On Oct 29, Hank Nussbacher <hank@ibm.net.il> wrote:
I have a spammer I am trying to block. He is multihomed to me and ISP X. He has address a.b.c.d from me and address a.b.c.e from ISP X. Users started seeing spams from a.b.c.e and complained to ISP X. He shut off SMTP to the customer but the spamming continued. Turns out the user defaults out to me no matter what, so his address was a.b.c.e when coming out of me. For me that is a spoofed address. I then go to block his spoofed address. User then says, it is a valid address and I have no business blocking his IP addresses, whether he has them from me or ISP X. I then say I'll block SMTP and the user says, "show me one letter from a user on the Internet complaining to you that I am spamming". Since his dns is located elsewhere and since the IP addresses are not mine, the users aren't complaining to me - but to ISP X and perhaps ISP Y (providing him secondary DNS service). All the ISP X & Y attempts to shut out the spam aren't affective due to the multihoming.
Are you under any contractural obligation to transit that IP address? The user in question seems to think you are, but you should check that as well; most contracts that I've seen do not mention multihoming specificially, and this could be the perfect loophole for you to use while you give him the 30 days notice or whatever it takes to disconnect him completely. ********************************************************* J.D. Falk voice: +1-650-482-2840 Supervisor, Network Operations fax: +1-650-482-2844 PRIORI NETWORKS, INC. http://www.priori.net "The People You Know. The People You Trust." *********************************************************