Contents #
The tracking information is made available through the conntrack match extension.
Connection Tracking States #
- ESTABLISHED The connection has already seen packets going in both directions. See
also SEEN_REPLY status.
- INVALID The packet doesn’t belong to any tracked connections.
- NEW The packet is starting a new connection or is part of a
connection that hasn’t yet seen packets in both directions.
- RELATED The packet is starting a new connection, but the new
connection is related to an existing connection (such as the data connection for an FTP transfer).
Connection Tracking Status #
The connection tracking logic maintains three bits of status information associated with each connection. Table bellow con- tains a list of these status codes as they are named in the conntrack match extension (the –ctstatus option).
- ASSURED For TCP connections, indicates the TCP connection setup has been completed. For UDP connections, indicates it looks like a UDP stream to the kernel.
- EXPECTED Indicates the connection was expected.
- SEEN_REPLY Indicates that packets have gone in both directions.