you specify. Logwatch is easy to use and will work right out of the package on most systems.
Open a Terminal and enter the following :
sudo apt-get install logwatch libdate-manip-perl
To view logwatch output use less :
sudo logwatch | less
To email a logwatch report for the past 7 days to an email address, enter the following and replace [email protected] with the required email. :
sudo logwatch --mailto [email protected] --output mail --format html --range 'between -7 days and today'
18. Apparmor - Application Armor.

More information can be found here. Ubuntu Server Guide - Apparmor
It is installed by default since Ubuntu 7.04.
Open a Terminal and enter the following :
sudo apt-get install apparmor apparmor-profiles
Check to see if things are running :
sudo apparmor_status
19. Audit your system security - Tiger and Tripwire.

Tiger is a security tool that can be use both as a security audit and intrusion detection system.
Tripwire is a host-based intrusion detection system (HIDS) that checks file and folder integrity.
Open a Terminal and enter the following :
sudo apt-get install tiger tripwire
To setup Tripwire good installation guides can be found on Digital Ocean here and on Unixmen here
To run tiger enter :
sudo tiger
All Tiger output can be found in the /var/log/tiger
To view the tiger security reports, open a Terminal and enter the following :
sudo less /var/log/tiger/security.report.*

##############################################
# Log Analysis with Linux command-line tools #
##############################################
- The following command line executables are found in the Mac as well as most Linux Distributions.

cat –  prints the content of a file in the terminal window
grep – searches and filters based on patterns
awk –  can sort each row into fields and display only what is needed
sed –  performs find and replace functions
sort – arranges output in an order
uniq – compares adjacent lines and can report, filter or provide a count of duplicates



###############
# Apache Logs #
###############

Reference:
http://www.the-art-of-web.com/system/logs/

wget https://s3.amazonaws.com/SecureNinja/Python/access_log


- You want to list all user agents ordered by the number of times they appear (descending order):

awk -F\" '{print $6}' access_log | sort | uniq -c | sort -fr



- Using the default separator which is any white-space (spaces or tabs) we get the following:

awk '{print $1}' access_log         # ip address (%h)
awk '{print $2}' access_log         # RFC 1413 identity (%l)
awk '{print $3}' access_log         # userid (%u)
awk '{print $4,5}' access_log       # date/time (%t)
awk '{print $9}' access_log         # status code (%>s)
awk '{print $10}' access_log        # size (%b)

- You might notice that we've missed out some items. To get to them we need to set the delimiter to the " character which changes the way the lines are 'exploded' and allows the following:

awk -F\" '{print $2}' access_log    # request line (%r)
awk -F\" '{print $4}' access_log    # referer
awk -F\" '{print $6}' access_log    # user agent


awk -F\" '{print $6}' access_log \
  | sed 's/(\([^;]\+; [^;]\+\)[^)]*)/(\1)/' \
  | sort | uniq -c | sort -fr


- The next step is to start filtering the output so you can narrow down on a certain page or referer. Would you like to know which pages Google has been requesting from your site?

awk -F\" '($6 ~ /Googlebot/){print $2}' access_log | awk '{print $2}'
Or who's been looking at your guestbook?

awk -F\" '($2 ~ /guestbook\.html/){print $6}' access_log


Reference:
https://blog.nexcess.net/2011/01/21/one-liners-for-apache-log-files/

# top 20 URLs from the last 5000 hits
tail -5000 ./access_log | awk '{print $7}' | sort | uniq -c | sort -rn | head -20
tail -5000 ./access_log | awk '{freq[$7]++} END {for (x in freq) {print freq[x], x}}' | sort -rn | head -20

# top 20 URLS excluding POST data from the last 5000 hits
tail -5000 ./access_log | awk -F"[ ?]" '{print $7}' | sort | uniq -c | sort -rn | head -20
tail -5000 ./access_log | awk -F"[ ?]" '{freq[$7]++} END {for (x in freq) {print freq[x], x}}' | sort -rn | head -20

