Virtual IPs (VIPs) refer to a situation where an IP address does not correspond to a single physical interface. They are used in many scenarios, including the following:
- NAT (including one-to-many NAT)
- Scenarios where fault tolerance is needed (for example CARP)
- Mobile usage scenarios, which allows a mobile user to maintain a consistent virtual IP address even as their actual IP address changes
To add a VIP, navigate to Firewall | Virtual IPs and click on the Add button at the bottom of the table. pfSense offers four options for virtual IPs:
- IP Alias
- CARP
- Proxy ARP
- Other
Of these four options, we can state the following:
- CARP, Proxy ARP, and Other were available with the earliest versions of pfSense. IP Alias is available with version 2.0 and higher.
- All current options can be used with NAT.
- CARP and IP Alias can be used by the firewall to bind and/or run services...
