Eicon Networks DIVA T/A ISDN Modem Guia do Utilizador descarregar pdf (Página 123)

Chapter Nine: Advanced Installations IP filters

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• DNS: Domain name system. Filtering DNS datagrams can cause disruptions in the ability to access

remote sites.

The following options are also available: NFS/RPC, News, Time (NTP), BOOTP, SNMP, ICMP, Ping

(ICMP), Ping Reply, ICMP Redir. For a description of these protocols, consult the appropriate RFC at the

site www.faqs.org.

Activate the filter by clicking the box that appears to the right of the EDIT button.

Click Save. This makes the filter operational.

Note

Unlike other configurations settings, you do not have to reset the DIVA LAN ISDN Modem to make

filters operational.

IP filtering examples

The examples in this section illustrate how to use filters to:

• Dropping incoming traffic from a specific network

• Allowing incoming traffic only from a specific network

• Blocking web surfing

Note

These examples assume that you have not enabled remote management. If enabled, the default filter

stack you see will only contain the single filter: “Forward all datagrams being sent from anywhere that contain

any protocol.“ If no filters are present, the only visible filter will be "Drop All". The "Forward all" filter is

active but invisible.

Dropping incoming traffic from a specific network

This example defines a filter to make sure that no traffic is accepted from a specific network. Assume the

network has the IP address 213.112.12.0.

Since the filter is applied against data from the Internet, it is defined for the ISP profile. Place this filter in the

third position in the stack.

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Eicon Networks DIVA T/A ISDN Modem Guia do Utilizador Página 123