Every TCP packet contains a Sequence Number (SYN) and an Acknowledgment Number (ACK). Sophos XG Firewall monitors SYN and ACK numbers within a certain window to ensure that the packet is indeed part of the session. However, certain application and third party vendors use non-RFC methods to verify a packet’s validity or for some other reason a server may send packets with invalid sequence numbers.
Applies to the following Sophos products and versions Sophos Firewall What to do This is a known behavior for the XG Firewall that the traffic will only be logged when the connection is closed. From the logging perspective, the session gets logged on connection destroy event, i.e..
RST – Reset: there is an error, close the session without waiting for response; The XG Firewall implements a connection tracking system (conntrack), this system will follow all TCP sessions through the XG Firewall (as well as certain UDP and ICMP sessions). The XG Firewall will check the data packets for conntrack entries.
10/8/2019 · This article will introduce the basic configuration of IPS in Sophos XG Firewall run version 18 firmware. … Displays the attack type: SYN Flood, UDP Flood, TCP Flood, ICMP Flood and IP Flood. Source. Displays whether source packet control is applied or not. … Drop Session – Terminate entire session instead of scanning all the session …
RST (Reset): Closes the session without waiting for a response. This may be because an unexpected packet was received. XG Firewall checks the data packets for conntrack entries. Conntrack entries are generated when connection initializing packets are sent, for example, TCP, SYN , or ICMP echo requests.
