1 choose standard if you have ip addresses allocated by your isp for each machine that requires access to the internet.
2 choose nat enabled if you want to use a single ip address for accessing the internet, or if you do not have an ip address allocated by your isp for each machine that requires access to the internet.
3 choose nat with dhcp client if you obtain the natpublic ip address from a remote dhcp server.
4 choose nat with pppoe client if you obtain your nat public ip addresses, wan router address and wan and dmz subnet masks from your dsl operator using pppoe.
standard
when you select standard, network address translation (nat) is disabled. all nodes on the lan must use valid public ip addresses. the following information is required.
for the lan settings, specify:
1 internet firewall web address.
this is the ip address that is given to the internet firewall and used to access it for configuration and monitoring. choose a unique ip address from the lan address range.
2 lan subnet mask
this value is used to determine what subnet an ip address belongs to. an ip address has two components, the network address and the host address. for example, consider the ip address 192.168.228.17.
assuming a class c subnet mask of 255.255.255.0 is used, the first three numbers (192.168.228.) represent the class c network address, and the last number (17) identifies a particular host on this network.
for the wan settings, specify:
1 wan router address
wan router address, also called the default gateway, is the address of the router that attaches the lan to the internet.
2 public address
this value is automatically set to the internet firewall web address for the internet firewall.
3 wan/dmz subnet mask
this value is automatically set to the lan subnet mask for the internet firewall.
for the other settings, specify the dns servers. up to three dns servers can be specified, although not all have to be used. the internet firewall uses these servers to look up the addresses of machines used to download the web site filter and for the built-in dns lookup tool.
type the required values and click update to send the configuration data to the internet firewall. it is necessary to restart the internet firewall for these changes to take effect.
nat enabled
network address translation (nat) provides anonymity to machines on the lan by connecting the entire network to the internet using a single ip address. this is useful for two purposes:
1 additional security is provided because all the addresses on the lan are invisible to the outside world.
2 in cases where a network uses invalid ip addresses or if addresses are in short supply, nat can be used to connect the lan to the internet without changing the ip addresses of computers and other devices on the lan.
remote authenticated access is not possible with nat enabled.
when using ip addresses on a lan which have not been assigned by an internet service provider, it is a good idea to use addresses from a special address range allocated for this purpose. the following ip address ranges can be used for private ip networks and do not get routed on the internet:
10.0.0.0 - 10.255.255.255
172.16.0.0 - 172.31.255.255
192.168.0.0 - 192.168.255.255
select nat enabled from the network addressing mode drop-down list if the network uses private ip addresses or if addresses are in short supply. a window similar to that in figure 17 is displayed.
figure 17 network settings window, nat enabled
for the lan settings, specify:
1 internet firewall web address
this is the ip address that is given to the internet firewall lan interface and used to access it for configuration and monitoring. choose a unique ip address from the lan address range.
2 lan subnet mask
this value is used to determine what subnet an ip address belongs to. an ip address has two components, the network address and the host address. for example, consider the ip address 192.168.228.17.
assuming a class c subnet mask of 255.255.255.0 is used, the first three numbers (192.168.228.) represent the class c network address, and the last number (17) identifies a particular host on this network.
for the wan settings, specify:
1 wan router address
wan router address, also called the default gateway, is the address of the router that attaches the lan to the internet.
2 public address
this is the ip address used to access the internet. it will be the only address seen by internet users and all activity on the internet from the lan will seem to originate from this address. this address must be a valid public address and is supplied by the isp.
3 wan/dmz subnet mask
the wan/dmz subnet mask is supplied by the isp.
for the other settings, specify the dns servers. these servers are used by the internet firewall to lookup the addresses of machines used to download the web site filter and for the built-in dns lookup tool.
type the required values and click update to send the configuration data to the internet firewall.
you must restart the internet firewall for these changes to take effect. when computers on the lan are using address ranges not in the same subnet as the nat public ip address, use the internet firewall web address as the default gateway or router address used by these computers to access the internet.
nat with dhcp client
the internet firewall can get its nat public ip address from a remote dhcp server on the wan. when you select nat with dhcp, a window similar to that in figure 18 is displayed.
figure 18 network settings window, nat with dhcp client
for the lan settings, specify:
1 internet firewall web address
this is the ip address that is given to the internet firewall lan interface and used to access it for configuration and monitoring. choose a unique ip address from the lan address range.
2 lan subnet mask
this value is used to determine what subnet an ip address belongs to. an ip address has two components, the network address and the host address. for example, consider the ip address 192.168.228.17. assuming a class c subnet mask of 255.255.255.0 is used, the first three numbers (192.168.228.) represent the class c network address, and the last number (17) identifies a particular host on this network.
for the wan settings, specify:
1 wan router address
wan router address is assigned by the isp's dhcp server.
2 lease expires
this value shows when the ip address lease obtained from the isp dhcp server expires.
3 public address
this is the ip address used to access the internet. it is the only address seen by internet users and all activity on the internet from the lan seems to originate from this address. this value is assigned by the isp's dhcp server.
4 wan/dmz subnet mask
the wan/dmz subnet mask is assigned by the isp's dhcp server.
for the other settings, the dns server addresses are specified by the isp’s dhcp server. the dns servers are used by the internet firewall to look up the addresses of machines used to download the web site filter and for the built-in dns lookup tool.
type the required values and click update to send the configuration data to the internet firewall.
you must restart the internet firewall for these changes to take effect. when computers on the lan are using address ranges not in the same subnet as the nat public ip address, use the internet firewall web address as the default gateway or router address used by these computers to access the internet.
nat with pppoe client
the internet firewall can get its nat public ip addresses, wan router address and wan and dmz subnet masks from your dsl operator using pppoe. you will need to know your username and password for the pppoe server. this information can be obtained from your isp.
figure 19 network settings window, nat with pppoe client
for the lan settings, specify:
1 internet firewall web address
this is the ip address that is given to the internet firewall lan interface and used to access it for configuration and monitoring. choose a unique ip address from the lan address range.
2 lan subnet mask
this value is used to determine what subnet an ip address belongs to. an ip address has two components, the network address and the host address. for example, consider the ip address 192.168.228.17. assuming a class c subnet mask of 255.255.255.0 is used, the first three numbers (192.168.228.) represent the class c network address, and the last number (17) identifies a particular host on this network.
for the isp settings, specify:
1 user name
this is the the user name provided by your isp.
2 password
this is the password provided by your isp.
the wan/dmz and dns settings are specified by the isp’s pppoe server.
the wan/dmz settings show the wan router ip address and the wan ip (nat public) ip addresses allocated to the internet firewall. the dns servers are used by the internet firewall to look up the addresses of machines used to download the web site filter and for the built-in dns lookup tool.
type the required values (that is the user name, password and lan settings) and click update to send the configuration data to the internet firewall.
you must restart the internet firewall for these changes to take effect. when computers on the lan are using address ranges not in the same subnet as the nat public ip address, use the internet firewall web address as the default gateway or router address used by these computers to access the internet.