How To: Secure and Optimize your VPS

[Raptile]

Hi, in this thread you will be learning a few tips that help on securing your VPS and optimizing it, you don't have to execute all of the commands, only some which you might find useful for your website.
This tutorial is not fully written by me!
I hope you will enjoy reading this tutorial and find it informative, if you have any queries, issues, questions, on executing these commands or anything related to this post then don't hesitate to reply here, me and other members will be glad to help you.

=========================================
Checking for formmail
=========================================

Form mail is used by hackers to send out spam email, by relay and injection methods. If you are using matts script or a version of it, you may be in jeopardy.


Command to find pesky form mails:

 find / -name "[Ff]orm[mM]ai*"

CGIemail is also a security risk:

 find / -name "[Cc]giemai*"

Command to disable form mails:

 chmod a-rwx /path/to/filename

(a-rwx translates to all types, no read, write or execute permissions).

(this disables all form mail)

If a client or someone on your vps installs form mail, you will have to let them know you are disabling their script and give them an alternative.


=========================================
Root kit checker -

http://www.chkrootkit.org/

=========================================

Check for root kits and even set a root kit on a cron job. This will show you if anyone has compromised your root. Always update chrootkit to get the latest root kit checker. Hackers and spammers will try to find insecure upload forms on your box and then with injection methods, try to upload the root kit on your server. If he can run it, it will modify *alot* of files, possibly causing you to have to reinstall.


To install chrootkit, SSH into server and login as root.
At command prompt type:

cd /root/
wget ftp://ftp.pangeia.com .br/pub/seg/pac/chkrootkit.tar.gz
tar xvzf chkrootkit.tar.gz 
cd chkrootkit-0.44
make sense

To run chkrootkit

At command prompt type: 
/root/chkrootkit-0.44/chkrootkit

Make sure you run it on a regular basis, perhaps including it in a cron job.

Execution

I use these three commands the most.

./chkrootkit
./chkrootkit -q
./chkrootkit -x | more

=========================================
Install a root breach DETECTOR and EMAIL WARNING
=========================================

If someone does happen to get root, be warned quickly by installing a detector and warning at your box. You will at least get the hackers/spammers ip address and be warned someone is in there.


Server e-mail everytime someone logs in as root

To have the server e-mail you everytime someone logs in as root, SSH into server and login as root.


At command prompt type:

 pico .bash_profile

Scroll down to the end of the file and add the following line:

 echo 'ALERT - Root Shell Access on:' `date` `who` | mail -s "Alert: Root Access from `who | awk '{print $6}'`" your@email.com

Save and exit.


Set an SSH Legal Message

To an SSH legal message, SSH into server and login as root.

At command prompt type:

 pico /etc/motd

Enter your message, save and exit.
Note: I use the following message...

ALERT! You are entering a secured area! Your IP and login information
have been recorded. System administration has been notified.
This system is restricted to authorized access only. All activities on
this system are recorded and logged. Unauthorized access will be fully
investigated and reported to the appropriate law enforcement agencies.

=========================================
Web Host manager and CPANEL mods.
=========================================

These are items inside of WHM/Cpanel that should be changed to secure your server.

Goto Server Setup =>> Tweak Settings
Check the following items...

Under Domains
Prevent users from parking/adding on common internet domains.

(ie hotmail.com, aol.com)

Under Mail
Attempt to prevent pop3 connection floods

 Default catch-all/default address behavior for new accounts - blackhole

(according to some people- set this to FAIL, which is what I am going to do to reduce server load)

Under System
Use jailshell as the default shell for all new accounts and modified accounts

Goto Server Setup =>> Tweak Security
Enable php open_basedir Protection
Enable mod_userdir Protection
Disabled Compilers for unprivileged users.

Goto Server Setup =>> Manage Wheel Group Users
Remove all users except for root and your main account from the wheel group.

Goto Server Setup =>> Shell Fork Bomb Protection
Enable Shell Fork Bomb/Memory Protection

When setting up Feature Limits for resellers in Resellers =>> Reseller Center, under Privileges always disable Allow Creation of Packages with Shell Access and enable Never allow creation of accounts with shell access; under Root Access disable All Features.