# top 20 IPs from the last 5000 hits
tail -5000 ./access_log | awk '{print $1}' | sort | uniq -c | sort -rn | head -20
tail -5000 ./access_log | awk '{freq[$1]++} END {for (x in freq) {print freq[x], x}}' | sort -rn | head -20

# top 20 URLs requested from a certain ip from the last 5000 hits
IP=1.2.3.4; tail -5000 ./access_log | grep $IP | awk '{print $7}' | sort | uniq -c | sort -rn | head -20
IP=1.2.3.4; tail -5000 ./access_log | awk -v ip=$IP ' $1 ~ ip {freq[$7]++} END {for (x in freq) {print freq[x], x}}' | sort -rn | head -20

# top 20 URLS requested from a certain ip excluding, excluding POST data, from the last 5000 hits
IP=1.2.3.4; tail -5000 ./access_log | fgrep $IP | awk -F "[ ?]" '{print $7}' | sort | uniq -c | sort -rn | head -20
IP=1.2.3.4; tail -5000 ./access_log | awk -F"[ ?]" -v ip=$IP ' $1 ~ ip {freq[$7]++} END {for (x in freq) {print freq[x], x}}' | sort -rn | head -20

# top 20 referrers from the last 5000 hits
tail -5000 ./access_log | awk '{print $11}' | tr -d '"' | sort | uniq -c | sort -rn | head -20
tail -5000 ./access_log | awk '{freq[$11]++} END {for (x in freq) {print freq[x], x}}' | tr -d '"' | sort -rn | head -20

# top 20 user agents from the last 5000 hits
tail -5000 ./access_log | cut -d\  -f12- | sort | uniq -c | sort -rn | head -20

# sum of data (in MB) transferred in the last 5000 hits
tail -5000 ./access_log | awk '{sum+=$10} END {print sum/1048576}'


##############
# Cisco Logs #
##############

wget https://s3.amazonaws.com/StrategicSec-Files/LogAnalysis/cisco.log


AWK Basics
----------
- To quickly demonstrate the print feature in awk, we can instruct it to show only the 5th word of each line. Here we will print $5. Only the last 4 lines are being shown for brevity.

cat cisco.log | awk '{print $5}' | tail -n 4




- Looking at a large file would still produce a large amount of output. A more useful thing to do might be to output every entry found in “$5”, group them together, count them, then sort them from the greatest to least number of occurrences. This can be done by piping the output through “sort“, using “uniq -c” to count the like entries, then using “sort -rn” to sort it in reverse order.

cat cisco.log | awk '{print $5}'| sort | uniq -c | sort -rn




- While that’s sort of cool, it is obvious that we have some garbage in our output. Evidently we have a few lines that aren’t conforming to the output we expect to see in $5. We can insert grep to filter the file prior to feeding it to awk. This insures that we are at least looking at lines of text that contain “facility-level-mnemonic”.

cat cisco.log | grep %[a-zA-Z]*-[0-9]-[a-zA-Z]* | awk '{print $5}' | sort | uniq -c | sort -rn





- Now that the output is cleaned up a bit, it is a good time to investigate some of the entries that appear most often. One way to see all occurrences is to use grep.

cat cisco.log | grep %LINEPROTO-5-UPDOWN:

cat cisco.log | grep %LINEPROTO-5-UPDOWN:| awk '{print $10}' | sort | uniq -c | sort -rn

cat cisco.log | grep %LINEPROTO-5-UPDOWN:| sed 's/,//g' | awk '{print $10}' | sort | uniq -c | sort -rn

cat cisco.log | grep %LINEPROTO-5-UPDOWN:| sed 's/,//g' | awk '{print $10 " changed to " $14}' | sort | uniq -c | sort -rn









##############################
# Linux For InfoSec Homework #
##############################
In order to receive your certificate of attendance you must complete the all of the quizzes on the http://linuxsurvival.com/linux-tutorial-introduction/ website.


Submit the results via email in an MS Word document with (naming convention example: YourFirstName-YourLastName-Linux-For-InfoSec-Homework.docx)




##############################
# Linux For InfoSe Challenge #
##############################

In order to receive your certificate of proficiency you must complete all of the tasks covered in the Linux For InfoSec pastebin (http://pastebin.com/b5SxBRf6).

