Netopia R310 사용자 설명서

Proto: The protocol to match. This can be entered as a number (see the table below) or as TCP or UDP if using 
those protocols.

Src. Port: The source por t to match. This is the por t on the sending host that originated the packet.

D. Port: The destination por t to match. This is the por t on the receiving host for which the packet is intended.

On?: Displays Yes when the filter is in effect or No when it is not.

Fwd: Shows whether the filter for wards (Yes) a packet or discards (No) it when there’s a match. 

Returning to our filtering rule example from above (see 

), look at how a rule is translated into a filter. 

Star t with the rule, then fill in the filter’s attributes:

1.

The rule you want to implement as a filter is:

Block all Telnet attempts that originate from the remote host 199.211.211.17.

2.

The host 199.211.211.17 is the source of the Telnet packets you want to block, while the destination 
address is any IP address. How these IP addresses are masked determines what the final match will be, 
although the mask is not displayed in the table that displays the filter sets (you set it when you create the 
filter). In fact, since the mask for the destination IP address is 0.0.0.0, the address for Dest IP Addr could 
have been anything. The mask for Source IP Addr must be 255.255.255.255 since an exact match is 
desired.

■

Source IP Addr = 199.211.211.17

■

Source IP address mask = 255.255.255.255

■

Dest IP Addr = 0.0.0.0

■

Destination IP address mask = 0.0.0.0

Note: To learn about IP addresses and masks, see 

3.

, find the destination por t and protocol numbers (the local Telnet por t):

■

Proto = TCP (or 6)

■

D. Por t = 23

Protocol

Number to use

Full name

N/A

0

Ignores protocol type

ICMP

1

Internet Control Message Protocol

TCP

6

Transmission Control Protocol

UDP

17

User Datagram Protocol