Massbind is a small convenience lib to handle large range of ip6 subnet addresses (/64 or smaller) and add (or delete) ip6 addresses to a given interface. The ip6 addresses may be picked in a range or randomly.

Linux only.

In certain situations is useful to bind to more than one ip address at client or server side. In order to bind to the address, it first has to be added to the interface. At IPv4 times, you were lucky if you had a subnet with some dozen of unused IP's you could assign by hand. With IPv6 you usually get a /64 subnet from your provider/hoster. You can't add addresses by hand any longer. Using massbind, you can pick a dedicated ip6 address for each connection within your program and throw it away after usage.

Note that massbind will actually only add the address to the given interface, you need to bind() to it by yourself program-wise in order to bind to the correct (src:srcport, dst:dstport) tuple.

You could use ip6 privacy extensions, but this is not fine grained enough to pick one address per connection. You may also use IP_TRANSPARENT sockets to bind to non-exsiting addresses and setup your netfilter rules accordingly.

Server-side you can also add an entire subnet to your interface and add routes to the local routing table:

# ip -6 addr add 2019::/64 dev eth0
# ip -6 route add local 2019::/64 dev lo
# ip -6 route list table local
[...]

And add a route on your border router to reach 2019::/64 via a real ip6 address of that machine. This however makes the entire subnet range accessible from outside. With massbind you can be more picky on the addresses you use and dispose at runtime from within your scanning-engine or whatever use-case you have.

Example code is in mass.c, simply type make. It's straight forward to init and add/del the addresses at hand.

The lib will not filter special addresses. So you may get ...:ffff or similar when walking a range. You either filter these by yourself or write your code to handle errors during mb_add6() gracefully.

The lib is using the routing sockets to add/del addresses directly. You do not need to install libnl or similar. The rtnetlink API should be stable enough to work among various Linux kernel versions 3.x, 4.x.

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