Note
You are viewing the documentation for an older release of Interworx (6.x). To see documentation for the current generally available release of Interworx, click here: 7.13.
How to Enable Tarpitting to Reduce Spam¶
Tarpitting is when a server identifies a client’s abnormal email operations, and slows down or “tarpits” the process, preventing spam. For more information: https://www.techopedia.com/definition/1722/tarpitting.
With tarpitting enabled, if a sender attempts to issue commands to the mail server before the banner, the connection is dropped:
[root@localhost ~]# telnet test.corp.interworx.com 25
Trying 10.1.16.999...
Connected to test.corp.interworx.com.
Escape character is '^]'
HELO test 554
SMTP protocol violation
Connection closed by foreign host.
Set Up:¶
To enable tarpitting, follow these steps:
At the command line, use the text editor to view
/etc/tcprules.d/tcp.smtp
. It will look similar to the following:At the end of the line beginning with :allow, add the following:
,GREETDELAY="5",DROP_PRE_GREET="1"
#. Run ~vpopmail/bin/clearopensmtp