Problems Connecting Laptop To Modem

[Polytropon]

On Tue, 19 Jun 2018 09:58:28 +0800, Erich Dollansky wrote:
> Hi,
> 
> On Mon, 18 Jun 2018 17:30:59 +0000
> B J <va6bmj at gmail.com> wrote:
> 
> > On 6/18/18, Gary Aitken <freebsd at dreamchaser.org> wrote:
> > 
> > <snip>
> > 
> > >> Internet:
> > >> Destination        Gateway            Flags     Netif Expire
> > >> default            192.168.0.1        UGS        fxp0
> > >> 127.0.0.1          link#2             UH          lo0
> > >> 192.168.0.0/24     link#1             U          fxp0
> > >> 192.168.0.12       link#1             UHS         lo0  
> > >
> > > This looks like the routing table for the machine which is not
> > > working, with the default set to 192.168.0.1.  If you run "netstat
> > > -rn" from one of the machines which *is* working (as suggested
> > > above), it should show a default route with the IP address of the
> > > actual router. That is the IP address you need to use on the
> > > machine which is not working.  
> > 
> > I just ran netstat -rn on the FreeBSD tower I'm running now and the
> > default address is identical.  I checked the ISP's webpage for the
> > modem that that's the address it uses as well.
> > 
> > I tinkered with the laptop this past weekend and I found the
> > following:
> > 
> > - the machine won't connect with the modem when even when running a
> > liveCD version of FreeBSD (both 10 and 11)--all attempts to ping a URL
> > failed
> > - the machine updates the file:
> > 
> >  /var/db/dhclient.leases.nfe0
> > 
> > but it doesn't add anything
> > - as a test, I created a backup of that file, deleted the original,
> > and found that the machine will still create and write to it, but
> > doesn't add anything
> > - the last update of that file roughly corresponds to the time and
> > date when I connected that modem
> > 
> > A while ago, I installed FreeBSD 10.x on an old IBM ThinkPad and I was
> > successfully send pings to the same URL as before.
> > 
> > This is becoming interesting....
> > 
> try this:
> 
> route flush
> route add 192.168.0.1
> 
> You can test now.

Try to ping "step by step": first your router by IP, then
a public IP address which definitely will answer (for
example 8.8.8.8), and then something that involves name
resolution (for example www.startpage.com). If name
resolution is a problem, the ISP's DNS (or the DNS you
are using) should be examined (dig / drill).



> If it still does not work, set the network configuration to manual.
> Check with the router what address range is reserved for manual usage.
> If nothing is reserved, reserve a block of 16, 32 or what ever you like
> addresses. Enter one of these addresses into your /etc/rc.conf and try
> again.

It's still not clear (to me) if the router/modem provides DHCP
or not. If it doesn't, manual configuration is needed, but if
it does provide DHCP, this should be used - and investigated
if it doesn't work as expected.



> You also could try to run dhclient manually.

I still suggest running tcpdump (or Wireshark) in parallel
to see the corresponding traffic. If the machine (for unknown
reasons) doesn't get the DHCP handshake right - it needs to
perform the required network traffic and should also update
certain files and interface settings - there is a reason for
it. It would sound strange that a defective network card can
cause this strange kind of behaviour, but it's still possible...


-- 
Polytropon
Magdeburg, Germany
Happy FreeBSD user since 4.0
Andra moi ennepe, Mousa, ...