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Showing posts with label network. Show all posts
Showing posts with label network. Show all posts

Sunday, January 18, 2026

My Meshstastic


I'm always curious and so time ago I found out about Meshstastic browsing around.
For a while I said "meh, OK, cool, no time, no resources, no ...." yeah.

Then I did try for a while a kind of equivalent service based only on smartphone : Bitchat 

I like the idea of both, but of course finding somebody on Bitchat is like to win a lottery ticket .. so everything went back on the back back back burner.

Then one day I decided to try to do something with Meshstastic and here we are 

Thursday, September 16, 2021

Internet Speed Monitor - part 2 - basic SW

 Let see in more details how to put together the basic  internet speed monitor contraption.
This article discuss setting up the Raspberry Pi.

Sunday, September 12, 2021

Internet Speed Monitor - part 1 - specifications

Recently my connection with the provider for internet, has some problems.
Running some speed tests from different computers shows really erratic results.

I should have something about 12 Mbit/s downstream and 2 Mbit/s upstream, some tests shows up to 15 Mbit/s-1.5 Mbit/s, others down to 1 Mbit/s-0.25Mbit/s

Not easy to pin point the nature of the problem.

Wednesday, August 17, 2011

Use Wireshark to monitor a VoIP phone


In a typical LAN environment, today are in use routers and switches.
This improves a lot the performances of a network but make more complicate to monitor a specific appliance, like a VoIP phone. 
In order to capture the traffic on a specific node, assuming is not possible to run a monitor tool on the node itself, it is necessary to use a tool capable to be put between the nodes, or use a switch/router with monitor capabilities.
The main monitor tool in this discussion is the program Wireshark.
There is an article about this issue  on the Wiki for Wireshark .
Since I don't have a switch with monitor capabilities,  the fastest way to set up a generic monitor machine is to use a laptop, with two NIC cards, acting as bridge and running Wireshark on one of the two NIC or on the bridge itself.


Shopping list
It is needed :

  • 1 laptop with Linux installed, with two ethernet ports
  • 1 PCMCA  NIC if the laptop  has already an embedded NIC
  • bridge utilities
  • Wireshark

The environment

The machine used to build the monitor is a Gateway Tablet running Ubuntu 11.04, plus a LinkSys PCMCA NIC  card.
The first step, recognizing the extra NIC card, should not pose any problem.
In my case the LinkSys NIC was recognized and configured automatically by the OS as eth1.
The next step is to install  Wireshark from the Ubuntu repository, and enabled it to capture packets from eth0 or eth1.
Here the configuration  adopted for the machine :
  wshark_1.png
Bridge setting
After preparing the hardware and tested both the ethx ports, it is necessary to set up the machine to act as a bridge, in order to have packets received from the eth0 port sent to the eth1 port, and viceversa.
Without such functionality, the two networks are isolated, i.e. the phone can not receive anything from the network.
In order to simplify the configuration, I forced on both the NIC a manual address.

  • 192.168.2.70
    for the eth0
  • 192.168.2.71
    for the eth1.

After opening a terminal,  install the  brctl  program (sudo apt-get install bridge-utils).
The bridge-utils are not installed by default in the Ubuntu 11.04 but are available in the repository.
At this point I created, configured and activated  a bridge between the two NICs.
  • sudo brctl addbr wshark
    Create a new bridge called wshark
  • sudo brctl addif wshark eth0 Add the eth0 to the wshark bridge
  • sudo brctl addif wshark eth1
    Add the eth1 to the wshark bridge
  • sudo brctl stp wshark on Enable the STP
After creating the bridge, it has to be activated.
To do so, simply use the ifconfig command :
sudo ifconfig wshark up
At this point the bridge should be  working. 

Running Wireshark

After the bridge is activated is possible to run Wireshark.
Among  the available interfaces to use to capture traffic, it will be present a wshark interface that is the bridge.
To capture data is possible to use it.
That's it.