Filter
Top Products
C
OMMAND
L
INE
I
NTERFACE
4-120
Default Setting
None
Command Mode
Extended ACL
Command Usage
• All new rules are appended to the end of the list.
• Address bitmasks are similar to a subnet mask, containing four integers
from 0 to 255, each separated by a period. The binary mask uses 1 bits
to indicate “match” and 0 bits to indicate “ignore.” The bitmask is
bitwise ANDed with the specified source IP address, and then compared
with the address for each IP packet entering the port(s) to which this
ACL has been assigned.
• You can specify both Precedence and ToS in the same rule. However, if
DSCP is used, then neither Precedence nor ToS can be specified.
• The control-code bitmask is a decimal number (representing an
equivalent 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 2”
- Both SYN and ACK valid, use “control-code 18 18”
- SYN valid and ACK invalid, use “control-code 2 18”