The basic actions:
ACCEPT - accept packet
DROP - discard packet
QUEUE - forward to application filter
RETURN - continue previous chain
Examples of the extended actions:
CONNMARK - mark connection associated with packet
LOG - log packet and continue packet processing
MARK - mark packet and continue packet processing
MASQUERADE - enable address translation for connection
REDIRECT - deliver packet locally
REJECT - discard packet with notification
ROUTE - apply given routing rules to packet
TARPIT - hold connection associated with packet