Goto Service Configuration =>> FTP Configuration
Disable Anonymous FTP

Goto Account Functions =>> Manage Shell Access
Disable Shell Access for all users (except yourself)

Goto Mysql =>> MySQL Root Password
Change root password for MySQL

Goto Security and run Quick Security Scan and Scan for Trojan Horses often. The following and similar items are not Trojans:

  
/sbin/depmod
/sbin/insmod
/sbin/insmod.static
/sbin/modinfo
/sbin/modprobe
/sbin/rmmod

=========================================
More Security Measures
=========================================

These are measures that can be taken to secure your server, with SSH access.

Update OS, Apache and CPanel to the latest stable versions.
This can be done from WHM/CPanel.


Restrict SSH Access
To restrict and secure SSH access, bind sshd to a single IP that is different than the main IP to the server, and on a different port than port 22.

SSH into server and login as root.
Note: You can download Putty by Clicking Here:

 http://www.chiark.greenend.org.uk/~sgtatham/putty/download.html

.
It's a clean running application that will not require installation on Windows-boxes.

At command prompt type:

 pico /etc/ssh/sshd_config

Scroll down to the section of the file that looks like this:
#Port 22
#Protocol 2, 1
#ListenAddress 0.0.0.0
#ListenAddress ::

Uncomment and change
#Port 22
to look like
Port 5678 (choose your own 4 to 5 digit port number (49151 is the highest port number AND do not use 5678)

Uncomment and change
#Protocol 2, 1
to look like
Protocol 2

Uncomment and change
#ListenAddress 0.0.0.0
to look like
ListenAddress 123.123.123.15 (use one of your own IP Addresses that has been assigned to your server)

Note 1: If you would like to disable direct Root Login, scroll down until you find
#PermitRootLogin yes
and uncomment it and make it look like
PermitRootLogin no

Save by pressing Ctrl o on your keyboard, and then exit by pressing Ctrl x on your keyboard.


Note 2: You can also create a custome nameserver specifically for your new SSH IP address. Just create one called something like ssh.xyz.com or whatever. Be sure to add an A address to your zone file for the new nameserver.

Now restart SSH
At command prompt type:

 /etc/rc.d/init.d/sshd restart

Exit out of SSH, and then re-login to SSH using the new IP or nameserver, and the new port.

Note: If you should have any problems, just Telnet into your server, fix the problem, then SSH in again. Telnet is a very unsecure protocol, so change your root password after you use it.

After SSH has been redirected, disable telnet.

Disable Telnet
To disable telnet, SSH into server and login as root.
At command prompt type:

pico -w /etc/xinetd.d/telnet

change disable = no to disable = yes
Save and Exit
At command prompt type:

/etc/init.d/xinetd restart

Disable Shell Accounts
To disable any shell accounts hosted on your server SSH into server and login as root.
At command prompt type: locate shell.php
Also check for:

locate irc
locate eggdrop
locate bnc
locate BNC
locate ptlink
locate BitchX
locate guardservices
locate psyBNC
locate .rhosts 

Note: There will be several listings that will be OS/CPanel related. Examples are

/home/cpapachebuild/buildapache/php-4.3.1/ext/ircg
/usr/local/cpanel/etc/sym/eggdrop.sym
/usr/local/cpanel/etc/sym/bnc.sym
/usr/local/cpanel/etc/sym/psyBNC.sym
/usr/local/cpanel/etc/sym/ptlink.sym
/usr/lib/libncurses.so
/usr/lib/libncurses.a
etc.

Disable identification output for Apache

(do this to hide version numbers from potentional hackers)

To disable the version output for proftp, SSH into server and login as root.
At command prompt type: pico /etc/httpd/conf/httpd.conf

Scroll (way) down and change the following line to
ServerSignature Off

Restart Apache
At command prompt type:

/etc/rc.d/init.d/httpd restart

=========================================
Install BFD (Brute Force Detection - optional)
=========================================

To install BFD, SSH into server and login as root.

