Basic UDP ALG

This ALG performs basic sanity checking on UDP headers. If it finds errors. it generates the following anomaly events and system log messages:

• UDP source or destination port 0
• UDP header length check failed

The UDP ALG performs the following steps:

1. When it receives the first packet, the ALG creates bidirectional flows to accept forward and reverse UDP session traffic.
2. If the session is idle for more than the maximum allowed idle time (the default is 30 seconds), the flows are deleted.
3. ICMP errors are allowed only if there is a flow that matches the selector information specified in the ICMP data.