Is there an easy way to add extra commands to iPXE? I'd really like to extend it in a few ways in order to provide more host data to boot scripts. Tcpdump is one of the commands I'd like to add. How difficult would this be to accomplish?
Depends of the functionality behind the command. It all needs to be re-implemented in the ipxe context which is quite specific.
tcpdump is quite complex. It almost always boils down to what you want to do, and the reason for it. maybe there is a better way?
Do you really need this in iPXE, or would for example an minimal linux do the same just as well?