Problems Connecting Laptop To Modem
va6bmj at gmail.com
Fri Jun 15 22:08:21 UTC 2018
> From your netstat output (later on), it seems that you
> connect to 192.168.0.1, so if this really is the IP of
> one of your machines, there's a big problem with your
> current configuration.
> At the moment, it doesn't look like a hardware issue.
The laptop is second-hand. It was in rough shape when I got it from
the previous owners so I'm thinking that there might be an on-board
hardware malfunction. It might be the hard drive as it didn't want to
boot at first because of, if I remember correctly, some corrupted
I have some extra HDs on hand. I might try swapping one of those with
the one that's in the machine, installing FreeBSD, and then seeing if
I get the same problem.
Since the laptop's not essential to what I do at home, I may as well
have a bit of fun with it, right?
> My suggestion:
> Take a machine that properly connects to your modem/router and
> gains Internet access this way as desired. Collect information
> about which values exist on your network. Don't guess values. :-)
> The following commands should work on FreeBSD and Linux:
> # arp -a
> # netstat -rn
> # ifconfig -a
> (depending on Linux, the "ip" program has to be used instead)
> Even though it might sound stupid, use pen & paper to make a
> small diagram of your network. Write down the IPs and other
> elements of the configuration.
> If you have a Linux live system connecting without any further
> configuration, it's quite possible you have a DHCP server in
> your modem/router running. In that case, don't try to configure
> things manually, it will just interfere with this mechanism.
> Instead, use
> in /etc/rc.conf. A variation is
> Check /etc/rc.conf for duplicate entries. The _last_ entry
> of the same kind will be in effect, as it's basically just
> a shell script with assignments to shell variables.
> Of course you need to specify the default router address, but
> don't guess it - determine it from a different system. If it
> is the _default_ address that your modem/router uses (and you
> didn't change it), maybe consult its documentation, the address
> should be listed there. It can be things like 192.168.0.1,
> 192.168.1.1, 192.168.178.1, who knows.
> Check if HDCP populated /etc/resolv.conf. In many settings,
> the modem/router will also be a nameserver (even if it just
> "relays" your queries and the replies). This means: The IP
> you're seeing there is the IP of your modem/router.
> In worst case, don't configure anything in /etc/rc.conf and do
> a little experimentation. Run a tcpdump (or maybe Wireshark,
> ex Ethereal) on your network interface and then do all the steps
> manually: Configure the interface, set default routing, try to
> obtain an IP via DHCP (using dhclient), and see it /etc/resolv.conf
> gets populated (which DHCP should fill with the correct values).
> Then try to ping internally with IP, extermally with IP, try to
> resolve a hostname, ping it, open a browser for a HTTP connection,
> and so on. Monitor what you're doing as initially mentioned (to
> see if you actually _see_ what you expect, like ARP messages,
> a DHCP handshake, ICMP pings, and HTTP traffic). If this all
> works, make the settings permanent - even if you only verified
> that using DHCP was the correct thing to begin with. :-)
> Good luck!
> "Trial & error" is not a programming concept. ;-)
I've been writing code off and on for more than 40 years, going back
to the days of WATFOR and WATFIV. Trial-and-error programming helped
me finish my B. Sc.
Thanks to everyone for all the advice and information.
Two things have come from this. One is that I finally set up my tower
machines so that the systems on them are now nearly identical to what
I have on my laptop. I've been meaning to do this for years but I had
little incentive to do so.
The second one is that I'm learning something about networking, which
should help me with what I have at home.
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