Submit the results via email in an MS Word document with (naming convention example: YourFirstName-YourLastName-Linux-For-InfoSec-Challenge.docx)




IMPORTANT NOTE:
Your homework/challenge must be submitted via email to both (joe-at-strategicsec-.-com and kasheia-at-strategicsec-.-com) by Sunday October 16th at midnight EST.


#########################################################################
# What kind of Linux am I on and how can I find out? 			        #
# Great reference: 							                            #
# https://blog.g0tmi1k.com/2011/08/basic-linux-privilege-escalation/ 	#
#########################################################################
- What’s the distribution type? What version?
-------------------------------------------
cat /etc/issue
cat /etc/*-release
cat /etc/lsb-release      		# Debian based
cat /etc/redhat-release   		# Redhat based



- What’s the kernel version? Is it 64-bit?
-------------------------------------------
cat /proc/version
uname -a
uname -mrs
rpm -q kernel
dmesg | grep Linux
ls /boot | grep vmlinuz-



- What can be learnt from the environmental variables?
----------------------------------------------------
cat /etc/profile
cat /etc/bashrc
cat ~/.bash_profile
cat ~/.bashrc
cat ~/.bash_logout
env
set


- What services are running? Which service has which user privilege?
------------------------------------------------------------------
ps aux
ps -ef
top
cat /etc/services


- Which service(s) are been running by root? Of these services, which are vulnerable - it’s worth a double check!
---------------------------------------------------------------------------------------------------------------
ps aux | grep root
ps -ef | grep root



- What applications are installed? What version are they? Are they currently running?
------------------------------------------------------------------------------------
ls -alh /usr/bin/
ls -alh /sbin/
dpkg -l
rpm -qa
ls -alh /var/cache/apt/archivesO
ls -alh /var/cache/yum/


- Any of the service(s) settings misconfigured? Are any (vulnerable) plugins attached?
------------------------------------------------------------------------------------
cat /etc/syslog.conf
cat /etc/chttp.conf
cat /etc/lighttpd.conf
cat /etc/cups/cupsd.conf
cat /etc/inetd.conf
cat /etc/apache2/apache2.conf
cat /etc/my.conf
cat /etc/httpd/conf/httpd.conf
cat /opt/lampp/etc/httpd.conf
ls -aRl /etc/ | awk '$1 ~ /^.*r.*/



- What jobs are scheduled?
------------------------
crontab -l
ls -alh /var/spool/cron
ls -al /etc/ | grep cron
ls -al /etc/cron*
cat /etc/cron*
cat /etc/at.allow
cat /etc/at.deny
cat /etc/cron.allow
cat /etc/cron.deny
cat /etc/crontab
cat /etc/anacrontab
cat /var/spool/cron/crontabs/root


- Any plain text usernames and/or passwords?
------------------------------------------
grep -i user [filename]
grep -i pass [filename]
grep -C 5 "password" [filename]
find . -name "*.php" -print0 | xargs -0 grep -i -n "var $password"   		# Search for Joomla passwords


- What NIC(s) does the system have? Is it connected to another network?
---------------------------------------------------------------------
/sbin/ifconfig -a
cat /etc/network/interfaces
cat /etc/sysconfig/network


- What are the network configuration settings? What can you find out about this network? DHCP server? DNS server? Gateway?
------------------------------------------------------------------------------------------------------------------------
cat /etc/resolv.conf
cat /etc/sysconfig/network
cat /etc/networks
iptables -L
hostname
dnsdomainname

- What other users & hosts are communicating with the system?
-----------------------------------------------------------
lsof -i
lsof -i :80
grep 80 /etc/services
netstat -antup
netstat -antpx
netstat -tulpn
chkconfig --list
chkconfig --list | grep 3:on
last
w



- Whats cached? IP and/or MAC addresses
-------------------------------------
arp -e
route
/sbin/route -nee


