Comments on: Cisco – Dynamips with Linux loopback (tap) interface

By: Lucein

Lucein — Mon, 19 Jul 2010 17:57:57 +0000

Just a quick heads up.

First excellent post and video.

I’m new to Linux, but I found an easier way to make the tap0 int permanent.

After following the instructions above, go to the interfaces file, located at /etc/network/interfaces.

Get permission and add the following information to that file:

auto tap0
iface tap0 inet static
address 169.254.0.1
netmask 255.255.0.0
gateway 169.254.0.2
pre-up /usr/sbin/tunctl -t tap0

I think this goes without saying, but make sure to change the address to your appropriate address.

I think the last line in that config is the key to keeping the int up even after restart..

Ubuntu 10.04 LTS

By: ihulk

ihulk — Fri, 15 Jan 2010 13:30:43 +0000

Jee, I finally solved problem, I can access my router also from outside systems (ping, snmp..) but I have a strange problem with telnet. I can telnet from router to outside system, but I can telnet on router (except from system where is running dynamips)

By: ihulk

ihulk — Wed, 13 Jan 2010 12:33:49 +0000

I use dynamips running on ubuntu, bridged vmware instance with IP 10.17.8.70. I configured tap1 and added route:

ifconfig tap1 10.18.7.6 netmask 255.255.0.0

route add -net 10.17.12.0 netmask 255.255.255.0 dev tap1

I configured routers R1 and R2:

[[ROUTER R1]]
model=3745
slot 1 = NM-1FE-TX
#slot 4 = NM-16ESW
F1/0 = NIO_tap:tap1
F3/0 = R2 F1/0

[[router R2]]
slot 3 = NM-1FE-TX
slot 4 = NM-1FE-TX
F4/0 = R5 F4/0
F1/0 = R1 F3/0
F3/0 = R3 F1/0
model=3745
R1 F3/0 has IP 10.17.12.101
R1 F1/0 has IP 10.18.7.7 (connected to tap1)

R2 F1/0 has IP 10.17.12.102

from that ubuntu system I can ping, reach all of those interfaces (10.18.7.7, 10.17.12.101, 10.17.12.102)
# ip r
10.17.12.0/24 dev tap1 scope link
10.18.0.0/16 dev tap1 proto kernel scope link src 10.18.7.6
10.17.0.0/16 dev eth1 proto kernel scope link src 10.17.8.70
169.254.0.0/16 dev eth1 scope link metric 1000
default via 10.17.250.250 dev eth1 metric 100

The problem is to reach those interfaces from seem other system, for example from my windows deskop. I added those routes, ubuntu is gw, package forwading on ubuntu is enabled:

Active Routes:
Network Destination Netmask Gateway Interface Metric
0.0.0.0 0.0.0.0 10.17.250.250 10.17.1.153 20
10.17.0.0 255.255.0.0 10.17.1.153 10.17.1.153 20
10.17.1.153 255.255.255.255 127.0.0.1 127.0.0.1 20
10.17.12.0 255.255.255.0 10.17.8.70 10.17.1.153 1
10.18.0.0 255.255.0.0 10.17.8.70 10.17.1.153 1
10.255.255.255 255.255.255.255 10.17.1.153 10.17.1.153 20
127.0.0.0 255.0.0.0 127.0.0.1 127.0.0.1 1
192.168.80.0 255.255.255.0 192.168.80.1 192.168.80.1 20
192.168.80.1 255.255.255.255 127.0.0.1 127.0.0.1 20
192.168.80.255 255.255.255.255 192.168.80.1 192.168.80.1 20
192.168.159.0 255.255.255.0 192.168.159.1 192.168.159.1 20
192.168.159.1 255.255.255.255 127.0.0.1 127.0.0.1 20
192.168.159.255 255.255.255.255 192.168.159.1 192.168.159.1 20
209.85.0.0 255.255.0.0 10.17.8.70 10.17.1.153 1
209.85.135.0 255.255.255.0 10.17.8.70 10.17.1.153 1
224.0.0.0 240.0.0.0 10.17.1.153 10.17.1.153 20
224.0.0.0 240.0.0.0 192.168.80.1 192.168.80.1 20
224.0.0.0 240.0.0.0 192.168.159.1 192.168.159.1 20
255.255.255.255 255.255.255.255 10.17.1.153 10.17.1.153 1
255.255.255.255 255.255.255.255 192.168.80.1 192.168.80.1 1
255.255.255.255 255.255.255.255 192.168.159.1 192.168.159.1 1
Default Gateway: 10.17.250.250

I can reach eth1 and tap1 interface from that windows box, but it seems that packages to routers are droped (10.18.7.7, 10.17.12.101, 10.17.12.102). What I have to do ?

By: Josh

Josh — Mon, 20 Jul 2009 19:07:34 +0000

Fenando,

Try this tutorial.

Josh

By: Fenando

Fenando — Mon, 20 Jul 2009 18:35:15 +0000

Great work.

I was wondering if it is possible to ping another interface of router R1 (that is connected to another router R2) from the linux machine. Moreover, is it possible to ping an interface in router R2?

By: Вячеслав

Вячеслав — Fri, 03 Jul 2009 18:05:52 +0000

Respekt from Russia. It’s really work. Thanks

By: Paul

Paul — Fri, 26 Jun 2009 10:25:52 +0000

Does anyone know if this very useful tutorial is available for GNS?
I am still learning more and more about GNS.

Or, would it be better if I only used Dynamips and Dynagen.

Any advise would be nice, even the simplest.

Thanks

Paul

By: Josh

Josh — Wed, 25 Feb 2009 03:39:31 +0000

Jerry,

It looks like you are trying to run a .net config file with dynagen that was created with gns3.

Josh

By: jerrysimila

jerrysimila — Fri, 20 Feb 2009 07:06:01 +0000

Hi am still taking my baby steps in linux, was trying to connect my gns lab to my real pc and the error i get when i start dynagen is :

root@jerry-laptop:/home/jerry/Desktop/taps# dynagen loopback.net

Reading configuration file…

Shutdown in progress…
Shutdown completed.
Warning: ignoring unknown config item: x = -76.0
Warning: ignoring unknown config item: y = -43.0
Warning: ignoring unknown config item: x = -69.0
Warning: ignoring unknown config item: y = -171.0

*** Error: Could not connect to server: GNS3-DATA
Shutdown in progress…
Shutdown completed.
Press ENTER to continue

please somebody help, appreciate what y’all is doing ..

By: Netha

Netha — Thu, 12 Feb 2009 06:22:07 +0000

hi..
im searching if there any way to create several loopbacks and brdige them with the PC’s NIC with multiple ip addresses..and create subinterfaces in one of GNS router with several networks. can anyone help me to do this