Let's say that I am connected to a WEP Access Point and I want to sniff all wireless traffic inside that network. How can I decrypt the traffic even though I don't have the cryptographic key?

I found a link that shows how to decrypt live wireless traffic on WEP AP's. http://www.netexpertise.eu/en/linux/crack-wep-key-and-decrypt-live-traffic.html

Edit Cont.: Ok there is extreme confusion. I will explain this once more.

  1. I am connected on a WEP Access Point.
  2. I know the WEP key to the wireless network (Hence, that is why I am connected).
  3. I want to inspect the wireless traffic but it is encrypted.
  4. I want the traffic to be decrypted.
  5. I do not have the cryptographic key.

I don't know where all of the confusion is coming from so I'm going to ask this.

Is the cryptographic key the same as the key that I used to log in to my WEP AP? (xx:xx:xx:xx:xx)

  • 1
    please reword your question to detail what it is you are trying to do. Are you just looking for a howto on WEP decryption? or on how to use wireshark?
    – Rory Alsop
    Commented May 8, 2012 at 23:58
  • how to on WEP decryption. Sorry for not making it clear
    – Backtrack
    Commented May 9, 2012 at 4:18
  • reopened for you - I think the links in @DW's answer have most of what you need
    – Rory Alsop
    Commented May 9, 2012 at 10:10
  • Backtrack, it looks to me like you already answered your own question. It looks like the link you provided in your question answers the question. Did you try it? Did it work for you? What additional information are you missing?
    – D.W.
    Commented May 9, 2012 at 18:02
  • I just edited my question. I will try this today and give feedback on it regarding if it works
    – Backtrack
    Commented May 9, 2012 at 18:23

1 Answer 1


WEP and WPA are different, so I will assume you are asking about WEP. (Ask a separate question if you want to know about WPA.)

Wireshark should be able to decrypt WEP traffic if you have the cryptographic WEP key. For instance, here are instructions for decrypting WEP and WPA traffic.

So all that is needed is a way to find the WEP key. There are several ways to do it:

  1. If you are connected to the WEP network, then your laptop must have the WEP key. So all you need to do is extract it. The way to do this will be OS-dependent, so if this is what you want to know, ask a separate question about how retrieve the WEP key for a wireless network you are connected to, and specify the OS. (e.g., on Linux, iwconfig will show you the WEP key.)

  2. If you are not connected to the WEP network, but want to find the WEP key anyway, there are tools to do this by eavesdropping on a bunch of traffic. I recommend aircrack-ng (see this tutorial on aircrack-ng). Here is a tutorial on using aircrack-ng with Backtrack to recover a WEP key. Or, you could use the link you provided.

WARNING WARNING WARNING: Do not do this without authorization of the owner of the wireless network. Hacking other people's wireless networks without their consent is highly illegal in most countries. Don't do it!

Old information from the previous iteration of the question (you can ignore this):

For WEP, if you only have the password and not the cryptographic key, then you will need to recompute the crypto key from the password. It is computed as a deterministic function, and if you Google for WEP key converter or WEP key calculator you should be able to find utilities that will do the conversion for you. Or, you can just go to your access point's web configuration, and it will usually tell the WEP key (indeed, you could enter in a new passphrase and see the resulting WEP key).

For WPA, you may need to capture the traffic associated with the initial association between the client and the access point (if you just come in later and capture it after the client has already connected to the access point, you may not be able to decrypt).

  • Ok lets say the network is a WEP encryption What password? The password that I used to log in to their network?
    – Backtrack
    Commented May 8, 2012 at 18:52
  • What if I don't have the passwords to decrypt it? Considering someone is doing it Illegaly Is it impossible if I don't have the key?
    – Backtrack
    Commented May 8, 2012 at 18:59
  • @Backtrack, I'm confused. In your question, you said "I have the password". Your latest comments says "What if I don't have the passwords?". This sounds contradictory to me. What am I missing?
    – D.W.
    Commented May 8, 2012 at 20:30
  • P.S. @Backtrack, If you are asking whether it is possible to decrypt wireless traffic without knowing the cryptographic key or password, that's a separate question, and you should ask it separately (make sure to use search first to see if it has been asked before). The short answer is: yes for some kinds of wireless networks, no for others.
    – D.W.
    Commented May 8, 2012 at 20:31
  • 1
    @Backtrack - I don't see that question...I see some other question asking if its possible..with the password..but not without it'
    – Ramhound
    Commented May 9, 2012 at 15:33

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