Web Management Guide

Chapter 11 | Security Measures
Access Control Lists
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Precedence – IP precedence level. (Range: 0-7)
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DSCP – DSCP priority level. (Range: 0-63)
◆ Control Code – Decimal number (representing a bit string) that specifies flag
bits in byte 14 of the TCP header. (Range: 0-63)
◆ Control Code Bit Mask – Decimal number representing the code bits to match.
(Range: 0-63)
The control bit mask 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:
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1 (fin) – Finish
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2 (syn) – Synchronize
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4 (rst) – Reset
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8 (psh) – Push
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16 (ack) – Acknowledgement
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32 (urg) – Urgent pointer
For example, use the code value and mask below to catch packets with the
following flags set:
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SYN flag valid, use control-code 2, control bit mask 2
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Both SYN and ACK valid, use control-code 18, control bit mask 18
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SYN valid and ACK invalid, use control-code 2, control bit mask 18
Web Interface
To add rules to an IPv4 Extended ACL:
1. Click Security, ACL.
2. Select Configure ACL from the Step list.
3. Select Add Rule from the Action list.
4. Select IP Extended from the Type list.
5. Select the name of an ACL from the Name list.
6. Specify the action (i.e., Permit or Deny).
7. Select the address type (Any, Host, or IP).
8. If you select “Host,” enter a specific address. If you select “IP,” enter a subnet
address and the mask for an address range.