List of Frequently Asked Questions

Can I use a virtual machine setup (e.g. Zen or VMware)?
Using a virtual machine to perform the simulation will work in most cases. However the scheduling of your virtual machine setup may result in an inaccurate timing. Functions like delay or traffic shaping which depend on timing may not work correct. Its strongly recommended to test your setup (e.g. with netperf and ping) for verification. For a tutorial how to setup a virtual machine please have a look here: Howto: setup VMware for Wanulator

How can I simulate a modem/DSL/etc. connection?
As you may have noticed at the moment shaping of traffic is only possible on the outgoing data stream (up-stream) of an interface. To shape in both directions you need to have 2 Interface cards available (using either routed or switched mode) and apply a traffic shaping function on both interfaces up-stream.

How is the traffic shaping working?
The shaping is done by a standard token bucket shaper.

I found a bug – what shall I do?
Please report to us using the Contact page.

If I assign a function to an interface which packets will be affected?
Every function is applied to the packets of the outgoing data stream on the interface it is assigned to.

The Hardware I have seems to be not not supported (e.g. boot problems) – what now?
This may happen as its hard to keep up with the pace of new HW and new drivers being released. There are 2 possible ways to handle this: You can try to tweak the boot params (e.g. to disable hotplugging) – please have a look into the appropriate documentation for a comprehensive list of possibilities. If this doesn’t help you can run the Wanulator within a Virtual machine which should allways run fine even on the latest HW. In any case I would highly appreciate if you could send me a short notice which HW you found problematic.

Why is Wanulator only available as a live CD?
One important criteria for the Wanulator was to generate an easy to use, “out of the box experience”. A live CD solves problems like Linux kernel dependencies or environment dependencies effectively. Furthermore test software like Wanulator is expected not to be used on a day per day basis. A live CD can easily turn any available PC into a temporary test-station within seconds.

26 Comments » for FAQ
  1. Is there a possibillity to make a image for a arm device (low power and space requirement is very helpfull on my labor desktop 😉 ) like PI2 under debian wheezy for instance. We will use a external usb to ethernet adapter as the second port. I can also do port and give you the SD image for free.

  2. bob says:

    Is it possible to throttle more than one port at the same time? Thanks

    • admin says:

      Not sure if I get the question right but if you mean port as in physical interface (in contrary to UDP/TCP port) that is possible. Please note that the throtteling is only applied to the outgoing traffic…

      • bob says:

        Thanks for the reply, So if I have three physical interfaces (one connected to the internet, the other two connected to computers) can I use WANulator to throttle both computers? or is it limited to one computer?

  3. Jeff says:

    I configured Wanulator in bridged mode with a bandwidth limit of 768 kbps.

    I tested the throughput with JPERF and witnessed drops to zero and spikes to higher than 768 kbps.

    I tested the same settings using WANBridge and JPERF shows a more consistent throughput of around 768 kbps with no drops to 0.

    Am I doing something wrong?

    • Jeff says:

      Any thoughts on this? Is this a bug?

      • admin says:

        Hi Jeff,
        sorry for the late reply – I am quite busy at the moment. Usually I use netperf to check the shaping. It is quite possible that this is a bug or at least some incompatibility of the shapeing algorithms parameter with the pattern jperf uses for the testing. I will check at home a setup with jperf as soon as possible. If possible I would be interessted to hear from you if you get similar results with netperf.

        Kind regards, Michael

        • Jeff says:


          No worries on the late reply. I was very hopeful to use your software for my Master’s paper, but had to use a different emulator because of the JPERF results.

          I didn’t know if your shapeing could work correctly with an application and incorrectly with JPERF.

          Let me know if you have time to check it out. I really like your version.

          I will look into using netperf to test and report back.

  4. Patrick says:

    Is there a way to automate changing the interface attributes? I would like to run a script on a machine, connected either via a network connection or by serial, that would for example change the loss percentage from 0% to 5%.

  5. Annie says:

    Hi there, I wanted to let you know that I was recently setting up a new PC to run Wanulator on it on permanent basis but for some reason, the CD never boots up. After the initial boot up, I get black screen with cursor only. I have had problem with another linux distro on this PC and it was concluded at the time that this PC has SiS Mirage graphic processor which could be the cause. I was hoping that Wanulator will work on it :)

    Anyhow I just wanted to let you know that this CD wont boot on anything that has SIS MIRAGE graphics chip.

  6. Markus says:


    is it possible, to install WANulator on hdd? i don’t use updates. i want use the iso and install this on hdd.

    kind regards

    • admin says:

      I fear there is no easy way to do so – as there is no installer software on the live cd. I will put in on the list for the next update as this request is quite frequent.
      If you want to go experimental you could try to boot the iso, connect the pc to the internet, install Ubiquity (https://wiki.ubuntu.com/Ubiquity) or similar and go for it.
      I have no clue if this is going to work – I never tried this myself – however I would be interessted to hear from you if it worked.

