====== Kernel netdump project ======

Status: [[https://svnweb.freebsd.org/changeset/base/333283|Committed to SVN in r333283]] and nearby commits.

Netdump provides kernel core dumping over the network, instead of to a
local disk.  It implements a very minimal UDP/IPv4 stack and uses a
custom UDP protocol to transmit the dump to the netdump server running
on another host.

Netdump should find use in diskless workstation clusters, PXE-booted
test machines, and perhaps when doing disk driver development.

  * https://web.archive.org/web/20040619062455/www.cs.duke.edu/~anderson/freebsd/netdump/readme.html

===== Caveats =====

  * Netdump is fairly inefficient in the face of packet loss.  When it misses an ACK, it prints ". ".
  * Netdumpd names cores based on source IP ("vmcore-IP.num") but decryptcore(8) expects a certain convention

===== Enhancement ideas =====

  * Fixing any NIC-specific netdump bugs as they crop up
  * Validate EKCD + netdumps (CEM: I've done some preliminary testing here and it mostly seems to work.  The integration needs a little polish.)
    * (EKCD provides dump privacy, but not integrity nor does it authenticate the client to the server.)
  * Validate compression + netdump (CEM: I've done some preliminary testing here too and it seems ok.  Ditto maybe needing polish.)
  * Improve performance.  Current protocol is not ideal.
  * Investigate using a standard protocol (TFTP?)
  * Handling changing server domain IPs, interface IPs, and routes in some general fashion.
    * DNS resolution at dump time rather than configuration time?
      * Similar class of issue handling changing resolv.conf list
  * IPv6 support
    * L2 address resolution using NDP instead of ARP
    * Something about SLAAC to auto-configure?
  * Client authentication to netdumpd, i.e., solving the netdumpd trivial %%DoS%% problem
  * Multiple servers (fallback?)

===== Resources =====

[[https://man.freebsd.org/cgi/man.cgi?query=netdump&sektion=4&manpath=FreeBSD+12-current|netdump(4)]]
[[https://man.freebsd.org/cgi/man.cgi?query=dumpon&sektion=8&manpath=FreeBSD+12-current|dumpon(8)]]

===== Contacts =====

  * [[MarkJohnston|Mark Johnston]]