There is a standard for doing RS232 with RJ45 connectors: RS232D

I had found things previously that gave this pinout as "the standard way" but didn't mention that it had a name.

(paging @feld who asked me about this weeks ago)

@kurtm @feld Are you sure? AFAIK RS-232D is simply the “Dth” edition of the RS-232 standard (actually an EIA standard by that point) and recommends just the DB-25 connector. I have a copy somewhere but haven't looked at it in years.

(Also, and very pedantically, it's an FCC 8P8C connector. “RJ45” refers to a particular telephone wiring using it so if it's being used for serial it's not RJ45, as such.)