At command prompt type:

cd /root/
wget http://www.rfxnetworks.com/downloads/bfd-current.tar.gz
tar -xvzf bfd-current.tar.gz
cd bfd-0.4
./install.sh

After BFD has been installed, you need to edit the configuration file.

At command prompt type:

 pico /usr/local/bfd/conf.bfd

Under Enable brute force hack attempt alerts:
Find

ALERT_USR="0" 
and change it to 
ALERT_USR="1"

Find

EMAIL_USR="root" 
and change it to 
EMAIL_USR="your@email.com"

Save the changes then exit.

To start BFD

At command prompt type:

 /usr/local/sbin/bfd -s

Modify LogWatch
Logwatch is a customizable log analysis system. It parses through your system's logs for a given period of time and creates a report analyzing areas that you specify, in as much detail as you require. Logwatch is already installed on most CPanel servers.

To modify LogWatch, SSH into server and login as root.

At command prompt type:

 pico -w /etc/log.d/conf/logwatch.conf

Scroll down to

MailTo = root
and change to
Mailto = your@email.com

Note: Set the e-mail address to an offsite account incase you get hacked.

Now scroll down to

Detail = Low
Change that to Medium, or High...
Detail = 5 or Detail = 10

Note: High will give you more detailed logs with all actions.

Save and exit.

A number of suggestions to improve system security. Some of this is specific to CPanel, but much can be applied to most Linux systems.
--------------------------------------------------
Use The Latest Software
Keep the OS and 3rd party software up to date. Always!
CPanel itself can be updated from the root WHM.
--------------------------------------------------
Change Passwords
Change the root passwords at least once a month and try to make them hard to guess. Yes it's a pain to have to keep remembering them, but it's better than being hacked.

--------------------------------------------------
Set Up A More Secure SSH Environment As described here.
--------------------------------------------------
Disable Telnet

1. Type: pico -w /etc/xinetd.d/telnet
2. Change the disable = no line to disable = yes.
3. Hit CTRL+X press y and then enter to save the file.
4. Restart xinted with: /etc/rc.d/init.d/xinetd restart

Also, add the following line to /etc/deny.hosts to flag Telnet access attempts as 'emergency' messages:

 in.telnetd : ALL : severity emerg

--------------------------------------------------
Disable Unnecessary Ports (optional)
First backup the file that contains your list of ports with:

 cp /etc/services /etc/services.original

Now configure /etc/services so that it only has the ports you need in it. This will match the ports enabled in your firewall.
On a typical CPanel system it would look something like this:

<?php
tcpmux 1/tcp # TCP port service multiplexer 
echo 7/tcp 
echo 7/udp 
ftp-data 20/tcp 
ftp 21/tcp 
ssh 22/tcp # SSH Remote Login Protocol 
smtp 25/tcp mail 
domain 53/tcp # name-domain server 
domain 53/udp 
http 80/tcp www www-http # WorldWideWeb HTTP 
pop3 110/tcp pop-3 # POP version 3 
imap 143/tcp imap2 # Interim Mail Access Proto v2 
https 443/tcp # MCom 
smtps 465/tcp # SMTP over SSL (TLS) 
syslog 514/udp 
rndc 953/tcp # rndc control sockets (BIND 9) 
rndc 953/udp # rndc control sockets (BIND 9) 
imaps 993/tcp # IMAP over SSL 
pop3s 995/tcp # POP-3 over SSL 
cpanel 2082/tcp 
cpanels 2083/tcp 
whm 2086/tcp 
whms 2087/tcp 
webmail 2095/tcp 
webmails 2096/tcp 
mysql 3306/tcp # MySQL 
?>

