in my wisp i have a client have virus
this virus make arp spoofing and mac spofing like net cut
every min the pc infected by virus change it ip and mac to the gateway
i hope to protect my network by adding antivirus or something solve this problem
hi,
i think ur clients infected with arp spoofing r arp attack, first u install the antiarp serveredition in your system and run the program now u can find who are infected clients then u install antiarp stand alone edition in client side ..it’s works surelyyyy..
Dear,
I was also facing the same problem. It is basically a virus, but i have not been able to find any thing about this sort of virus on google, and i also tried allot of Anti-Virus Softwares but no progress. I also tried AntiARP, but i can not purchase it for all the clients on my network as my network consists of about 1000 clients, so at last what i did is that i made a custom application for my self to check and correct the ARP-Cache table of clients, according to what i want.
After the installation of the application. Everything is working perfectly and smoothly. However as i designed this application for my network, so it has some limitations, it only works on particular IP and MAC, and is currently ported only for WinXP. I am working to make it work on a list of IP’s and MAC that can be read from a text file, and also porting it for other versions of Windows OS.
As soon as i will be finish up this application i will let all the guyz know. And will put it up on my web for every one. However it might take some time as my RHCE exam is near and also my University exams are also near 
have to prepare for both.
If any one of you want this app for one IP and MAC and only for WINXP, PM me or mail me. I will customize it for you.
i also experience this problem.. after extensive digging we find the problem was an bad AP that clone IPs from network then anunce that itself is the gateway 
all traffic was redirected to this AP. it also clone mac from network … its very dificult to isoleit it.
this problem can also show from customer routers that lose nat and gone to bridge between wan and lan
I have the same problem, finally what was the solution?