Change hostname on Linux Mint

Change hostname on Linux 

To see current hostname settings, type 
hostnamectl

Change hostname using hostnamectl command 
hostnamectl set-hostname <newhostname>

hostnamectl set-hostname homelab1

Another method is to replace old hostname with new hostname in files /etc/hostname and /etc/hosts then reboot the machine.
sudo nano /etc/hostname

sudo nano /etc/hosts

sudo reboot

Reference:

Manpage hostnamectl

Installing FTP server on Linux

I need an FTP server running on my computer for configuration file backup.
Below the instructions how to setup vsFTPd server on Linux Mint , in stand alone mode.


Install the vsftp deamon

sudo apt-get install vsftpd

Make a backup of the default configuration file

sudo cp /etc/vsftpd.conf /etc/vsftpd.conf.backup 

Installing JunOS Olive12.1 in VirtualBox on Linux

If you don't have a real Juniper equipment, there is way to practice with  JUNOS. Of course best way is to have the actual Juniper router since many functions cannot be simulated/emulated. Googling around you will find different methods either using VirtualBox, VMware or Qemu. Methods vary from extremely easy to difficult ( if you want to do it from scratch using FreeBSD - JUNOS is based on FreeBSD kernel.)
Below you can find instructions in 5 steps on how to install JUNOS Olive 12.1 in VirtualBox on Linux. For more details and capabilities of JUNOS Olive check this excellent website.

For this Lab setup I want to uses three Juniper routers in the topology they appear below.

Lab topology for testing three juniper routers

Copper Loop Qualifications and Troubleshooting Line Impairments

The following factors are affecting the performance of a copper pair and problems are increasing with the higher frequencies involved in ADSL/VDSL. The below conditions, should be tested when delivering  a new service or during fault diagnosis.

• Return Loss
• Insertion Loss
• Longitudinal Balance
• Crosstalk
• Noise
• Interruptions
• Split Pairs
• Gauge Changes
• Bridge Taps
• Bad Cable Twisting

Installing TFTP server atftpd in Linux

I need a TFTP server to keep configurations files. I need the server to be simple to setup and be able to send or receive any file without any restrictions. It would be for a lab environment so a strict security is not necessary. I'm using Linux Mint.
In Linux I could find three different TFTP servers: 

• tftpd
• atftpd
• tftpd-hpa

Already tried tftpd see my other post Installing TFTP server in Linux. A minor problem is that you cannot transfer a file to the TFTP server.

Installing atftpd

sudo apt-get install atftpd

Remote console with a Mikrotik

I was testing the remote console feature on my Mikrotik (RB951G-2HnD). Detailed information posted on Mikrotik wiki on Manual:Port.

If you want to access serial device that can only talk to COM ports and is located somewhere else behind router, then you can use remote-access.

As defined in RFC 2217 RouterOS can transfer data from/to a serial device over TCP connection.

Enabling remote access on Mikrotik is  easy , see the steps below.

PLUG IN THE USB-TO-SERIAL ADAPTER

As soon as you plug in the USB-to-Serial Adapter you will see all available port and how they are used.  

3G Backup on Mikrotik

I was playing with my Mikrotik at home (RB951G-2HnD) trying to learn more stuff and though I should put of some use to my 3G USB dongle (HUAWEI E220). This came in handy as next day my main connection had problems and needed a backup connection to the Internet.

PLUG IN THE MODEM

Plug the 3G USB dongle and check on Mikrotik using the CLI commands "system resource usb print". If it can recognize the 3G modem then you are ok .See the command output below :

QinQ with Cisco Catalyst switches

Below a simple topology using QinQ tagging (officially known as IEEE 802.1ad or unofficially IEEE 802.1 QinQ ) on Cisco Catalyst C3550 switches.

C-VLANS 10 and 20 come from customer side and are encapsulated in the S-VLAN 1800.

This feature is also called VLAN double tagging or Vlan stacking, or Nested VLANs (Allied Telesis) or vMAN technology ( Extreme Networks).

VirtualBox in GNS3 under Linux part2

Continuing the previous post  VirtualBox in GNS3 under Linux part1, I will show below the steps on how to make GNS3 work with Virtualbox using emulated VirtualBox host-only adapters. 

STEP 1 : Install VirtualBox and VMs
Install VirtualBox (current version is 4.3.6) and your favorite Virtual Machines.

VirtualBox in GNS3 under Linux part1

Following my previous post on Installing GNS3 v0.8.6 on Linux , now will make GNS3 work together with VirtualBox.

By the time GNS3 started supporting VirtualBox virtualization ( v0.8.1 ), things were made easier in using VMs in GNS3. You just tell to GNS3 which VMs to load. see below the steps in detail. For more info see GNS3 website.

Later ( easy installation ) it became even simpler and no need any more to start GNS3/VirtualBox in root access mode.

STEP 1 : Install VirtualBox and VMs
Install VirtualBox (current version is 4.3.6) and your favorite Virtual Machines.

802.1Q VLAN trunk in Linux

I need to configure an Ethernet interface as an IEEE 802.1q VLAN trunk on Linux Mint for Lab purposes so I can connect GNS3 with a physical Cisco Switch. So I will create 6 vlan interface using VLAN ID 101-106 on eth0 interface.

Install VLAN package

 sudo apt-get install vlan 

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