US Robotics NETServer/8 Manual do Utilizador descarregar pdf (Página 173)

Packet Filters 8-21

IP:

010 ACCEPT src-addr = 192.77.200.203/16;

The following rule example prevents forwarding of IP packets

with destination addresses that match the first 16 bits of the

given IP address (that is, addresses beginning with 188.39):

IP:

010 REJECT dst-addr = 188.39.150.166/16;

The following rule example allows forwarding of IP packets

with source address 192.77.100.32 and destination address

201.128.11.34:

IP:

010 AND src-addr = 192.77.100.32;

020 ACCEPT dst-addr = 201.128.11.34;

Masks

These fields specify the number of bits to be used in the source

address and destination address comparisons. Valid values are:

0 Match packets with any IP address. The contents of the

source address or destination address field are not important.

8 Compare the first byte (octet) in the IP addresses.

16 Compare only the first two bytes of the IP addresses

24 Compare only the first three bytes of the IP Addresses

32 Match the entire IP address (this value can be omitted)

The masks are separated from source address and destination

address by forward slashes (/).

TCP and UDP Parameter Filtering

TCP and UDP packets are typically sent from and destined for

standard port numbers that provide common network services,

such as Domain Name Service, SNMP, and Telnet. You can

filter TCP and UDP packets by source and destination ports by

defining filter rules that compare the port number in a TCP or

UDP packet to a specific value.

The following rule example accepts only TCP packets that have

a source port number of 24 or greater.

1 2 ... 168 169 170 171 172 173 174 175 176 177 178 ... 300 301

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US Robotics NETServer/8 Manual do Utilizador Página 173