FreeBSD committer oshogbo shows us how to configure a network dump on your FreeBSD server. This process requires two machines, a client and a server, one to collect the dump and the other to dump from. The command dumpon and netdumpd are used to facilitate the dumping process
A network dump might be very useful for collecting kernel crash dumps from embedded machines and machines with a larger amount of RAM then available swap partition size. Besides net dumps we can also try to compress the core dump. However, often this may still not be enough swap to keep whole core dump. In such situation using network dump is a convenient and reliable way for collecting kernel dump.
So, first, let’s talk a little bit about history. The first implementation of the network dumps was implemented around 2000 for the FreeBSD 4.x as a kernel module. The code was implemented in 2010 with the intention of being part of FreeBSD 9.0. However, the code never landed in FreeBSD. Finally, in 2018 with the commit r333283 by Mark Johnston the netdump client code landed in the FreeBSD. Subsequently, many other commitments were then implemented to add support for the different drivers (for example r333289). The first official release of FreeBSD, which support netdump is FreeBSD 12.0.
How to configure a network dump in FreeBSD?: https://oshogbo.vexillium.org/blog/68/