Brain's Workbench
Assumptions:
NFS Server IP: 172.16.5.100
NFS Client Node1: 172.16.5.101
NFS Client Node2: 172.16.5.102
NFS Client Node3: 172.16.5.103
NFS Client Node4: 172.16.5.104
On the NFS Server & All Client machine as well:
yum install nfs-utils nfs-utils-lib
Edit the exports file that shows what to share and with whom. So run:
To enable and load mod_rewrite, do the following.
$ sudo a2enmod rewrite
Then open up the following file, and replace every occurrence of “AllowOverride None” with “AllowOverride all”.
$ sudo vi /etc/apache2/sites-available/default
or
$ sudo vi /etc/apache2/sites-available/000-default
Finally, restart Apache2.
$ sudo service apache2 restart
First of all, you should get the “nmap” package installed in your system.
On CentOS
yum install nmap
On Debian
apt-get install nmap
On Ubuntu
sudo apt-get install nmap
NMAP Commands:
sudo nmap -sS [IP address] or [website address]
sudo nmap -O --osscan-guess [IP address] or [website address]
sudo nmap -vv [IP address] or [website address]
sudo nmap -sV [IP address] or [website address]
nmap -sn 192.168.1.0/24 or nmap -sP 192.168.1.0/24
This is performed on a CentOS 6.x 64 bit machine
Install pen which is lightweight simple Load Balancing software.
It is TCP protocol based, so it’s possible to balance not only HTTP but SMTP, FTP, LDAP and so on. This example is based on the environment like follows.
Configure Pen to load balance to Backend#1, Backend#2, Backend#3 web servers.
So the Webmin on Redhat/CentOS is now requiring this particular perl module to be pre-installed before the RPM installer begins.
A very short cut to install this module by using yum-
yum install -y perl-Net-SSLeay
Voila! your done.
In order to create a multi tenancy in zimbra OSA, can be acheived through a bash script below. Thanks to Ahmad Imanuddin (http://www.imanudin.com) for sharing this very useful script.
cd /srv/ vi admin-delegate.sh
Fill with the following line :
Through zimbraGUI didn’t find it how to do it, but through console it appeared to be working with the following set of commands to modify postfix actually-
su zimbra zmprov mcf zimbraMtaMaxMessageSize 20971520 zmprov mcf zimbraFileUploadMaxSize 20971520 zmprov mcf zimbraMailContentMaxSize 52428800 zmprov modifyConfig zimbraMtaMaxMessageSize 52428800 postfix reload
Once theyre executed, restart the server (restarting zimbra won’t reflect the changes made, so need a fresh reboot of OS)
Problem Description
You have built two or more network cards into one Linux system and each of these cards has its own default gateway. By default, you can only have one default gateway on a system. The case described would lead to asynchronous routing, whereby the router would reject the packets as appropriate.
Solution
The iproute2 program, which is included in all current Linux distributions and already installed even, as a rule, can be used for the solution of this problem. Normally, a Linux system only has one routing table, in which only one default gateway can make entries. With iproute2, you have the ability to setup an additional routing table, for one thing, and allow this table to be used by the system based on rules, for another.
Scenerio-
eth0- 172.30.0.100 | Gateway- 172.30.0.97
eth1- 192.168.2.247 | Gateway- 192.168.2.1
Need to connect to SIP BOX destination (fictitious)- 202.140.1.1
eth0 has not internet access but it uses the mentioned (172.30.0.97) as gateway to reach 202.140.1.1 server
eth0 has internet access by using 192.168.2.1 gateway.
Here goes the configuration on /etc/sysconfig/network-scripts/ifcfg-eth0
Downloading Cacti
You can download the newest version of Cacti from its website.
wget http://www.cacti.net/downloads/cacti-0.8.7b.tar.gz
Installing Cacti
Install apache webserver with php support, mysql database server, snmp, some php modules and rrdtool.
apt-get install apache2 libapache2-mod-php5 php5 php5-cli php5-mysql php5-gd php5-snmp mysql-client mysql-server libmysqlclient15-dev snmp snmpd rrdtool
Add a user account for cacti.