Rootadminacc: /* Disabling the root user */

2013-03-07T13:19:33Z

Disabling the root user

← Older revision		Revision as of 14:19, 7 March 2013
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	Set this value:		Set this value:
	<pre>PermitRootLogin no</pre>		<pre>PermitRootLogin no</pre>
	~~Exit the file and type~~:
			Check sudo is actually installed:

			<pre>apt-get install sudo
			yum install sudo</pre>

	<pre>visudo</pre>		<pre>visudo</pre>
	Under User privilege specification (on Ubuntu) or Allow root to run any commands anywhere (on CentOS)		Under User privilege specification (on Ubuntu) or Allow root to run any commands anywhere (on CentOS)

Rootadminacc: /* Password Safety */

2013-02-22T14:42:40Z

Password Safety

← Older revision		Revision as of 15:42, 22 February 2013
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	http://www.google.co.uk/goodtoknow/online-safety/passwords		http://www.google.co.uk/goodtoknow/online-safety/passwords

			Unix password cracking (rough article): http://www.governmentsecurity.org/articles/crack-unix-linux-passwords.html

	== Protection against brute-force ==		== Protection against brute-force ==

Rootadminacc: Created page with "== Autokick SSH user after specified time == if [ -n "$SSH_CONNECTION" ]; then export TMOUT=300; fi This will check if a user is logged in using ssh and will log out the use..."

2013-01-15T11:36:45Z

Created page with "== Autokick SSH user after specified time == if [ -n "$SSH_CONNECTION" ]; then export TMOUT=300; fi This will check if a user is logged in using ssh and will log out the use..."

New page

== Autokick SSH user after specified time ==

if [ -n "$SSH_CONNECTION" ]; then export TMOUT=300; fi

This will check if a user is logged in using ssh and will log out the user automatically after the specified time in seconds without data retrieval on the server side. Will work with bash and zsh so put it into your sourced shell file on the server side. Be aware that users can change this themselves as it's just a environment variable.

== Clear bash history ==

export HISTSIZE=0

== Create secure password in SSH ==

genpassdeep() { cat /dev/urandom | tr -dc [:alnum:] | head -c64 | whirlpooldeep; echo; }

== Disabling the root user ==

Enter this file:
<pre>vim /etc/ssh/sshd_config</pre>
Set this value:
<pre>PermitRootLogin no</pre>
Exit the file and type:
<pre>visudo</pre>
Under User privilege specification (on Ubuntu) or Allow root to run any commands anywhere (on CentOS)
<pre>root ALL=(ALL) ALL
username ALL=(ALL) ALL</pre>
Restart SSH and now the root user cannot log in unless done via the new user with root privileges:
<pre>/etc/init.d/ssh restart</pre>
Do not close your current connection and open a new connection:
<pre>ssh -pX username@IPaddress (where X = your SSH port number)
sudo su -</pre>

== [http://www.md5hashgenerator.com MD5 Hash Generator] ==

== [http://serverkb.co.uk/wiki/General_Linux#File_Permissions Permissions] ==

== John the Ripper ==

http://www.osix.net/modules/article/?id=455 
http://www.openwall.com/john/doc/EXAMPLES.shtml ([http://www.openwall.com/john/doc/CONFIG.shtml Config]) 
http://pka.engr.ccny.cuny.edu/~jmao/node/26 
http://pentestsh.webs.com/apps/blog/show/20717358-netbios-nbns-spoofing#.UL-DZMmkqso.twitter



== Password Safety ==

http://www.google.co.uk/goodtoknow/online-safety/passwords

== Protection against brute-force ==

Some methods that may help to increase OS security against external attacks including brute-force are:

* Use key-based authentication only
* [[Security#Disabling_the_root_user | Close SSH access for the root user]]
* Configuring of sshd daemon listening to using of exclusive IPs only
* Change sshd daemon port from 22 to another in /etc/ssh/sshd_config , more information at the [[SSH | SSH]] page.

There is a lot of third-party solutions for the same purpose:

* [http://denyhosts.sourceforge.net DenyHosts] - scans log files and configures tcp wrapper rules
* [http://cryptknock.sourceforge.net Cryptknock] - opens the ssh port if required
* [http://blocksshd.sourceforge.net BlockSSHd] - analyzes logs and configures firewall rules
* [http://www.sshguard.net SSHGuard] - monitors logs and configures firewalls

== Tools ==

[http://freecode.com/projects/rkhunter rkhunter (Rootkit Hunter)] 
[http://sourceforge.net/projects/sentrytools/ Sentry Tools]

To check the rkhunter log for problems on Linux do:

cat /file/path/rkhunter.log | grep found | grep -v None | grep -v Not 
cat /file/path/rkhunter.log | grep "Warning: Found"

Security - Revision history

Rootadminacc: /* Disabling the root user */

Rootadminacc: /* Password Safety */

Rootadminacc: Created page with "== Autokick SSH user after specified time == if [ -n "$SSH_CONNECTION" ]; then export TMOUT=300; fi This will check if a user is logged in using ssh and will log out the use..."