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Note: Similarities with other NetDefendOS features
The Verify MIME type and Allow/Block Selected Types options work in the
same way for the FTP, POP3 and SMTP ALGs.
• Download File Size Limit - A file size limit can additionally be specified for any single
download (this option is available only for HTTP and SMTP ALG downloads).
The Ordering for HTTP Filtering
HTTP filtering obeys the following processing order and is similar to the order followed by the
SMTP ALG:
1. Whitelist.
2. Blacklist.
3. Web content filtering (if enabled).
4. Anti-virus scanning (if enabled).
As described above, if a URL is found on the whitelist then it will not be blocked if it also found on
the blacklist. If it is enabled, Anti-virus scanning is always applied, even though a URL is
whitelisted.
If it is enabled, Web content filtering is still applied to whitelisted URLs but if instead of blocking,
flagged URLs are only logged. If it is enabled, Anti-virus scanning is always applied, even though a
URL is whitelisted.
Figure 6.2. HTTP ALG Processing Order
Using Wildcards in White and Blacklists
Entries made in the white and blacklists can make use of wildcarding to have a single entry be
6.2.2. The HTTP ALG Chapter 6. Security Mechanisms
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