RST stands for reset. RST is one of the TCP flags.
TCP
flags are various types of flag bits present in the TCP header.
Each of them has its own significance. They initiate connections,
carry data, and tear down connections. The commonly used TCP flags
are SYN, ACK, RST, FIN, URG, PSH.
- SYN (synchronize): Packets
that are used to initiate a connection.
- ACK (acknowledgment): Packets that are used to confirm that
the data packets have been received, also used to confirm the initiation
request and tear down requests.
- RST (reset): Signify the connection is down or maybe the service
is not accepting the requests.
- FIN (finish): Indicate that the connection is being torn down.
Both the sender and receiver send the FIN packets to gracefully
terminate the connection.
- PSH (push): Indicate that the incoming data should be passed
on directly to the application instead of getting buffered.
- URG (urgent): Indicate that the data that the packet is carrying
should be processed immediately by the TCP stack.