• Source/Destination Port – Source/destina tion port number for the spe cified
protocol type. (Range: 0-65535)
• Source/Destination Port Bit Mask – Decimal num ber repre sentin g the port bi ts
to match. (Range: 0-65535)
• Control Code – Decimal number (representing a bi t strin g) tha t spe cifie s flag b its
in byte 14 of the TCP header. (Range: 0-63)
• Control Code Bit Mask – Decimal number represen ting the code bi ts to match .
The control bitmask is a decimal number (for an equivalent bina ry bit mas k) t hat is
applied to the control code. Enter a decimal number, where the eq uivalent binar y
bit “1” means to match a bit and “0” means to ignore a bit. The follow ing bits may
be specified:
- 1 (fin) – Finish
- 2 (syn) – Synchronize
- 4 (rst) – Reset
- 8 (psh) – Push
- 16 (ack ) – Acknowledg emen t
- 32 (urg) – Urgent pointer
For example, use the code value and mask below to c atch packet s with the
following flags set:
- SYN flag valid, use control -code 2, cont rol bitmask 2
- Both SYN and ACK valid, use control-code 18, control bitmask 18
- S YN valid and ACK invalid, use contr ol-code 2, control bitma sk 18
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Access Control Lists
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