Host computer configured to facilitate distributed SNAT service

A method of facilitating the provision of a distributed source network address translation (dSNAT) middlebox service for a first network at a dSNAT middlebox service instance executing on a host computer, the method comprising:

• receiving configuration information related to the dSNAT middlebox service, the configuration information comprising (i) a common internet protocol version 4 (IPv4) address used by each instance of the dSNAT middlebox service as a source IP address for data messages sent out of the first network through the dSNAT middlebox service instance and (ii) a range of port numbers assigned to the dSNAT middlebox service instance executing on the host computer;
• identifying, based on the received IPv4 address and the assigned range of port numbers, an IP version 6 (IPv6) address prefix to use to advertise the dSNAT middlebox service instance provided at the host computer;
• and
• advertising, to a gateway device that provides access to networks external to the first network, the identified IPv6 address prefix as reachable at the host computer to direct packets received at the gateway device from an external network using the common IPv4 address and a port number in the range of port numbers assigned to the dSNAT middlebox service instance to the dSNAT middlebox service instance executing on the host computer.