Gigabit Ethernet Switch Management Guide

A CCESS C ONTROL L ISTS
3-65
• Control Bitmask – Decimal number representing the code bits to
match.
The control bitmask is a decimal number (for an equivalent binary bit
mask) that is applied to the control code. Enter a decimal number,
where the equivalent binary bit “1” means to match a bit and “0”
means to ignore a bit. The following bits may be specified:
-1 (fin) – Finish
- 2 (syn) – Synchronize
- 4 (rst) – Reset
-8 (psh) – Push
- 16 (ack) – Acknowledgement
- 32 (urg) – Urgent pointer
For example, use the code value and mask below to catch packets with
the following flags set:
- SYN flag valid, use control-code 2, control bitmask 2
- Both SYN and ACK valid, use control-code 18, control bitmask
18
- SYN valid and ACK invalid, use control-code 2, control bitmask
18