Cisco Cisco Web Security Appliance S170 사용자 가이드

If the feature key for the feature you are trying to access (via the web interface) has expired, please 
contact your Cisco representative or support organization.

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When a native FTP request is transparently redirected to the FTP Proxy, it contains no hostname 
information for the FTP server, only its IP address. Because of this, some predefined URL categories 
and Web Reputation Filters that have only hostname information will not match native FTP requests, 
even if the requests are destined for those servers. If you wish to block access to these sites, you must 
create custom URL categories for them using their IP addresses.

If the connection between the FTP Proxy and the FTP server is slow, uploading a large file may take a 
long time, particularly when Cisco Data Security Filters are enabled. This can cause the FTP client to 
time out before the FTP Proxy uploads the entire file and you may get a failed transaction notice. The 
transaction does not fail, however, but continues in the background and will be completed by the FTP 
Proxy.

You can workaround this issue by increasing the appropriate idle timeout value on the FTP client.

FTP clients create a zero byte file on FTP servers when the FTP Proxy blocks an upload due to outbound 
anti-malware scanning.