Full Disclosure mailing list archives
Re: Block notification / bounce mails (as in DDOS)
From: Michael Gale <michael.gale () bluesuperman com>
Date: Thu, 1 Apr 2004 14:04:02 -0700
Hello, Well if the mail server was a postfix box properly configured on decent hardware you should not be able to get DDOS. I have seem postfix servers handle 10,000 messages an hour (166.6 messages a minute, 2.7 per second), so the TCP connections from the remote servers will most happen for 3days on average because the remote server(s) will most likely keep trying to send the message. So "REJECTING" or "BOUNCING" them will not solve the problem, to solve the problem and the messages can in no way be handled by the Exchange server I would add a filter to DISCARD all messages from "MAILER-DEAMON". Since this is a bounced back message it will most likely be small in size, so rejecting the mail or having your ISP block port 25 at the ISP level is not going to solve the bandwidth problem. Michael. On Thu, 01 Apr 2004 16:05:51 +0200 Security <koen4security () hotmail com> wrote:
Hi, Recently, this question popped up during my job interview <question> What would you do when a spammer uses your mail-address as the "From:" and the mails that are sent by the spammer get all bounced back by legitimated mail-servers to your mailhandlers? All the bounces would return to you - as you are the 'from' (assume a rate of 1.000 a minute) and this traffic would kill your network-connection. You wouldn't be able to receive any mail because your mailserver can no longer handle the load</question> I had a 'Dilbert' reaction in the sense that I couldn't come up with a decent answer (needless to say their impression indicated that I should not expect them to hire me). I could only offer these solutions : * contact my ISP and search for a decent solution * put a notice on our corporate website and indicate that we are no longer available through mail on the old address but have a 'new' temporarily one* try to investigate, through the e-mail headers (allthough they could be fake), from where the original posts are coming and try to contact the isp of that netblock What do you all suggest to this 'seemingly' DDOS-attack (allthough not intended as a DOS)? Greetings, Koen _______________________________________________ Full-Disclosure - We believe in it. Charter: http://lists.netsys.com/full-disclosure-charter.html
-- Hand over the Slackware CD's and back AWAY from the computer, your geek rights have been revoked !!! Michael Gale Slackware user :) Bluesuperman.com _______________________________________________ Full-Disclosure - We believe in it. Charter: http://lists.netsys.com/full-disclosure-charter.html
Current thread:
- RE: Block notification / bounce mails (as in DDOS), (continued)
- RE: Block notification / bounce mails (as in DDOS) Aditya, ALD [Aditya Lalit Deshmukh] (Apr 01)
- Message not available
- Re: Block notification / bounce mails (as in DDOS) Koen (Apr 01)
- Re: Block notification / bounce mails (as in DDOS) Security Administrator (Apr 01)
- Re: Block notification / bounce mails (as in DDOS) Ron DuFresne (Apr 01)
- Re: Block notification / bounce mails (as in DDOS) Exibar (Apr 01)
- Re: Block notification / bounce mails (as in DDOS) Tomasz Konefal (Apr 01)
- Re: Block notification / bounce mails (as in DDOS) Valdis . Kletnieks (Apr 01)
- RE: Block notification / bounce mails (as in DDOS) Aditya, ALD [Aditya Lalit Deshmukh] (Apr 02)
- Message not available
- Re: Block notification / bounce mails (as in DDOS) Koen (Apr 01)
- Re: Block notification / bounce mails (as in DDOS) Michael Gale (Apr 01)
- Re: Block notification / bounce mails (as in DDOS) Michael Gale (Apr 02)
- RE: Block notification / bounce mails (as in DDOS) Jos Osborne (Apr 01)
- Re: Block notification / bounce mails (as in DDOS) Koen (Apr 01)
- RE: Block notification / bounce mails (as in DDOS) Aditya, ALD [Aditya Lalit Deshmukh] (Apr 01)
- RE: Block notification / bounce mails (as in DDOS) Richard Gadsden (Apr 02)
- Re: Block notification / bounce mails (as in DDOS) Valdis . Kletnieks (Apr 02)
- RE: Block notification / bounce mails (as in DDOS) Jos Osborne (Apr 02)