automated SMTP server survey
These surveys shall measure which SMTP server software is in real
A reliable source of addresses of mail servers in active use are the
logfiles of the ISP i work for: Only the hosts we succesfully delivered
email to are queried later.
Once a day a script walks through the logfiles and takes the IP addresses
of mailservers we delivered email through. These addresses are compared
to a database to make sure i query them only once a month.
Another script connects to the every host and sends
the following commands:
- EHLO csl18.csl-gmbh.net
- HELO csl18.csl-gmbh.net
- (only in case EHLO was not accepted)
The output is recorded and later analysed by another script. This
script is the weak part of the system: It's far to horrible now.
IP-address of the server, type (or unknown), version (if
recognized) and date are put into a database.
Once a month a list is generated and included here.
Unfortunately the numbers are slightly biased:
- we usually install qmail on our servers and often on customers machines.
- a coworker likes MDaemon on NT.
This service has been discontinued due to time constraints and
trouble with some server admins, resulting in DoS attacks on my
- document server software recognition
- add percentage of EHLO acceptance.
- add counters for common ESMTP extensions.
- add counters for common SMTP protocol implementation errors,
like ending the HELP text with a "-" line.