13 lines
911 B
Text
13 lines
911 B
Text
Tarpits like spamd are fake SMTP servers, which accept connections but don't
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deliver mail. Instead, they keep the connections open and reply very slowly.
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If the peer is patient enough to actually complete the SMTP dialogue (which
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will take ten minutes or more), the tarpit returns a 'temporary error' code
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(4xx), which indicates that the mail could not be delivered successfully and
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that the sender should keep the mail in his queue and retry again later.
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If the spammer does, the same procedure repeats. Until, after several attempts,
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wasting both his queue space and socket handles for several days, the spammer
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gives up. The resources the spamd server has to waste to do this are minimal.
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If the sender is badly configured, an uncooperative recipient might actually
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delay his entire queue handling for several minutes each time he connects to
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the tarpit. And many spammers use badly configured open relays.
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