Monitoring TCP Client Closed connection

Nikhil,

 

 

BIG-IP v4 unfortunately does not have the capability to hook actions to events in iRules the same way as v9. In v4 rules are evaluated only when receiving data from the client and only until loadbalancing decision is made (i.e. pool member is selected). So, there is no way how to trigger an action after client closes connection. You may be able to parse the information out of the client data using the tcp_content variable (please refer to the BIG-IP Reference Guide for details). This however switches the connection to so called late-binding mode, which means that connection to the server (pool member) is not established until the rule evaluation terminates. BIG-IP has to buffer all client content received in the meantime. If the client expects certain response from the server before sending the piece of information you are looking for, this won't work because BIG-IP does not send anything to the client (at application layer) in the late-binding phase. Also BIG-IP can buffer only 16KB of data or 64 packets whichever comes first (the packet count does not include the initial TCP handshake).

 

 

iRules in BIG-IP v9 are much more flexible.