Monthly Archives: January 2013

How to extend the root partition in LVM

In this tutorial, I am using the CentOS6(but also applicable on other Linux distro) that has ext4 partition lv_root mounted as / and lv_swap as swap from the volume group vg_centos6 (which is default), we pretend that we are running out of space in lv_root(/) and volume group (vg_centos6) doesn’t have any free space. We added a brand new drive with 20 GB space. Now, we need to assign this 20 GB space to volume group and then extend lv_root(/).

WARNING: Backup your data before attempting this.

First, we’ll check the file system disk space usage and logical volume information:

sudo df -h
sudo lvs

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Authenticate the Cisco Devices using FreeRADIUS on Ubuntu

secnario

We want to authenticate and authorize the user on Cisco devices using the Free Radius on Ubuntu Server. In this tutorial, we want to create two users, Arbab and Ali. Arbab have full access to Cisco devices (privilege level 15) while Ali has custom access (like show commands including show running and interface configurations) only.

FreeRADIUS configuration on Ubuntu:

Install FreeRADIUS by using the following command:

sudo apt-get install freeradius

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OpenVPN Client Configuration on Ubuntu 12.04

To use the Ubuntu as OpenVPN client, install these packages:

sudo apt-get install network-manager-openvpn

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Authenticate the Cisco Devices using Active Directory

Router and AD copy

We want to authenticate and authorize the user on Cisco devices using the Microsoft Active Directory. In this tutorial, we want to create two Active Directory groups, Network Admin and Network Tech. Network Admin have full access to Cisco devices (privilege level 15) while Network Tech have custom access (like show commands including show running and interface configurations) only.

arbab belong to the Network Admin group

ali  belong to the Network Tech group

Network Policy and Access Services:

Before starting this tutorial, I assume that you have installed the Active Directory and it is up and running. Let’s start the tutorial by adding the NPS Role:

Start -> Administrative Tools -> Server Manager

1 copy

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How to Change the Network Cards Priority in Windows 7

wire-wireless

Scenario:

We are connecting with the two different networks using the wired and wireless cards simultaneously . We want to access the local resources (e.g: file server, print server, application server etc) using the wired connection while  want to browse the Internet using the wireless connection.

To check the default Network Cards Priority, open up a command prompt and issue this command:

netstat -r

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How to Fix Postfix File too large error

Today, I was getting an error from my Postfix mail server, when trying to send mysqldump file which is about 8 MB attachment. I checked the /var/log/maillog and found this:

sudo tail -f  /var/log/maillog

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To view the default settings for all the parameters of Postfix:

postconf -d | grep size

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Multiple DHCP Servers on single Mikrotik

mikrotikScenario:

Mikrotik dhcp server with 3 network cards (LAN,Wireless,WAN), WAN is connected to Internet, Wireless is connected to the 10.10.10.0/24 subnet and serve as dhcp server  while LAN interface serve for 172.16.10.0/24 subnet.

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Configure Mikrotik DHCP to assign ip address to only authorized client(s) {2nd Method}

To achieve the same goal, you can also consult this post and decide yourself that which method suit you better!

mikrotik

Scenario:

Mikrotik is working as dhcp, dns, and default gateway for local network.

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