The packet filter language syntax is as follows. Keywords are in bold. Optional terms are in
[square brackets]. Placeholders for literals are in
<angle brackets>. Binary logical operators associate to the left. All keywords and port aliases should be in lower case.
<len>: Packet length in bytes. Greater or less comparison is inclusive of
<mac_addr>: MAC address, e.g.
DE:AD:BE:EF:D0:0D. Hex digits are case-insensitive.
<ip_addr>: IP address consistent with the IP version specified previously. E.g.
<port_lst>: List of ports or port ranges separated by commas, e.g.
13,ssh,6000-7000,20. The following aliases for defined ports and port ranges can be used as an item in the list, but not as part of a range (
|Alias | Port(s) |
53 | |
7 | |
20 | |
21 | |
80 | |
443 | |
194 | |
123 | |
115 | |
22 | |
23 | |
69 | |
dbglog | Netboot debug log port | |
dbgack | Netboot debug log ack port|
The following aliases may be used instead of the keywords listed in the syntax: