ESET NOD32 ANTIVIRUS - FOR LINUX-BSD MAIL SERVER User Manual

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This chapter describes integration of the NOD32LMS/NOD32BMS with the variety of known email messaging systems.
Knowledge of e-mail messaging system basic principles (gure 4-1) is of paramount importance for understanding of
the NOD32LMS/NOD32BMS operation.
MTA - Mail Transport Agent
A program (for instance sendmail, postx, qmail, exim,
etc.) providing e-mail messages transfer among local and
remote domains.
MDA - Mail Delivery Agent
A program (for instance maildrop, procmail, deliver, local.
mail, etc.) providing delivery of locally addressed e-mail
messages into particular mailboxes.
MUA - Mail User Agent
A program (for instance MS Outlook, Mozilla Mail,
Eudora, etc.) providing access and management of e-mail
messages, i.e. reading, composing, printing etc., stored in
mailboxes.
MAILBOX
A le or a le structure on a disk serving as the storage
space for e-mail messages. Note that there are several
formats of MAILBOX in Linux/BSD OS: an old fashioned
format where e-mails for each user are stored sequentially
in one user appropriate le located in directory ‚/var/spool/mail‘; MBOX (a bit newer but still an old format) with e-mails
stored sequentially in one le located within user home directory; MAILDIR with e-mails stored in a separate les within
a hierarchical directory structure.
The e-mail server receives data communication typically using SMTP - Simple Mail Transfer Protocol communication.
The received message is transferred by MTA either to another remote e-mail messaging system or it is delivered using
local MDA into particular MAILBOX (we assume each local network user owns a MAILBOX located at the server disk).
Note that it is responsibility of the user‘s local MUA to provide download and correct interpretation of the message at
the user’s computer. When retrieving data from MAILBOX the MUA uses typically POP3 - Post Oce Protocol or IMAP
- Internet Message Access Protocol to communicate with the MTA. To send data to the Internet the SMTP protocol
communication is used.
The NOD32LMS/NOD32BMS operating principle is based on data communication interception and scanning at the
various phases of its transfer. The interception locations are marked in the gure 4-1 by symbols S1, S2 and S3.
S1
Scanning of inbound e-mail messages, i.e. messages with the target address corresponding to the destination located
inside the local domain.
S2
Scanning of outbound e-mail messages, i.e. messages bound to some remote Internet domain via its target address.
S3
Bi-directional e-mail messages scanning, i.e. content ltering in MTA.
The rest of this chapter reviews methods of integration of NOD32LMS/NOD32BMS with variety of supported
messaging systems.
NOD32 for Linux/BSD Mail Server
MTA
MDA
Mailbox
MUA
TCP port 25 (SMPT) (SMPT)
e-mail server
S1 PIPE
S3
FILE
S2
TCP port 110 (POP3)
OR 143 (IMAP)
Client
Clients
Computer
TCP port 25 (SMPT)
INTERNET
Figure 4-1. Scheme of UNIX OS e-mail messaging system.

ESET NOD32 ANTIVIRUS - FOR LINUX-BSD MAIL SERVER Specifications

General

Type	Antivirus Software
Supported Operating Systems	Linux, BSD
Email Scanning	Yes
Real-time Protection	Yes
License	Commercial
Purpose	Mail Server Protection
Antivirus Engine	ESET NOD32
Updates	Automatic updates
Management	Remote Management