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Community Member

whats a good sniffer?

Can someone recommend a good wireless sniffer for capturing problems after authenticating to the AP? Getting a lot of calls with users login scripts not running or servers not being found. Reboot, and it works just fine. Its like hit and miss, very weird...

10 REPLIES
Community Member

Re: whats a good sniffer?

i use a combination of airmagnet and ethereal, airmagnet to capture the packets and etheral to decode them

http://www.airmagnet.com/

http://www.ethereal.com/

Green

Re: whats a good sniffer?

I use CommView WLAN from TamoSoft (www.tamosoft.com)

It's much less expensive (~US$500.00 for a full license, or $200 for an annual license). They offer a crippled non-timebombed demo version that works with most Atheros-based and Intel-based cards.

AirMagnet and AiroPeek are both thousands of dollars; they have a few more bells & whistles, maybe a little prettier interface ..... but for nuts & bolts capture & analysis, CommView works great.

The issue for any of the wireless "Sniffers" is that the encryption may prevent you from seeing the traffic.

Most can do WEP or WPA-PSK, because you enter the Key value (in the case of WPA-PSK, you need to enter the key, and see the initial exchange with the AP).

If you're using most of the 802.1x / EAP combinations, I don't think any of them can capture, since the key swap and encryption is handled directly between the AP / RADIUS / Host.

Perhaps for diagnostics only, you can set up a WPA-PSK SSID/VLAN so you can watch the authentication and domain login sequences and not suffer too much from the security aspect.

Good Luck

Scott

Community Member

Re: whats a good sniffer?

Hmm yes we use some pretty heavy encryption. I didnt even think of not being able to see the trace logs due to encryption. That definately makes things more difficult. I will check out the Commview, havent heard of that one before... thanks!

Community Member

Re: whats a good sniffer?

I saw your post, and while I don't have any info to provide you on sniffers, I had similar problems. I found that setting GpNetworkStartTimeoutPolicyValue to be long enough for association with the AP and DHCP to go through.

See http://support.microsoft.com/default.aspx?scid=kb;en-us;840669

Community Member

Re: whats a good sniffer?

Well they do get DHCP, its just like finding normal servers either onsite or across the WAN when they log in. They do get logged into the network, just have no drive mappings due to the client not finding the servers.

Its almost like the network cant relay the broadcast messages fast enough through the ip helper command... its weird...

Community Member

Re: whats a good sniffer?

Have you tried defining a WINS server, that will help with Widows shares.

We also had luck with defining the servers entire address, for instance server.domain.local instead of just server. This forced it to be looked up with DNS instead of netbios.

Community Member

Re: whats a good sniffer?

Hmm well we changed out all the login scripts to IP so I guess we will see if that helps, should point to a DNS problem if thats the case, but weird it only affects wireless stuff...

Still would like to get a trace when it happens, but I have no clue how Im going to do that without making a good chunk of my network open to anyone...

Bronze

Re: whats a good sniffer?

omnipeek personal is free and good alternative too ethereal but with wireless support under windows

http://www.wildpackets.com/products/omni/omnipeek_personal/overview

Bronze

Re: whats a good sniffer?

I use Airopeek exclusively now. I have a fully licensed copy, which isn't cheap even with my Cisco employee discount. I mainly use the full version because I can do captures from LWAPP APs. However, the free omnipeek has a lot of the really good features in Airopeek.

Community Member

Re: whats a good sniffer?

I'd be interested in seeing how that works. I don't know that it working necessarily indicates a DNS problem, since your system will use broadcast name resolution first unless you specify a FQDN. Since the wireless network affects broadcast traffic, we found that to be the problem.

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