I'm currently building a network monitoring system that will notify me if any interface errors or network issues. after building it we would like to be able to test if it works before implementing it to our network, so need a way of simulating network interface errors on a switch or networking device?
I was thinking about cutting ethernet cables or terminating them wrong, but ideally I need soemthing that can create loads of different types of interface errors
any help would be much appreciated
Sean
You could download Nagios which is a powerful, enterprise-class host, service, application, and network monitoring program. Designed to be fast, flexible, and rock-solid stable. Nagios runs on *NIX hosts and can monitor Windows, Linux/Unix/BSD, Netware, and network devices.
you can download other network monitoring systems from sourceforge they have many different network tools written in different languages most of them are open source. you can take notes of their
design and maybe add to the application you building.
if you want to test your application the best thing to do is to tested on real environment, I believe their might be one or two Virtual Lab.
But Ideally I would tested on real interfaces
One of the ways to simulate network failures would be to dynamically change the firewall settings. You can make packets drop, hosts, disappear, etc. This doesn't require any physical damage to anything :)
Related
I've been asked to implement VPN capabilities in an existing software project on an embedded system, in order to make the device available via network to an external server while avoiding trouble with firewalls (no need for encryption, just to make it accessible).
Unfortunately, the embedded system is based on a Cortex-M4 MCU, therefore Linux, which would allow for VPN nearly out of the box, is not an option. All I've got is an RTOS and a working LwIP stack.
I've used VPNs in the past. However, my network knowledge is rather limited concerning implementing VPNs, so I'm rather stumped. As I think, I'd use the current LwIP instance for building up the tunnel connection, and the application would use a second instance for the actual network communication, while the network interface of the second instance is a virtual one (like a tap device on linux), encapsulating its low level data and tranceiving it via the tunnel connection of the first LwIP instance.
Maybe this way I'd be able to create a custom solution for the problem, but the solution should conform to any standards (as the server will be any kind of sophisticated system).
So I wonder if anyone has been confronted with a task like this, and would appreciate any hint what to do, at least a direction where to look at.
Thanks in advance!
Consider the following situation:
You have an application you are tesing, but in order to test the networking functionality of said program, you are required to run multiple instances of it and have them communicate with one another.
Possible solutions are:
- Run software on individual machines connected by WAN or LAN.
- Run the software on virtual machines, all on the same computer.
I do not want to use either of these methods (the reasoning is irrelevant). I want to know if there is a way that I can reroute network transmissions from the test application (ideally in any programmming language) in a way such that I can run multiple instances of the same software on one computer, and have them behave as if they were the only instance running on that computer.
In other words, I want to be able to code the application so that each instance listens on the same "listening" port (since only one instance will be running on each computer when in production). Then, I want to know if I can reroute the network requests at a lower level then the application so that they do not interfere with eachother (clash over the same port number).
Essentially, I want to build a virtual environment which only redirects the network calls (whereas a virtual machine takes far more resources, and has way more involved). Is this possible, and how might I approach this problem?
Thank you!
UPDATE: This is a more accurate idea of what I want to accomplish:
Basically, I want to program another application which TRANSPARENTLY redirects bind requests to available ports, and manages which applications are bound where... So from the applications perspective, all the instances are bound to port 1000, but in reality, this other application is automatically managing which instance is bound where, and avoiding potential conflicts. I feel like this could be accomplished with Windows Hooks, but I'm not sure how you could implement this?
As far as I know, there is no sane way to multiplex the same port on the same network device. At the very minimum, you will need to choose on of the following:
Run each instance of your program on a different port
Create multiple virtual network interfaces
The first choice is easy and may be the one I would choose. The second one is more towards what you are looking for but it would be a true PITA to set up - you can look into VirtualBox and its host-only networks for inspiration. If you are writing things on linux you might look into pipes and chrooting but you'll be spending more time setting up this environment than writing your software.
I am a beginner in User Mode Linux Area, and recently started working on it, by reading material available in Internet e.g; http://user-mode-linux.sourceforge.net/source.html.
