spamd flooded, problem solved [was: Re: : : : Zombie Network Spam Attack]

2008-03-03 Thread Raimo Niskanen
Top posting, for the archives... Problem probably solved. There has been a new spam backscatter flood, and this time it had no impact on my server's network connectivity. Spamd did just fine. It now runs with the flags -B 300 -c 400 -S 30 -s 3 (among others) and they brought down the network load

Re: : Zombie Network Spam Attack

2008-02-11 Thread Calomel
On Mon, Feb 11, 2008 at 11:17:35AM +0100, Raimo Niskanen wrote: On Fri, Feb 08, 2008 at 11:20:31AM -0500, Calomel wrote: Raimo, Can you use the spamd.alloweddomains to whitelist email addresses and domains you accept mail for? Any email sent to your mail server that is not on the list will

Re: : : Zombie Network Spam Attack

2008-02-11 Thread Chris Smith
On Monday 11 February 2008, Raimo Niskanen wrote: 'Mail From: ' One of several that will put you on the http://rfc-ignorant.org/ blacklist. -- Chris

Re: : Zombie Network Spam Attack

2008-02-11 Thread Raimo Niskanen
On Fri, Feb 08, 2008 at 11:20:31AM -0500, Calomel wrote: Raimo, Can you use the spamd.alloweddomains to whitelist email addresses and domains you accept mail for? Any email sent to your mail server that is not on the list will only goto spamd and never get the chance to be

Re: : : Zombie Network Spam Attack

2008-02-11 Thread Raimo Niskanen
On Fri, Feb 08, 2008 at 11:19:06AM -0500, Dave Anderson wrote: On Fri, 8 Feb 2008, Raimo Niskanen wrote: Now I am trying to improve the Greyscanner. I noticed it did not trap hosts using an empty envelope sender, unless there were more than one entry from that host. I regarded it as a bug

Re: : Zombie Network Spam Attack

2008-02-09 Thread Peter N. M. Hansteen
Raimo Niskanen [EMAIL PROTECTED] writes: What does lsof -ni:spamd | wc -l say during the peaks? On my machine spamd ran out of sockets (about 670). Depending on the exact properties of the traffic you may get some mileage out of using state tracking options to limit the number of simultaneous

Re: Zombie Network Spam Attack

2008-02-09 Thread ropers
On 08/02/2008, Raimo Niskanen [EMAIL PROTECTED] wrote: Can spamd do anything about zombie hosts? They behave like normal MTAs so they will pass spamd's behavioural tests, right? I don't think most zombies behave like ordinary hosts. Well, it depends on what you mean by zombie. If someone runs

Re: Zombie Network Spam Attack

2008-02-08 Thread Rod Whitworth
On Fri, 8 Feb 2008 11:07:15 +0100, Raimo Niskanen wrote: Apparently we (our mail server) got targeted by a zombie network since suddenly there were some 3 hosts on spamd's whitelist, continously some 600 connections to spamd, and only mails to unknown users coming in. The network connection

Zombie Network Spam Attack

2008-02-08 Thread Raimo Niskanen
Apparently we (our mail server) got targeted by a zombie network since suddenly there were some 3 hosts on spamd's whitelist, continously some 600 connections to spamd, and only mails to unknown users coming in. The network connection was flooded, the web server sluggish, downloads creeped,

Re: : Zombie Network Spam Attack

2008-02-08 Thread Raimo Niskanen
On Fri, Feb 08, 2008 at 10:08:19PM +1100, Rod Whitworth wrote: On Fri, 8 Feb 2008 11:07:15 +0100, Raimo Niskanen wrote: : : * To make the greylist herustics validate the hosts by reverse DNS PTR lookup and then forward A lookup is apparetly a debatable issue according to the current

Re: : Zombie Network Spam Attack

2008-02-08 Thread Raimo Niskanen
On Fri, Feb 08, 2008 at 12:33:47PM +0100, Peter N. M. Hansteen wrote: Raimo Niskanen [EMAIL PROTECTED] writes: Apparently we (our mail server) got targeted by a zombie network since suddenly there were some 3 hosts on spamd's whitelist, continously some 600 connections to spamd, and

Re: : Zombie Network Spam Attack

2008-02-08 Thread Dave Anderson
On Fri, 8 Feb 2008, Raimo Niskanen wrote: Now I am trying to improve the Greyscanner. I noticed it did not trap hosts using an empty envelope sender, unless there were more than one entry from that host. I regarded it as a bug and fixed it. I hope an empty envelope sender really is suspicious or

Re: Zombie Network Spam Attack

2008-02-08 Thread Calomel
Raimo, Can you use the spamd.alloweddomains to whitelist email addresses and domains you accept mail for? Any email sent to your mail server that is not on the list will only goto spamd and never get the chance to be greylisted/whitelisted. Then you could write a simple script to look through the

Re: : Zombie Network Spam Attack

2008-02-08 Thread Dave Anderson
On Fri, 8 Feb 2008, Peter N. M. Hansteen wrote: Raimo Niskanen [EMAIL PROTECTED] writes: If a backscatter gets through to sendmail, and it is to an invalid user, what is the proper thing for sendmail to do? My sendmail most probably does the default, which I guess is to bounce the mail. yes,

Re: : Zombie Network Spam Attack

2008-02-08 Thread Peter N. M. Hansteen
Raimo Niskanen [EMAIL PROTECTED] writes: If a backscatter gets through to sendmail, and it is to an invalid user, what is the proper thing for sendmail to do? My sendmail most probably does the default, which I guess is to bounce the mail. yes, if you receive a message intended for a

Re: Zombie Network Spam Attack

2008-02-08 Thread Peter N. M. Hansteen
Raimo Niskanen [EMAIL PROTECTED] writes: Apparently we (our mail server) got targeted by a zombie network since suddenly there were some 3 hosts on spamd's whitelist, continously some 600 connections to spamd, and only mails to unknown users coming in. The network connection was flooded,

Re: : Zombie Network Spam Attack

2008-02-08 Thread Dave Anderson
On Fri, 8 Feb 2008, Stuart Henderson wrote: On 2008/02/08 11:35, Dave Anderson wrote: On Fri, 8 Feb 2008, Peter N. M. Hansteen wrote: Raimo Niskanen [EMAIL PROTECTED] writes: If a backscatter gets through to sendmail, and it is to an invalid user, what is the proper thing for sendmail to

Re: : Zombie Network Spam Attack

2008-02-08 Thread Stuart Henderson
On 2008/02/08 11:35, Dave Anderson wrote: On Fri, 8 Feb 2008, Peter N. M. Hansteen wrote: Raimo Niskanen [EMAIL PROTECTED] writes: If a backscatter gets through to sendmail, and it is to an invalid user, what is the proper thing for sendmail to do? My sendmail most probably does the

Re: : Zombie Network Spam Attack

2008-02-08 Thread Rod Whitworth
On Fri, 8 Feb 2008 15:36:01 +0100, Raimo Niskanen wrote: On Fri, Feb 08, 2008 at 10:08:19PM +1100, Rod Whitworth wrote: On Fri, 8 Feb 2008 11:07:15 +0100, Raimo Niskanen wrote: : : * To make the greylist herustics validate the hosts by reverse DNS PTR lookup and then forward A lookup is