ZyXEL Communications ZyWALL USG 1000 User Manual page 870

Chapter 56 Troubleshooting
The ZyWALL's performance slowed down after I configured many new application
patrol entries.
The ZyWALL checks the ports and conditions configured in application patrol
entries in the order they appear in the list. While this sequence does not affect the
functionality, you might improve the performance of the ZyWALL by putting more
commonly used ports at the top of the list.
The ZyWALL's anti-virus scanner cleaned an infected file but now I cannot use the
file.
The scanning engine checks the contents of the packets for virus. If a virus
pattern is matched, the ZyWALL removes the infected portion of the file along with
the rest of the file. The un-infected portion of the file before a virus pattern was
matched still goes through. Since the ZyWALL erases the infected portion of the
file before sending it, you may not be able to open the file.
The ZyWALL is not scanning some zipped files.
The ZyWALL cannot unzip password protected ZIP files or a ZIP file within another ZIP file.
There are also limits to the number of ZIP files that the ZyWALL can concurrently unzip.
The ZyWALL is deleting some zipped files.
The anti-virus policy may be set to delete zipped files that the ZyWALL cannot
unzip.
The ZyWALL cannot unzip password protected ZIP files or a ZIP file within another
ZIP file. There are also limits to the number of ZIP files that the ZyWALL can concurrently
unzip.
The ZyWALL's performance seems slower after configuring IDP.
Depending on your network topology and traffic load, binding every packet
direction to an IDP profile may affect the ZyWALL's performance. You may want to
focus IDP scanning on certain traffic directions such as incoming traffic.
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ZyWALL USG 1000 User's Guide