I got this note from Allen Garvin, that details his adventure in taking a stock 4.2BSD VAX image, getting it running on SIMH, and turning on the network stack.
Although 4.2 may have had security issues, (R Morris), and had some clear issues with scaling. Along with a whole host of other issues. Naturally if you want something more ‘robust’ on modern networks, you’ll want 4.3BSD which corrected quite a number of issues.
You can read about it over on his blog. It’s very good with step by step instructions, goes over retrieving the NIC driver, re-building the kernel, and getting it operational on our LAN.