More on "VNC works *only* when also connected to internet"

Chris Dillon cdillon "at" wolves.k12.mo.us
Tue, 28 Jul 1998 14:59:26 +0000


On Mon, 27 Jul 1998, Jon Sundquist wrote:

> Some more interesting behavior to follow up on my previous request for
> help.  I reproducibly can start a vnc viewer session on my windows
> machine when the linux machine has  already connected it self to the
> internet.  So I have this set up:
> 
>          Windows box         Linux Box
>          -----------         ---------
> LAN <--> Ethernet card         Modem    <---> ISP
>               +                  +       ppp
>          Serial port  <---> Serial Port
>                        ppp
> 
> (note, the modem is on cua1 and the null modem cable is on ttyS0, aka
> COM2 and COM1, respectively)
> 
> If I start the internet connection first, then I can start VNC.  I
> thought maybe I'd just start it, and then kill the internet connection,
> and maybe it would still work.  Nope.  Vncviewer died (got blank sceen,
> the color of my "xsetroot -solid" in xstartup) with either killing the
> connection to my ISP or even if I just pulled the phone plug (hey I was
> trying everything).  Again, no such limitations occur when I access the
> linux box through a PC X-server.
> 
> I don't know if this adds any more info or not, but I'd really like to
> run vnc rather than the X server.  It is much faster (the X server is
> too slow to really be usable), and lets me run fvwm!
> 
> Jon Sundquist
> 

This isn't a problem with VNC.  I encounter this problem _all_ the
time trying to do other things, and it all boils down to hostname
lookups.  To solve the problem I usually set up a DNS server on the
Unix box (FreeBSD in my case), and give all hosts A and PTR records. 

What is most likely happening is the Linux box is attempting to
perform a in-addr.arpa (PTR) lookup on the remote client before it
allows it to connect and must time-out (about 70 seconds) because it
is also attempting to query the nameservers you have set up in
/etc/resolv.conf (which happen to be out on the Internet).  Have you
tried waiting several minutes to see if anything will happen?  Do you
also encounter this problem with telnet and ftp? 

More than likely in your case you don't need to set up a DNS server,
but can just properly configure /etc/hosts (list all hosts on your
private network) and /etc/host.conf (make sure 'hosts' comes before
'bind').


-- Chris Dillon - cdillon "at" wolves.k12.mo.us - cdillon "at" inter-linc.net
/* FreeBSD: The fastest and most stable server OS on the planet.
   For Intel x86 and compatibles (SPARC and Alpha under development)
   (http://www.freebsd.org)                                         */



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