use this list to help you create rules.

    1 state the intent of the rule.

    the following are examples of intent for rules:

    2 this rule will restrict all irc access from the lan to the internet.

    3 this rule will allow a remote lotus notes server to synchronize over the internet to an internal notes server.

    4 is the intent of the rule to allow or deny traffic?

    5 what is the flow of the traffic: from the lan to the internet, or from the internet to the lan?

    6 list which ip services will be affected.

    7 list which computers on the lan will be affected.

    8 list which computers on the internet will be affected.

    the more specific, the better. for example, if traffic is being allowed from the internet to the lan, it is better to allow only certain machines on the internet to access the lan.

    once you have defined the logic of the rule, it is critical to consider the security ramifications created by the rule:

    9 will this rule stop lan users from accessing critical resources on the internet?

    for example, if irc is blocked, are there users that require this service?

    10 is it possible to modify the rule to be more specific?

    for example, if irc is blocked for all users, will a rule that blocks just certain users be more effective?

    11 will this rule allow internet users access to resources on the lan in a manner that may create an undue security vulnerability?

    for example, if netbios ports (udp 137, 138, 139) are allowed from the internet to the lan, internet users may be able to connect to pcs with file sharing enabled.

    12 does this rule conflict with any existing rules?

    once you have answered these questions, to add rules you type the information into the correct boxes in the policy rules window.

    a action

    select the allow or deny option button depending on the intent of the rule, as defined by item 2 in the “network access rule logic list” on page 104.

    b service

    from the service menu, select the ip protocol, as defined by item 4 in the “network access rule logic list” on page 104. if the protocol is not listed, it is necessary to first define it in the add service window.

    c source

    there are three parameters to configure for the source item.

    1 select the network access rule’s source port, lan, wan, or dmz, if appropriate, from the ethernet menu.

    2 if there are ip address restrictions on the source of the traffic, such as keeping competitors off the company’s web site, type the starting and ending ip addresses of the range in the addr. range begin and

    addr. range end, respectively.

    3 if all ip addresses are affected, type * in the addr.

    range begin box.