My Objective :
Currently I am performing some tests, On which I am using direct hardwares : e.g;
APs[Access Points]- Configured with different types of NAT [ Full Cone, Port Restricted,Symmetric etc] and Desktop's
Rather using such all hardwares Computers ,Desktops etc, I think I may use something like User Mode Linux which all together light-weight Linux's Virtual Instances, On that I can simulate my task e.g; Virtual Switch, Virtual light-weight Instances
I tried a lot by using several Virtual Machines (VMWare) on same machine to Simulate different networks , and networks supposed to be connected Virtual Switch (didn'y find any).
All together -
[1]. Is there any one who has such past experience , Where you have simulated real network with the help of either Virtual Machines(UML or Virtual Box or VMWARE) and Virtual Switch (I don't know any).
[2]. If yes, Is it require too much effort ? means do you feel configurations are not much complex ?
There is such a product.
It is called GNS3 VirtualBox Edition:
http://forum.gns3.net/topic3262.html
I've used vde to simulate a network in the past. It's great and lets you setup things like virtual switches (http://wiki.virtualsquare.org/wiki/index.php/VDE). What I simulated were 5 virtual machines (using qemu) connceted to a virtual switch (using vde).
I'm not sure what the state of affairs is with virtualization products, but somethign like VMWare might also allow you to create a virtual network but I doubt it would be as flexible as VDE.
User Mode Linux is like very old, I would suggest using VDE as suggest by sashang, but simulating networks can he helpful.... However it's purely simulation, real devices in the real world can behave differently and vice verse....
There are a number of open-source network simulators, which help automate the process of creating virtual machines and connecting them together, that you might find useful. I created a list of these tools, along with some tutorials, and posted it at: http://www.brianlinkletter.com/open-source-network-simulators.
Hi Guys I'm debugging some CS program and to view the performance of the application in slow internet I tried many different ways. However the best would be the Server and the client be in the same PC ---- my debugging environments for both the server side and the client is setup in one PC.
So I'm wondering is there anyway to limit the speed? I'm using TCP but I don't know too much in-depth knowledge of it.
Thank you
There are two important factors regarding a "slow" internet connection that you need to test out since they have different implications for your application: bandwidth and latency.
If you provide some more details about what os you are running your tests on, it would be easier to recommend a way to limit the network performance.
On a related side note, it's generally a bad idea to performance test any kind of networking using the loopback device on your machine, since many aspects of this will perform very different than the regular network device on your machine.
You mention in the comments this needs to be done on windows, while the Network Emulators I know of (e.g. netem, TCN, other variants) all require Linux. So one thing you could do is create a virtual machine (VirtualBox is fine, I did similar things with it), install linux on it, configure 2 network interfaces, emulate the slow/long/lossy/jittery network between them, and route the test traffic through it from windows.
Finally I found this does what I need.
http://www.nirsoft.net/utils/socket_sniffer.html
Captures Windows Socket traffic, no matter it's local or not.
I have an old school foxpro web app that I am trying to help limp along while I rewrite the system. Every day, multiple times, I get this following error message: The specified network name is no longer available.
Does anyone have any suggestions how to troubleshoot this? Perhaps, prove to my IT guys that there really is a network issue. I have theories, but I have no idea how to prove anything, it always comes back to foxpro sucks rewrite it now.
I'll take any help, tools, and will answer any questions that may clarify this for you.
thanks
We have a very large multi-user VFP application on hundreds of sites. Occasionally you get this sort of problem. It is almost always down to environmental issues.
Had one just recently where a client had two machines continually crashing out of the VFP application. Network IT guys swearing up and down that it's not their problem. But what's this in the System Log of both machines? Why, it's the Broadcom NIC reporting a network link loss detected at the same times the application crashed.
Check if the client and server NICs in your situation can report this.
You could consider writing a small program that pings the network resource periodically. You might just look for a file and if the network is failing and the program cannot find the file email the folks in charge of the network and yourself. This would be an independent app, and best if not written in FoxPro so you can independently prove it is not the application or the language/tool it was written in.
I have seen this when networks have bad wiring, a bad port on the switch/hub, a failing NIC in the mix, and sometimes when the network is just flooded with requests from workstations.
You also did not mention if this was a wireless connection. I am hoping not, but I have seen wireless (especially slower wireless) hubs fail with respect to the network overload and slow and unreliable performance. Especially compared to a wired network.
Rick Schummer
In addition to the comments about IP address, is the setting on the network controller to be energy efficient? and thus turn itself off when not actively in use.