Additional ports are controlled by /etc/rpc. These aren't generally needed, so get shot of that file with: mv /etc/rpc /etc/rpc-moved
--------------------------------------------------
Watch The Logs
Install something like logwatch to keep an eye on your system logs. This will extract anything 'interesting' from the logs and e-mail to you on a daily basis.
Logwatch can be found at:

http://www.logwatch.org

--------------------------------------------------
Avoid CPanel Demo Mode
Switch it off via WHM Account Functions => Disable or Enable Demo Mode.
--------------------------------------------------
Jail All Users
Via WHM Account Functions => Manage Shell Access => Jail All Users.
Better still never allow shell access to anyone - no exceptions.
--------------------------------------------------
Immediate Notification Of Specific Attackers
If you need immediate notification of a specific attacker (TCPWrapped services only), add the following to /etc/hosts.deny

ALL : nnn.nnn.nnn.nnn : spawn /bin/ 'date' %c %d | mail -s"Access attempt by nnn.nnn.nnn.nnn on for hostname" notify@mydomain.com
Replacing nnn.nnn.nnn.nnn with the attacker's IP address.
Replacing hostname with your hostname.
Replacing notify@mydomain.com with your e-mail address.

This will deny access to the attacker and e-mail the sysadmin about the access attempt.
--------------------------------------------------
Check Open Ports
From time to time it's worth checking which ports are open to the outside world. This can be done with:
nmap -sT -O localhost
If nmap isn't installed, it can be selected from root WHM's Install an RPM option.
--------------------------------------------------
Set The MySQL Root Password
This can be done in CPanel from the root WHM Server Setup -> Set MySQL Root Password.
Make it different to your root password!
--------------------------------------------------
Tweak Security (CPanel)
From the root WHM, Server Setup -> Tweak Security, you will most likely want to enable:
- php open_basedir Tweak.
- SMTP tweak.
You may want to enable:
- mod_userdir Tweak. But that will disable domain preview.
--------------------------------------------------
Use SuExec (CPanel)
From root WHM, Server Setup -> Enable/Disable SuExec. This is CPanel's decription of what it does:
"suexec allows cgi scripts to run with the user's id. It will also make it easier to track which user has sent out an email. If suexec is not enabled, all cgi scripts will run as nobody. "
Even if you don't use phpsuexec (which often causes more problems), SuExec should be considered.
--------------------------------------------------
Use PHPSuExec (CPanel)
This needs to built into Apache (Software -> Update Apache from the root WHM) and does the same as SuExec but for PHP scripts.
Wisth PHPSuExec enabled, you users will have to make sure that all their PHP files have permissions no greater than 0755 and that their htaccess files contain no PHP directives.
--------------------------------------------------
Disable Compilers
This will prevent hackers from compiling worms, root kits and the like on your machine.
To disable them, do the following:

chmod 000 /usr/bin/perlcc 
chmod 000 /usr/bin/byacc 
chmod 000 /usr/bin/yacc 
chmod 000 /usr/bin/bcc 
chmod 000 /usr/bin/kgcc 
chmod 000 /usr/bin/cc 
chmod 000 /usr/bin/gcc 
chmod 000 /usr/bin/i386*cc
chmod 000 /usr/bin/*c++ 
chmod 000 /usr/bin/*g++ 
chmod 000 /usr/lib/bcc /usr/lib/bcc/bcc-cc1 
chmod 000 /usr/i386-glibc21-linux/lib/gcc-lib/i386-redhat-linux/2.96/cc1

You will need to enable them again when you need to perform system updates. To do this, run:

chmod 755 /usr/bin/perlcc 
chmod 755 /usr/bin/byacc 
chmod 755 /usr/bin/yacc 
chmod 755 /usr/bin/bcc 
chmod 755 /usr/bin/kgcc 
chmod 755 /usr/bin/cc 
chmod 755 /usr/bin/gcc 
chmod 755 /usr/bin/i386*cc
chmod 755 /usr/bin/*c++ 
chmod 755 /usr/bin/*g++ 
chmod 755 /usr/lib/bcc /usr/lib/bcc/bcc-cc1 
chmod 755 /usr/i386-glibc21-linux/lib/gcc-lib/i386-redhat-linux/2.96/cc1
 

--------------------------------------------------
Obfuscate The Apache Version Number

