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InterVLAN Routing with Internet Access on Ubuntu

topology

Scenario:

  • Router: Ubuntu Server with 1 network card.
  • Clients:  WindowsXP in VLAN10,Windows7 in VLAN20.
  • Internet: Internet Router on VLAN30
  • Switch: Cisco 2960
Cisco 2960 Switch Configuration:
interface FastEthernet0/12
description CONNECTED TO UBUNTU ROUTER
switchport mode trunk
!
!
interface FastEthernet0/1
description WINXP
switchport access vlan 10
switchport mode access
!
!
interface FastEthernet0/2
description Win7
switchport access vlan 20
switchport mode access
!
!
interface FastEthernet0/24
description Internet Router
switchport access vlan 30
switchport mode access

Ubuntu Router Configuration:

To install the vlan support on ubuntu, use this command:

sudo apt-get install vlan

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Now we shall configure the vlans on Ubuntu router by editing the /etc/network/interfaces:

sudo nano /etc/network/interfaces

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To enable ip forwarding, edit /etc/sysctl.conf file:

sudo nano /etc/sysctl.conf

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Change net.ipv4.ip_forward from 0 to 1:

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Load “8021q” kernel module:

sudo modprobe 8021q

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Restart the Networking service:

sudo /etc/init.d/networking restart

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Verify the vlan configuration:

sudo cat /proc/net/vlan/config

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In order to provide internet access to Vlan 10 and 20 client(s), we need to do NAT on Vlan 30 interface, on which we have configured the Gateway:

sudo iptables -t nat -A POSTROUTING -o vlan30 -j MASQUERADE

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Verify the routing information on Ubuntu:

sudo route -n

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Test from WinXP:

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Test from Win7:

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Hope this will help you!

Please Remember me in your prayers

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OSPF routing between Cisco,Ubuntu,CentOS and Mikrotik Router!

Scenario:

  • Routers: 1 Ubuntu Linux with 3 nics, 1 Centos Linux with 3 nics, 1 Cisco 3640 Router with 3 FastEthernet interfaces and 1 Mikrotik Router with 2 interfaces.
  • Clients: 3 Windows Xp with 1 nic.
IP Details

All the Routers in this scenario have a default password of “zebra“.

Cisco Router:

  • fe0/0: 10.10.10.1/24
  • fe1/0:10.10.50.1 /24
  • fe2/0: Getting through DHCP

UbuntuRouter:

  • eth0: 10.10.10.2/24
  • eth1: 172.16.10.1/24
  • eth2: 10.10.100.1/24

CentOSRouter:

  • eth0: 172.16.10.2/24
  • eth1: 192.168.10.1/24
  • eth2: 10.10.150.1/24

Mikrotik Router:

  • ether1: 192.168.10.2/24
  • ether2: 10.10.200.1/24

Clients:

  • Ubuntu-Desktop: 10.10.50.50/24
  • WinXP-1: 10.10.100.50/24
  • WinXP-2: 10.10.150.50/24
  • WinXP-3: 10.10.200.50/24

Cisco Router Configuration:

UbuntuRouter Configuration:

Restart the Router!!!

CentOSRouter Configuration:

Restart the Router!!!

Mikrotik Router Configuration:

Neighbor verification from Routers:

Route verification from Routers:

Test from Clients:

Make a simple test from Ubuntu-Desktop.

Make a simple test from WinXP-1.

Make a simple test from WinXP-2.

Make a simple test from WinXP-3.

Configure NAT on Cisco Router:

This is just a bonus section, in which we will configure the NAT on Cisco router and also propagate the default route in OSPF. I connect my Cisco Router to DSL Modem and configure it so that it will take IP address through DHCP, as well as configure the inside and outside interface for NAT.

Lazy man access -list for NAT (This is not the perfect access list):

NAT Overload:

Originate the default route in OSPF:

Verify the last resort information on Cisco Router:

Check default route information on all routers :-)

Hope this will help you!