Shared Cache

The shared cache must be configured when TUXGUARD Mail Gateway is run in a cluster, it is used to synchronize cache values between the cluster hosts. The cache holds data like valid/invalid users, greylist entries, address books, rate limit tokens etc

Secret

A secret value used to prevent cache poisoning or from multiple clusters from interacting with each other.

Port

The UDP port to use for the Shared Cache. Default is 6920.

Unicast Hosts

A comma separated list of hostnames or IP addresses that the cache updates should be sent to by unicast. This is only necessary if you have cluster nodes on different subnets or if you do not want to use multicast to send the cache updates.

Multicast IP

A multicast IP address (within 224.0.0.0/4) that the cache updates should be sent to.
The cluster nodes will automatically subscribe to this multicast IP and use it to send and receive their cache updates.

Multicast can only be used when the machines are on the same LAN (e.g. same subnet) unless the default gateway router has been expressly configured to forward multicast packets to other subnets

Multicast TTL

The multicast TTL to set on any multicast packets that are sent. This is used only when you have configured your routers to send multicast traffic across subnets and this limits the number of networks the multicast packet will cross before being dropped.

The default is 1 which means that the packets are restricted to the same subnet and will never be forwarded by a router.