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Cybersecurity
spam and protection?
Post 31121 by Neo on Friday 1st of November 2002 12:24:58 PM
11-01-2002
Administrator
As I understand the poster, he is not talking about relaying (one problem) he is talking about the "Reply-To" field where spammers are using his valid email address in their spam "Reply-To" field.
This is a common technique by spammers and you can't filter on source address or you could block 'the good guys' (people like you receiving spam).
It is like when a spammer sends me email and my email address is in the 'Reply To' field... I certainly don't like blocking me from myself
and the scenarios go on and on. There are many variations of this spam technique.
However, if the email is being bounced, you can easily filter your server to just blackhole all mail from "mailer-daemon" and similar source addresses from bounced mail. You must examine the mail and set up appropriate filters.
You might find this paper of interest:
http://www.silkroad.com/papers/html/bomb/
the paper describes email bombs, countermeasures and filtering basics.
I'm finding programs like Mailwasher more and more useful: www.mailwasher.net but this gem runs only on MS products; so I queue mail on linux and wash with Mailwasher first thing in the morning (like brushing my teeth) or whenever I've been away for a long time; after washing I read with my standard mail user agent. The developer of Mailwasher is very responsive (Nick) and he has added a couple of features at my request in the past month.
This is a common technique by spammers and you can't filter on source address or you could block 'the good guys' (people like you receiving spam).
It is like when a spammer sends me email and my email address is in the 'Reply To' field... I certainly don't like blocking me from myself
and the scenarios go on and on. There are many variations of this spam technique.However, if the email is being bounced, you can easily filter your server to just blackhole all mail from "mailer-daemon" and similar source addresses from bounced mail. You must examine the mail and set up appropriate filters.
You might find this paper of interest:
http://www.silkroad.com/papers/html/bomb/
the paper describes email bombs, countermeasures and filtering basics.
I'm finding programs like Mailwasher more and more useful: www.mailwasher.net but this gem runs only on MS products; so I queue mail on linux and wash with Mailwasher first thing in the morning (like brushing my teeth) or whenever I've been away for a long time; after washing I read with my standard mail user agent.
The developer of Mailwasher is very responsive (Nick) and he has added a couple of features at my request in the past month. |
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LEARN ABOUT DEBIAN
hmine
HMINE(1) HMINE(1) NAME
hmine - a mail message header analyzer. SYNOPSIS
hmine [-vDa] [FILE] hmine -V DESCRIPTION
hmine reads a mail message from FILE or STDIN and outputs a variety of information found in the message headers. The message is expected in Internet mail format (RFC 821,822,2821,2822 or variations thereof). The body is not inspected. EXIT STATUS
On success, hmine returns 1. In case of a problem, hmine returns zero. OPTIONS
-a Print mailboxes and groups found in various header fields, one per line, preceded by the field name. Actual email addresses are always enclosed in '<' and '>' for easy parsing, ie anything not within these delimiters is not part of an email address. Beware that not every line need contain an email address. -D Debug output. -V Print the program version number and exit. USAGE
An invocation looks like this: % hmine email.txt SOURCE
The source code for the latest version of this program is available at the following locations: http://www.lbreyer.com/gpl.html http://dbacl.sourceforge.net BUGS
At present, hmine parses messages but doesn't output anything useful. AUTHOR
Laird A. Breyer <laird@lbreyer.com> SEE ALSO
dbacl(1), mailcross(1), mailfoot(1), mailinspect(1), mailtoe(1), regex(7) Version 1.12 Bayesian Classification Tools HMINE(1)