DDTT20 Apr 2006
Arghh. For weeks now, I've been trying to track down why a couple of XP laptops have had random print jobs drop to the floor. I finally got to the point last week where I could reliably duplicate the problem (print four emails from Outlook in quick succession; only three show up, no error on the printer), and today I spent six hours figuring out where the hell the problem was. (I didn't intend to spend that long, but the combination of vociferous complaints and sheer bull-headedness got to me.)
For no particularly good reason, the laptop in question is set to print to the local HP 4200 using IPP. When I looked at the traffic in Ethereal, I noticed that the failing job had a subtly different response to the print job submission from the printer, and at the end the TCP stream was only closed by the laptop -- the printer ACKed right away but did not FIN its end. Aha! Firmware bug!
The printer repair guy who's been working with me to try and fix this stopped by to take a look, and decided to call HP support. Their response: Don't Do That, Then. Apparently, IPP is a weird protocol to use for a LAN and I should really print to port 9100 like everyone else.
Okay, yes, this worked, and it was a stupid amount of time to spend on this problem. But it irritates me that they weren't interested in (what I think is) a firmware bug, and that I'll never probably never get to the bottom of what was going on. Although I'm pretty sure that the JetDirect card just uses an embedded ARM processor; I could just try looking at the firmware with a disassembler...:-)
In other news, something's going subtly wrong with the WRT54G; the
bridging of OpenVPN's tap0 interface and the external ethernet
interface has stopped working. The internal ethernet interface still
works, and if you SSH in that way and run
ifconfig vlan0 down ;
ifconfig vlan0 up the external interface starts working again. I'm
also having problems with the wireless interface. I suspect the
bridging may be involved there, too, since it's bridged with the
internal ethernet. However, I only have my wife's iBook to test with,
so I can't be sure it's not a problem with that.
And my OpenBSD 3.9 CDs are in. Hurray! Time to finally get this firewall off my desktop machine.