Copyright (c) 2002 Theo de Raadt. All rights reserved.
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.Dd Dec 18, 2002 .Dt SPAMD 8 .Os .Sh NAME .Nm spamd .Nd spam deferral daemon .Sh SYNOPSIS .Nm spamd .Op Fl 45d .Op Fl r Ar reply .Op Fl c Ar maxcon .Op Fl p Ar port .Sh DESCRIPTION .Nm is a a fake .Xr sendmail 8 Ns -like daemon which absorbs false mail. If the .Xr pf 4 packet filter is configured to redirect port 25 (SMTP) to this daemon, it will attempt to waste the time and resources of the spam sender.
p The options are as follows: l -tag -width Ds
p t Fl 4 Return error code 450 to the spammer. t Fl 5 Return error code 550 to the spammer. t Fl d Debug mode. .Nm does not .Xr fork 2 into the background. t Fl r The SMTP error to return to the spammer, ie 450, 451, 550. This defaults to 450. t Fl c the Maximum number of concurrent connections to allow. t Fl p Specify the port number that .Nm should operate on. .El
p .Nm is designed to be very efficient so that it does not slow down the receiving machine. SPAM is never accepted, but always rejected with either a 450 or 550 error message.
p There are currently two methods that are being used to fight spam. l -enum -offset indent t Block (or slowly block) This works well, the spammers are blocked, and cannot access your hosts services. Unfortunately this does little to combat the problem of spam in general, allowing the spammer to continue to spam others. t Accept & drop via a .Xr sendmail 8 addon. This works well for many sites also. All the mail that is recieved by your host is processed by a set of rules, and the spam is either deleted or flagged for further action. Unfortunately this method can sonsume a considerable amount of your systems resources. .El
p What .Nm does, is to defer the spammers connections. It does this in a manner designed to use as few local resources as possible, while consuming as much of the spammers resources as possible. .Nm replies to the spammers mail with error codes which cause will cause mail to be stored in remote mail queues, taking up disk space, and to be resent multiple times, using network resources.
p .Nm does not follow the pollicy of playing nice with your neighbor. Clients which reach .Nm have already been flagged as being spammers. The only way to combat spam is to remove the senders ability to deliver it. In this case, that means force the delivery of spam to have a very high overhead for the remote relay.
p .Nm is best started from .Xr rc 8 and is used in conjuction with .Xr spamd-setup 8 which proceses a list of spammers addresses, and applies appropriate .Xr pfctl 8 rdr rules.
p .Sh SEE ALSO .Xr spamd-setup 8 , .Xr pfctl 8 .Sh HISTORY The .Nm command appeared in .Tn OpenBSD 3.2.