1. Type:

pico /etc/httpd/conf/httpd.conf

2. Change the line that begins ServerSignature to:

 ServerSignature Off

3. Add a line underneath that which reads:

 ServerTokens ProductOnly

4. Hit CTRL+X, they y, the enter to save the file.
5. Restart Apache with:

/etc/rc.d/init.d/httpd restart

----------------------
Common Commands i use:

System Information

who

List the users logged in on the machine. --

 rwho -a

List all users logged in on your network. The rwho service must be enabled for this command to work.

 finger user_name

System info about a user. Try: finger root last. This lists the users last logged-in on your system.

 history | more

Show the last (1000 or so) commands executed from the command line on the current account. The | more causes the display to stop after each screen fill.

pwd

Print working directory, i.e. display the name of your current directory on the screen.

hostname

uptime

Amount of time since the last reboot

ps

List the processes that are have been run by the current user.

 ps aux | more

List all the processes currently running, even those without the controlling terminal, together with the name of the user that owns each process.

top

Keep listing the currently running processes, sorted by cpu usage (top users first).

 uname -a

Info on your server.

  set|more

Show the current user environment.

 echo $PATH

Show the content of the environment variable PATH. This command can be used to show other environment variables as well. Use set to see the full environment.

 dmesg | less

Print kernel messages (the current content of the so-called kernel ring buffer). Press q to quit less. Use less /var/log/dmesg to see what dmesg dumped into the file right after bootup. - only works on dedciated systems

Processor commands:

kill PID

Force a process shutdown. First determine the PID of the process to kill using ps.

 killall -9 program_name

Kill program(s) by name.

 xkill

(in an xwindow terminal) Kill a GUI-based program with mouse. (Point with your mouse cursor at the window of the process you want to kill and click.)


[/SIZE]

=========================================
MySQL Optimization
=========================================

Here are my suggested settings for the my.cnf file. This should work well for a VPS with 256-512MB RAM.

[mysqld]
max_connections = 400
key_buffer = 16M
myisam_sort_buffer_size = 32M
join_buffer_size = 1M
read_buffer_size = 1M
sort_buffer_size = 2M
table_cache = 1024
thread_cache_size = 286
interactive_timeout = 25
wait_timeout = 1000
connect_timeout = 10
max_allowed_packet = 16M
max_connect_errors = 10
query_cache_limit = 1M
query_cache_size = 16M
query_cache_type = 1
tmp_table_size = 16M
skip-innodb
 
[mysqld_safe]
open_files_limit = 8192
 
[mysqldump]
quick
max_allowed_packet = 16M
 
[myisamchk]
key_buffer = 32M
sort_buffer = 32M
read_buffer = 16M
write_buffer = 16M

In order to make things even faster, you can customize these settings specifically for your VPSs' usage. There's a great howto on InterWorx's forum for this:

http://www.interworx.com/forums/showthread.php?p=2346

Lastly, I recommend installing mytop to help you monitor your usage...

wget http://dll.elix.us/mytop-1.4.tar.gz
tar -zxvf mytop-1.4.tar.gz
cd mytop-1.4
perl Makefile.PL
make
make test
make install

Once that's done, just enter in "mytop" .

PHP & Apache Optimization
I strongly recommend installing eAccelerator. There's an easy to follow howto here:

 http://forum.ev1servers.net/showthread.php?t=23574&highlight=eaccelerator

If you use the default cache dir for eAccelerator (/tmp/eaccelerator) make sure you check it reguarily and clean it every once and a while. (it can really get quite large from my experience)

For httpd.conf I suggest:

Timeout 200
KeepAlive On
maxKeepAliveRequests 100
KeepAliveTimeout 3
MinSpareServers 10
MaxSpareServers 20
StartServers 15
MaxClients 250
MaxRequestsPerChild 0
HostnameLookups Off

You can use ab to benchmark your Apache before and after you make changes.

ab -c 5 -n 20 somephpbasedsiteonyourserver.com/file.php

I suggest doing 2 or 3 tests like that to get an average.

