ipip - 1.1.11 main

This daemon provides an alternative to the kernel-resident support for IP
encapsulation links. It is better suited for situations where there are many
encapsulation connections to be managed, such as is the case for amateur
radio interconnection of network 44. Also, because the daemon is outside the
kernel, it provides an excellent environment for experimenting with alternate
mechanisms for distributing encapsulation routing updates.
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If you need one encapsulation link, use the kernel's built-in support. If
you need a lot of encapsulation links, give this daemon a try.