ZyXEL Communications USG FLEX H Series User Manual page 427

Make sure you enable Destroy Infected File in the Configuration > Security Service > Anti-Malware
screen to modify infected files before forwarding the files to the user, preventing them from being
executed.
I added a file pattern in the anti-malware allow list, but the Zyxel Device still checks and modifies
files that match this pattern.
Make sure you enable the anti-malware allow list. If it is already enabled, make sure that the allow list
entry corresponding to this file pattern is activated.
The Zyxel Device is not scanning some zipped files.
The Zyxel Device 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 Zyxel Device can concurrently unzip.
The Zyxel Device is deleting some zipped files.
The anti-malware policy may be set to delete zipped files that the Zyxel Device cannot unzip. The Zyxel
Device 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 Zyxel Device can concurrently unzip.
The Zyxel Device's performance seems slower after configuring IPS.
Depending on your network topology and traffic load, binding every packet direction to an IPS profile
may affect the Zyxel Device's performance. You may want to focus IPS scanning on certain traffic
directions such as incoming traffic.
IPS is dropping traffic that matches a rule that says no action should be taken.
The Zyxel Device checks all signatures and continues searching even after a match is found. If two or
more rules have conflicting actions for the same packet, then the Zyxel Device applies the more
restrictive action (reject-both, reject-receiver or reject-sender, drop, none in this order). If a packet
matches a rule for reject-receiver and it also matches a rule for reject-sender, then the Zyxel Device will
reject-both.
The Zyxel Device's performance seems slower after configuring DoS Prevention.
Chapter 29 Troubleshooting
USG FLEX H Series User's Guide
427