If you want to check the Apache error log, try this -->

cat /usr/local/apache/logs/error_log

You can find the amount of connections to Apache with this command:

netstat -nt | grep :80 | wc -l

To find the amount of Apache processes use this command:

ps -A | grep httpd | wc -l

(this will show the process count)

ps -aux | grep httpd

(this will show the actual processes)

To find the amount of MySQL processes use this command:

ps -A | grep mysql | wc -l

(this will show the process count)

ps -aux | grep mysql

(this will show the actual processes)

Just simply using top (standard view) or top -c (will show the actual command being used and/or location of each process as opposed to just the name) can help you monitor your VPS usage very wel.

To see your disk space usage, try using this command:

 df -h

Mitigating (D)DOS
If you're being DDOS'd or DOS'd you can use this command:

netstat -ntu | awk '{print $5}' | cut -d: -f1 | sort | uniq -c | sort -n

That will help you see how many connections each IP address has in total to your server.

Spam Assassin
Spam Assassin can take up a lot of memory and make it really hard to host just a few sites on a VPS, but there is a way around this...

Login to WHM as root, scroll down to "cPanel 10.8.1-R15" (it may be slightly different depending on what version you are using) then goto "Addon Modules" and install "spamdconf". Once it's done, refresh the WHM page, scroll down to "Add-ons" on the nav bar and then click on 'Setup Spamd Startup Configuration". Set "Maximum Children" to "2". Then hit Submit. Wait a few seconds (15-30, but usually less) for exim to restart and you're done .

cPanel Tweak Setings
Login to WHM as root, and under "Server Configuration" on the nav bar hit "Tweak Settings".

Here are some suggested settings:
Default catch-all/default address behavior for new accounts. fail will generally save the most CPU time.
- Use "FAIL". If you already have some accounts setup not to use "FAIL" (by default it will not) then run this command to convert to FAIL from BLACKHOLE --> perl -pi -e "s/:blackhole:/:fail:/g;" /etc/valiases/*

Mailman
- Mailman tends to use a lot of resources, so if you don't need cpanel mailing lists then uncheck this.

Number of minutes between mail server queue runs (default is 60).:
- You may want to set this to 180 to reduce load.

Track the origin of messages sent though the mail server by adding the X-Source headers (exim 4.34+ required)
- This is just generally a good idea. So check this.

Analog Stats
- I find this useless, so uncheck this. If you want to delete the existing analog stats files just run this command --> rm -rf /home/*/tmp/analog/*

Awstats Reverse Dns Resolution
- Make sure this is unchecked, I find it pretty much useless for most users.

Awstats Stats
- You can check this if you need a robust stats software that integrates with cPanel, if you don't need it, then don't check it. *Note most hosting clients will want to use this. If you want to delete the existing awstats stats files just run this command --> rm -rf /home/*/tmp/awstats/*

Webalizer Stats
- Not many hosting clients will want to use this so, you can uncheck this to reduce load. If you want to delete the existing webalizer stats files just run this command --> rm -rf /home/*/tmp/webalizer/*

Delete each domain's access logs after stats run
- Make sure this is checked, otherwise disk space usage can really rack up!

Raptile Reviewed by Raptile on 2nd Oct 2011. How To: Secure and Optimize your VPS Hi, in this thread you will be learning a few tips that help on securing your VPS and optimizing it, you don't have to execute all of the commands, only some which you might find useful for your website. This tutorial is not fully written by me! I hope you will enjoy reading this tutorial and find it informative, if you have any queries, issues, questions, on executing these commands or anything related to this post then don't hesitate to reply here, me and other members will be glad to help Rating: 5

[Raptile]

Thread has been updated, enjoy.

[leonight]

awesome job

[Sponge Bob]

Wow nice stuff here.

Thanks

[Miguel]

The thread repeats itself more or less in the middle.
Thanks

[downote]

good job, reading on

[Raptile]

Enjoy..

[phreaker]

Awesome guide! Thank you very much

[kazuhiro]

Thank's for the guide. It's awesome. Very helpful

[Tele]

awesome bro, thanks a lot