SMC Networks SMC6824M manual 127

COMMAND LINE INTERFACE

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”

Example

This example accepts any incoming packets if the source address is within subnet 10.7.1.x. For example, if the rule is matched; i.e., the rule (10.7.1.0 & 255.255.255.0) equals the masked address (10.7.1.2 & 255.255.255.0), the packet passes through.

Console(config-ext-acl)#permit 10.7.1.1 255.255.255.0 any Console(config-ext-acl)#

This allows TCP packets from class C addresses 192.168.1.0 to any destination address when set for destination TCP port 80 (i.e., HTTP).

Console(config-ext-acl)#permit 192.168.1.0 255.255.255.0 any destination-port 80

Console(config-ext-acl)#

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