The SnapGear appliance can utilize IP Masquerading (a simple form of Network Address Translation, or NAT) where users on the local network effectively share a single external IP address. Masquerading allows insiders to get out, without allowing outsiders in. By default, the Internet interface is setup to Masquerade.
Masquerading has the following advantages:
•Added security because machines outside the local network only know the gateway address.
•All machines on the local network can access the Internet using a single ISP account.
•Only one public IP address is used and is shared by all machines on the local network. Each machine has its own private IP address.
SnapGear recommends setting Masquerade on the Internet interface.
Internet Interface Aliases allows the SnapGear appliance to respond to multiple IP addresses on the Internet interface. You must also setup appropriate Incoming Access rules to allow traffic sent to the additional (i.e. aliased) IP addresses to be passed to the local network.
On rare occasions it may be necessary to change the Ethernet hardware or MAC Address of your SnapGear appliance. The MAC address is a globally unique address and is specific to a single SnapGear appliance. It is set by the manufacturer and should not normally be changed. However, you may need to change it if your ISP has configured your ADSL or cable modem to only communicate with a device with a known MAC address.
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