That sounds rather odd (not being able to disable auth). I can't say I've ever heard of such a thing.
The NSLU2 is rather limited in what it allows the end user to configure. It insists on asking for a user name/password for any access. Failed logongs are supposed to default to the "guest" account.
Not sure what you're asking about pausing since your httpd returns 401 and PXELINUX's HTTP client likely treats it the same as a 404.
At the PXE boot menu, when I select an entry from the menu and press Enter, I need to see the response/error message before PXE returns to the menu (assuming a boot failure occures, which it does when trying an http boot). As it is, I see just the briefest flash of a message and then it is gone and the menu is active again.
To my knowledge, correct. There is no directive for it. I also doubt that inserting username/password into the URL the standard manner will do anything but return a complete failure. I'll try to see if I can get a quick test set up.
I appreciate that.
You can easily use gPXE/iPXE to provide HTTP access instead of using lpxelinux.0 and it could do authentication.
I am currently trying that. So far I just replaced lpxelinux.0 with undionly.kpxe (in udhcpd.conf) per the ipxe setup instructions. I get the ipxe boot screen and can Ctrl-b to break out of the endless loop (again, per the instructions). I have not gotten any further yet, still reading. I was hoping that it would run the 'default' menu by default but it looks like I have to do some more configuration to get to that point.