HP VPN Firewall Appliances Attack Protection Configuration Guide

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SMTP packet content filtering
The SMTP packet content filtering, hereafter referred to as SMTP filtering, provides the following
functions:
• Sender filtering—Filters sender addresses in SMTP requests, to prevent specified senders from
sending emails.
• Receiver filtering—Filters receiver addresses (including recipients and carbon copy or named CC
recipients) in SMTP requests, to prevent internal users from sending emails to the specified receiver
addresses.
• Subject filtering—Filters email subjects in SMTP requests, to prevent users from sending emails that
contain specified subject keywords.
• Body filtering—Filters email bodies in SMTP requests, to prevent users from sending emails that
contain specified body keywords.
• Attachment filtering—Checks the names and contents of the attachments in SMTP requests, to
prevent users from sending emails that carry attachments with specified names or content keywords.
• Illegal command blocking—Blocks SMTP requests that carry illegal command words. Legal
command words considered by content filtering include HELO, EHLO, RSET, QUIT, DATA, NOOP,
HELP, EXPN, TURN, VRFY, SOML, SAML, SEND, MAIL, RCPT, and AUTH.
• Oversize email blocking—Limits the size of the emails from internal users and blocks oversized
emails.
POP3 packet content filtering
The POP3 packet content filtering, hereafter referred to as POP3 filtering, provides the following
functions:
• Sender filtering—Filters sender addresses in POP3 responses, to prevent users from receiving
emails from the specified senders.
• Receiver filtering—Filters receiver addresses (including recipients and CC recipients) in POP3
responses, to block emails that contain the specified receiver addresses.
• Subject filtering—Filters email subjects in POP3 responses, to prevent users from receiving emails
that contain specified subject keywords.
• Body filtering—Filters email bodies in POP3 responses, to prevent users from receiving emails that
contain specified body keywords.
• Attachment filtering—Checks the names and contents of the attachments in POP3 responses, to
prevent users from receiving emails that carry attachments with specified names or content
keywords.
FTP packet content filtering
The FTP packet content filtering, hereafter referred to as FTP filtering, provides the following functions:
• Command word filtering—Blocks FTP requests that carry the specified command words. FTP
command words refer to the command words carried in the FTP requests rather than the command
words in command lines. They include RETR, STOR, APPE, USER, PASS, PORT, PASV, RNFR, RNTO,
DELE, LIST, and QUIT. For example, to upload a file named 123.tx t, you enter command put 123.txt.
In this case, the FTP command word to be filtered is not put but STOR.