Basic RouterOS under VirtualBox

Following my post on Installing Mikrotik RouterOS in VirtualBox, here is some basic configuration setup if you want to play around with RouterOS.
For real hand-on experience better to buy small a Mikrotik (e.g RB750, RB951G-2HnD) , they are very cheap. Check here for the products and prices.

Add more Ethernet Interfaces

One simple way to add more interface is to use USB-to-Ethernet adapters. Once installed check that they appear correctly under host OS Linux.

Installing GNS3 v0.8.6 on Linux

Below are the basic steps for installing GNS3 v0.8.6 on Linux Mint 15 ( should also work for other similar flavors) using the excellent work by  claydon_dan as posted in GNS3 Forum.

This version makes things much easier in installing GNS3 and Dynamips using PPA (Personal Package Archive). Reposting the steps below.

Step 1: Add PPA to your system

sudo add-apt-repository ppa:gns3/ppa

How to find motherboard model in Linux

There are many ways, using command line in LINUX, to see the motherboard model of the computer. 
You can use lshw or dmidecode. Read more on cli syntax from man commands.

Installing TFTP server in Linux

I recently needed a file server to keep boot images and configuration files to be transferred on switches and routers.

I decided to use TFTP because of its simplicity and low memory requirements
Below the installation steps  used on a  computer loaded with Linux Mint 14.

Installing Mikrotik RouterOS under VirtualBox

MikroTik RouterOS is a Linux based operating system that runs on proprietary hardware (RouterBOARD), or on standard x86-based computers. Some training videos here.

You can install it in VirtualBox and play around with this virtual device.
For real hands on experience with Mikrotiks , better buy the actual equipment since they are cheap.

Go to their website and download the latest Router OS for PC/86

At this time v5.18 is latest stable available version. Also available in torrent.

Create a new Virtual Machine in VirtualBox as per example below.

xDSL- Loop qualification

Below some material found on the web ( webinars, application notes, white papers, articles etc.) on DSL troubleshooting , mostly from companies that manufacture xDSL Testing equipment.

SSH Tunneling

You can create SSH Tunnels using different kinds of forwarding like
a) Local Port Forwarding, 
b) Remote Port Forwarding,
c) Dynamic Port Forwarding
c) X Forwarding

For a full command syntax check the online man pages for ssh  here  

Rate Limit on Cisco 3550

I have a Cisco 3550 and  want to apply rate limit on the interfaces for both ingress and egress. 
As per Cisco documentation in
Understanding QoS Policing and Marking on the Catalyst 3550
"Policing is not to be confused with traffic shaping, although both make sure the traffic stays within the profile or contract.
Policing does not buffer the traffic, so policing does not affect the transmission delay. Instead of buffering out-of-profile packets, policing drops them or marks them with different QoS levels (DSCP markdown).

Traffic shaping buffers out-of-profile traffic and smoothes the traffic bursts, but affects the delay and delay variation. Shaping can only be applied on the outgoing interface, while policing can be applied on both the incoming and outgoing interface.

The Catalyst 3550 supports policing for both incoming and outgoing directions. Traffic shaping is not supported."

Calculations on Linux

Command Line calculator

how to perform standard calculations on the command line including addition, subtraction, multiplication, division, powers, square root, conversion.


From man pages

bc - An arbitrary precision calculator language

How to add source code in Blogspot

I was googling around to find a way to post source code in the blog pages that look better compare to the default.

I run into these :

1. google-code-prettify
2. syntaxhighlighter
3. Format source code for blogspot

For now I'm using the last one.

Basic DHCP on Cisco Router

Configuring DHCP IOS DHCP server

Sequence of DHCP messages :

1. Client sends a broadcast DHCPDISCOVER message to the server
2. The DHCP server replies with a DHCPOFFER message containing the IP address, subnet mask , gateway and other parameters.
3. The client sends a broadcast DHCPREQUEST message to the server, requesting the offered address.
4. The DHCP server replies with a broadcast DHCPACK packet to the client.

DHCP server was designed to work within the same broadcast domain as the clients.
If DHCP server is behind another router , that router must become a DHCP Relay Agent. The DHCP relay will intercept the broadcast DHCP messages from the client and will forward them to the server as unicast messages. See at the end of this post a setup based on this scenario.

My network setup in GNS3 shown below 

SSH useful commands

I post below some useful SSH commands


Secure Copy File Transfer

SCP copies files between hosts on a network. It uses ssh for data transfer, and uses the same authentication and provides the same security as ssh. Some examples here

From a remote host to  local host

scp -P10022 192.168.2.10:/home/stelios/Desktop/Etherchannel.zip /home/stelios/Desktop/  
 Etherchannel.zip                                            100% 137KB 136.6KB/s  00:00   

More that one file from localhost to remote host

scp -P10022 test01.txt test02.txt 192.168.2.10:/home/stelios/Desktop/  
 test01.txt                                                 100%  0   0.0KB/s  00:00    
 test02.txt                                                 100%  0   0.0KB/s  00:00    

From the local host to a remote host

scp -P10022 /home/stelios/Desktop/Multicast.zip 192.168.2.10:/home/stelios/Desktop/  
 Multicast.zip                                               100%  75MB  1.5MB/s  00:49    

Secure Copy  directory from local to remote host

scp -P10022 -r /home/stelios/Desktop/scp_test 192.168.2.10:/home/stelios/Desktop/  
 WHowe_gns3_vbox.pdf                                       100% 1902KB  1.9MB/s  00:00