      Kind regards,

      • Jeremy Poulter says:


        For what it is worth we have had some success installing Wanulator on these devices; http://www.mini-itx.com/store/?c=27. They are perfect for a dedicated Wanulator device as they come with flash memory, two network ports and are a reasonable price. We now have 6 of these in regular use.

        Here is how (and I know it is a bit of a hack, well quite a large hack 😉

        – Create Bootable USB drive
        – Download the Universal USB Installer: http://www.pendrivelinux.com/universal-usb-installer-easy-as-1-2-3/
        – Rename WANulator 2.0 ISO ubuntu-11.04- – wanulator_2_0.iso
        – Run Universal-USB-Installer-x.x.x.x.exe
        – Click ‘I Agree’
        – Select ‘Ubuntu 11.04′ in step 1
        – Select ubuntu-11.04-wanulator_2_0.iso in step 2
        – Select USB pen drive in step 3
        – Optionally add some persistent storage
        – Click ‘Create’
        – Install on internal storage
        – Insert USB device into PC and boot from it
        – Once booted close WANulator
        – open an xterm (right click -> xterm)
        – enter command;
        dd if=/dev/sdb of=/dev/sda bs=8M
        – Once complete reboot and remove USB stick

  7. Annie says:

    Hi, First I would like to congratulate you on making this test tool.

    I wanted to know if it is possible to disable / enable DNS and UDP using this tool. I want to see how my client device behaves when i disable DNS. Thanking you in advance.

    Kind Regards

    • admin says:

      Hello Annie,
      you can use a drop function and apply it to every packet. In the filter setting of the function you can limit the drop to UDP or DNS (both exist in the standard filter list).
      I hope that will do the job for you.

      Kind regards,

  8. Fari says:


    what does the Offset Parameter in the w2filterdefs.xml mean? Can i filter ip adresses with another Offset value?
    And somehow the Scramblefunction doesn’t work. I edit, select every packet or something else, click Ok but the its still marked as off and therefore it doesnt scramble!?


    • admin says:

      Hi Fari,
      first of all thanks for reporting the scramble problem there was a bug in the settings dialog. I just uploaded a version which should fix this.
      The offset parameter is the position for comparing the “content” within the received packet. For filtering an IP address this should be 26 for the source and 30 for the destination address – if I am not mistaken. This is assuming a commonly used ethernet2/DIX header with just 2 byte type field behind the addresses (no tagged header with vlan, snap or similar).

      Kind regards, Michael

  9. Vova says:

    >open a xterm and edit the w2filterdefs.xml file you find in the /root directory.

    So can I write filter directly in this file? Any documentation?

    What I need is drop RCT TCP packets (may in with some probability). Is it possible?


    • admin says:

      yes you can edit the file directly (you need to restart WANulator afterwards). Currently I have no documentation – but if you have a look into the file you will find it quite abvious – yust have a closer look to the given examples. I am not sure what you mean by RCT / TCP packets? Could you give a pointer to the protocol or spec?

      Kind regards,

  10. Kev says:

    Is it possible to manipulate only RTP Packets?

    • admin says:

      Hi, unfortunately you cannot filter RTP directly (at least not with a static filter used in WANulator). So you have two options:
      Use the UDP filter (in case you have no other UDP traffic which you want to exclude from manipulation)
      Or you need to know the port number the traffic is destinated to (or sourced from) – which may be a problem if the port is dynamicaly chosen.
      In that case you can add a filter by closing WANulator, open a xterm and edit the w2filterdefs.xml file you find in the /root directory.
      E.g. the offset should be 36 and the content the hex value of your destination port…

      • Kev says:

        UDP isn’t an option, because there is other UDP traffic that I want to exclude from manipulation.
        So i added a filter called RTP with an offset of 36 and a hex port value of 0bb8 (3000).

        But sadly the filter does not manipulate any packet.

        I want to analyse the reaction of VOIP calls to packet loss. So I sent RTP data from one client to another and vice versa. Destination port of client A is 3000 and of Client B it is 3001.
        I tried it with both as hex port value.

        Any idea, why this doesn’t work?
        (Syntax is like any other filter in the w2filterdefs.xml, and the RTP filter is also listed in WANulator)

        • admin says:

          its hard to tell – could you send me a small sample record of the packets (with wireshark or tcpdump -n …) and the filtersetting so I could try to reproduce it here?
          Kind regards,

  11. Gary says:

    Is it possible to define custom bandwidth settings? eg 256Kbit/s etc.

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