ECS4100 Series Web Management Guide-R07

Chapter 12 | Security Measures
Access Control Lists
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◆ Action – An ACL can contain any combination of permit or deny rules.
◆ Source/Destination Address Type – Specifies the source or destination IP
address type. Use “Any” to include all possible addresses, “Host” to specify a
specific host address in the Address field, or “IP” to specify a range of addresses
with the Address and Subnet Mask fields. (Options: Any, Host, IP; Default: Any)
◆ Source/Destination IP Address – Source or destination IP address.
◆ Source/Destination Subnet Mask – Subnet mask for source or destination
address. (See the description for Subnet Mask on page 320.)
◆ Source/Destination Port – Source/destination port number for the specified
protocol type. (Range: 0-65535)
◆ Source/Destination Port Bit Mask – Decimal number representing the port
bits to match. (Range: 0-65535)
◆ Protocol – Specifies the protocol type to match as ICMP, TCP, UDP or Others,
where others indicates a specific protocol number (0-255). (Options: ICMP, TCP,
UDP, Others; Default: Others)
The following items are under TCP
■
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:
■
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 bit mask 2
■
Both SYN and ACK valid, use control-code 18, control bit mask 18
■
SYN valid and ACK invalid, use control-code 2, control bit mask 18