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Cisco Bug: CSCtc32047 - FWM sends RST instead of silently drop packets

Last Modified

Feb 22, 2014

Products (1)

  • Cisco Catalyst 6500 Series Firewall Services Module

Known Affected Releases

4.0(7)

Description (partial)

Symptom:

After upgrade from 4.0.5 to 4.0.7 customer application does not working. Application is trying to establish a new connection to the same 5 tuple just after the closing the identical connection, while FWM is "cleaning up" the previous one. FWM is creating syslog and sending RST in answer on SYN.
After receiving this RST, application stack fails to communicate further. The expected behavior is not to send RST but just silently drop the SYN allowing the TCP stack to overcome this.

Conditions:

Customer has replication software where port mapper gives the same 4 tuple for the new session, and this session tries to establish before the previous identical session was cleaned up on fwm
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