ISC 2.2 and SLIP have some pretty major problems!

[Karl Denninger]

In article <1990Nov09.011135.18395 at ddsw1.MCS.COM> kdenning at nis.naitc.com (Karl Denninger) writes:
>
>We are having a hell of a time getting this to work.
>
>Here's the deal:
>	We have one machine which has a bunch of Telebit 2500's.  We would
>	like anyone to be able to log in under SL/IP that has the
>	appropriate login id and password.

I have basic functionality (including routing dynamically using gated).
There are a number of problems with the stock setup, which I'll go into in a
moment.

Here's the remaining problems:

>	The problem is twofold:
>		1) The system requires a system name when you set up SL/IP.
>		   The problem, of course, is that I don't KNOW what which 
>		   system will call!  ARGH!  

This is still a problem.  There is a TCP/IP address to set here, and how is
one to know what it will be until the connection is made?  There has to be a
way to do this intelligently... if not, it's time to hack some code...

I >could< tell people to all use the same address.... but then I am limited
to one SLIP connection (I may be limited to one at a time anyway by ISC's
software)

>		2) It also wants a line name (ie: /dev/ttyxx).  Again, what
>		   if I have a bunch of lines on a rotary?!  Grrrrr...

This turns out to be a non-issue... it doesn't really need to know the line
you come in on, or at least I can't see where it actually uses the
information you give it.

However, some problems remain:

1)	/etc/gated doesn't recognize when the interface comes back up after
	a connection is dropped.   This stinks; I want the system to
	automatically reestablish the routing tables (I think this is a
	rational requirement).  As things sit now even a "ifconfig sl0 down"
	followed by "ifconfig sl0 up" doesn't reprime /etc/gated; you have
	to kill and restart it before it will realize that the interface is
	back online.  This is horrible!  It also does NOT happen with the
	"real" interfaces.  An attempt to tell gated that both the real
	ethernet board and the SLIP port were "passive" interfaces failed
	with no diagnostic message (ie: /etc/gated just exits if I do this
	with no indication of why, even in "-t" mode).

	Note that it >does< correctly recognize when the line goes down and
	deletes the routes that were established.  And also note that it
	works as designed with real ethernet boards.

	Having to stop and restart /etc/gated manually everytime I start up
	a SLIP connection makes dynamic routing nearly impossible to deal
	with.

2)	The IP number is a REAL problem.  This is especially bad if I want
	to support more than one SL/IP connection at a time.  Then again, it
	appears that ISC doesn't handle that anyway, so perhaps it's no big
	deal.

3)	sldialup is a horrible botch; I need to redo that.  In addition to
	this, there is no mechanism to check and see whether a connection
	has been idle for any amount of time; that is also needed.  You see,
	if you dial out on a non-modem control port, and the other end hangs
	up on you, sldialup stays "online" forever!  Also, sldialup needs to
	learn how to do locking with UUCP and the like.  Hack time here!

4)	Don't even >think< about starting SLIP if you have the NFS server 
	running (on 2.2); the result of doing this is that none of the 
	programs for NFS register with the portmapper, and you can't export 
	any filesystems!  You can, however, mount filesystems from another
	machine (if you don't mind the nasty messages from the system when
	the registration fails for the server side).  I tried to cheat, and
	disable the slip interface while NFS was being loaded -- this ended 
	with a COMPLETELY locked machine when lockd started.  Without 
	lockd I can get both NFS server functionality and SLIP, however, 
	that leaves me without file locking.  ARGH!

	(Be especially careful if you play with this; one result here was
	that I had to boot from floppy and hack the startup files to get the
	machine to come back up!)

	In line with this, DONT screw up when you configure SL/IP.  If you
	fail to enter a valid IP address or hostname for the SL/IP
	connection, and have NFS started, you'll ALSO end up with a
	permanently locked machine (and much hair-pulling to get it back
	online)

5)	I'd >love< a way to determine when a connection is opened (or tries
	to open) so I can write a little daemon that calls up a given site 
	and starts SL/IP with it.  The uses for this should be obvious.

Does anyone have good (or even bad :-) suggestions?  I really don't want to
dedicate modem(s) and phone lines to this; if I didn't care then I'd just do 
it the easy way and get a PC-based router and perform the connection that
way.  As it is I can't do that.

Is it time to start hacking on the kernel driver(s) for this one?  Does
anyone have the requisite code (or something close) to make this easier than
starting from scratch?  I would think that something that is STREAMS based
would be necessary.

Comments and suggestions welcome...

--
Karl Denninger (karl at ddsw1.MCS.COM, <well-connected>!ddsw1!karl)
Public Access Data Line: [+1 708 808-7300], Voice: [+1 708 808-7200]
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