Netopia R310 사용자 설명서

A filter consists of criteria based on packet attributes. A typical filter can match a packet on any one of the 
following attributes:

■

The source IP address (where the packet was sent from)

■

The destination IP address (where the packet is going)

■

The type of higher-layer Internet protocol the packet is carr ying, such as TCP or UDP

A filter can also match a packet’s por t number attributes, but only if the filter’s protocol type is set to TCP or 
UDP, since only those protocols use por t numbers. The filter can be configured to match the following:

■

The source por t number (the por t on the sending host that originated the packet)

■

The destination por t number (the por t on the receiving host that the packet is destined for)

By matching on a por t number, a filter can be applied to selected TCP or UDP ser vices, such as Telnet, FTP, and 
World Wide Web. The tables below show a few common ser vices and their associated por t numbers..

A filter can also use a comparison option to evaluate a packet’s source or destination por t number. The 
comparison options are:

No Compare: No comparison of the por t number specified in the filter with the packet’s por t number.

Not Equal To: For the filter to match, the packet’s por t number cannot equal the por t number specified in the 
filter.

Less Than: For the filter to match, the packet’s por t number must be less than the por t number specified in the 
filter.

Less Than or Equal: For the filter to match, the packet’s por t number must be less than or equal to the por t 
number specified in the filter.

Internet service

TCP port

Internet service

TCP port

FTP

20/21

Finger

79

Telnet

23

World Wide Web

80

SMTP (mail)

25

News

144

Gopher

70

rlogin

513

Internet service

UDP port

Internet service

UDP port

Who Is

43

TFTP

69

World Wide Web

80

who

513

SNMP

161