- Who are you? Who is logged in? Who has been logged in? Who else is there? Who can do what?
------------------------------------------------------------------------------------------
id
who
w
last
cat /etc/passwd | cut -d:    # List of users
grep -v -E "^#" /etc/passwd | awk -F: '$3 == 0 { print $1}'   # List of super users
awk -F: '($3 == "0") {print}' /etc/passwd   # List of super users
cat /etc/sudoers
sudo -l



- What sensitive files can be found?
----------------------------------
cat /etc/passwd
cat /etc/group
cat /etc/shadow
ls -alh /var/mail/



- Anything “interesting” in the home directorie(s)? If it’s possible to access
----------------------------------------------------------------------------
ls -ahlR /root/
ls -ahlR /home/


- Are there any passwords in; scripts, databases, configuration files or log files? Default paths and locations for passwords
---------------------------------------------------------------------------------------------------------------------------
cat /var/apache2/config.inc
cat /var/lib/mysql/mysql/user.MYD
cat /root/anaconda-ks.cfg


- What has the user being doing? Is there any password in plain text? What have they been edting?
-----------------------------------------------------------------------------------------------
cat ~/.bash_history
cat ~/.nano_history
cat ~/.atftp_history
cat ~/.mysql_history
cat ~/.php_history



- What user information can be found?
-----------------------------------
cat ~/.bashrc
cat ~/.profile
cat /var/mail/root
cat /var/spool/mail/root


- Can private-key information be found?
-------------------------------------
cat ~/.ssh/authorized_keys
cat ~/.ssh/identity.pub
cat ~/.ssh/identity
cat ~/.ssh/id_rsa.pub
cat ~/.ssh/id_rsa
cat ~/.ssh/id_dsa.pub
cat ~/.ssh/id_dsa
cat /etc/ssh/ssh_config
cat /etc/ssh/sshd_config
cat /etc/ssh/ssh_host_dsa_key.pub
cat /etc/ssh/ssh_host_dsa_key
cat /etc/ssh/ssh_host_rsa_key.pub
cat /etc/ssh/ssh_host_rsa_key
cat /etc/ssh/ssh_host_key.pub
cat /etc/ssh/ssh_host_key


- Any settings/files (hidden) on website? Any settings file with database information?
------------------------------------------------------------------------------------
ls -alhR /var/www/
ls -alhR /srv/www/htdocs/
ls -alhR /usr/local/www/apache22/data/
ls -alhR /opt/lampp/htdocs/
ls -alhR /var/www/html/


- Is there anything in the log file(s) (Could help with “Local File Includes”!)
-----------------------------------------------------------------------------
cat /etc/httpd/logs/access_log
cat /etc/httpd/logs/access.log
cat /etc/httpd/logs/error_log
cat /etc/httpd/logs/error.log
cat /var/log/apache2/access_log
cat /var/log/apache2/access.log
cat /var/log/apache2/error_log
cat /var/log/apache2/error.log
cat /var/log/apache/access_log
cat /var/log/apache/access.log
cat /var/log/auth.log
cat /var/log/chttp.log
cat /var/log/cups/error_log
cat /var/log/dpkg.log
cat /var/log/faillog
cat /var/log/httpd/access_log
cat /var/log/httpd/access.log
cat /var/log/httpd/error_log
cat /var/log/httpd/error.log
cat /var/log/lastlog
cat /var/log/lighttpd/access.log
cat /var/log/lighttpd/error.log
cat /var/log/lighttpd/lighttpd.access.log
cat /var/log/lighttpd/lighttpd.error.log
cat /var/log/messages
cat /var/log/secure
cat /var/log/syslog
cat /var/log/wtmp
cat /var/log/xferlog
cat /var/log/yum.log
cat /var/run/utmp
cat /var/webmin/miniserv.log
cat /var/www/logs/access_log
cat /var/www/logs/access.log
ls -alh /var/lib/dhcp3/
ls -alh /var/log/postgresql/
ls -alh /var/log/proftpd/
ls -alh /var/log/samba/

- Note: auth.log, boot, btmp, daemon.log, debug, dmesg, kern.log, mail.info, mail.log, mail.warn, messages, syslog, udev, wtmp