John Borwick’s blog

Windows XP Service Pack 2 (SP2) gave my dad the “access is denied” error. We found a Microsoft suggestion about what to do, but that is really complex and basically involves running the SP2 update, finding which Registry Key can’t be opened, fixing that problem, and then running it again.

Only this forum entry had a more reasonable suggestion: Go to start -> run, then type

secedit /configure /cfg %windir%repairsecsetup.inf /db secsetup.sdb
/verbose

This resets your security policy, so that registry keys that may have given you errors like “Error while opening key” will be reset.

So, I finished TCP/IP Illustrated, Volume 1: The Protocols. Now I’m starting out on TCP/IP Illustrated, Volume 2: The Implementation.

Volume 2 is a code walkthrough of BSD 4.4-Lite, aka Net/3. I love FreeBSD, and one of the reasons I got a Mac was because it’s based on BSD. Well, lo and behold, the fundamental structures described so far (mbufs) are still being used. /usr/include/sys/mbuf.h pointed me to Apple’s Public Source License, though, which threw me off. The FSF says the APSL 2.0 is OK–not perfect, but open enough to be good.

So, here begin my adventures with testing out TCP/IP Illustrated’s code walkthrough using OS X. “netstat -m” is the first cool thing I’ve found out about.

I also went back to the 1990s by turning on “echo”, “discard”, “chargen”, “daytime” in /etc/inetd.conf. The UDP versions of these services aren’t working for me right now, though.