[GRE] How to create gre environment - method 1

===== VM1 settings =====

gedit /etc/network/interfaces

modprobe ip_gre

auto tun0

iface tun0 inet static

       address 10.0.201.2

       netmask 255.255.255.0

       broadcast 10.0.201.255

       up ifconfig tun0 multicast

       pre-up iptunnel add tun0 mode gre local 111.2.1.130 remote 111.2.1.97 ttl 255

       pointopoint 10.0.201.1

       post-down iptunnel del tun0





Create a interface was called eth3

Assign a IP address is 192.168.111.1

Reboot.



===== VM2 settings =====

gedit /etc/network/interfaces



modprobe ip_gre

auto tun0

iface tun0 inet static

       address 10.0.201.1

       netmask 255.255.255.0

       broadcast 10.0.201.255

       up ifconfig tun0 multicast

       pre-up iptunnel add tun0 mode gre local 111.2.1.97 remote 111.2.1.130 ttl 255

       pointopoint 10.0.201.2

       post-down iptunnel del tun0



Create a interface was called eth2

Assign a IP address is 192.168.222.1

Reboot



===== Experiment =====



==== Test 1 ====

ping from "VM1 of tun0(10.0.201.2)" to "VM2 of tun0(10.0.201.1)" (OK).



==== Test 1 ====

If eth3 want ping to eth2 must add route rule to routing table.

sudo route add 192.168.222.0 netmask 255.255.255.0 gw 10.0.201.2 dev tun0

After this script, then ping successfully.



Reference :

• Creating an IP Tunnel using GRE on Linux  (Very Important)
• Ubuntu 12.04 Server: GRE Tunneling
• 深入理解 GRE tunnel
• GRE Tunneling How to
• Bridging across GRE tunnels (experimental)
• Tunneling - GRE/L2TP
• Understanding and Configuring VLAN Routing and Bridging on a Router Using the IRB Feature
• /etc/network/interfaces
• networking - How can I add encryption to a GRE tunnel?

Other :

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iface zeus inet static

address 192.168.0.2

netmask 255.255.255.0

network 10.0.0.0

pre-up ip tunnel add zeus mode gre remote 212.120.124.15 local 130.89.193.99 ttl 255

up ip link set mtu 1500 dev zeus

up ip ro add 10.0.0.0/24 dev zeus

up ip ro del 192.168.0.0/24 dev zeus

post-down ip tunnel del zeus

##############################

iface zeus inet static

pre-up ip tunnel add zeus mode gre remote 111.5.3.143 local 111.2.1.130 ttl 255

up ip link set mtu 1500 dev zeus

up ip ro add 10.0.0.0/24 dev zeus

up ip ro del 192.168.0.0/24 dev zeus

post-down ip tunnel del zeus

##############################

iface zeus inet static

pre-up ip tunnel add zeus mode gre remote 111.2.1.130 local 111.2.1.97 ttl 255

up ip link set mtu 1500 dev zeus

up ip ro add 10.0.0.0/24 dev zeus

up ip ro del 192.168.0.0/24 dev zeus

post-down ip tunnel del zeus

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