To use the amateur radio protocols within Linux you will need to get a suitable copy of the AX.25 Utilities. More detailed information about AX.25, NET/ROM and ROSE, associated programs and utilities can be found on http://www.linux-ax25.org.
There is an active mailing list for discussing Linux amateur radio matters called email@example.com. To subscribe to it, send a message to firstname.lastname@example.org with the words "subscribe linux-hams" in the body of the message, the subject field is ignored. You don't need to be subscribed to post but of course that means you might miss an answer.