Packeting filtering firewalls are devices that enforce administrative security policies by filtering incoming traffic as well as outgoing traffic based on rules that can include the source and/or destination addresses.
“Outgoing data packets” is incorrect. Firewalls filter incoming as well as outgoing traffic. This is sometimes called Egress and Ingress filtering.
“Incoming data packets only” is incorrect. (see previous explantion)
“User data packet” is incorrect. A packet filtering firewall does not typicallly look into the data portion of the packet.
References CBK, p. 464 AIO3, pp. 482 -484