Local Network Problem

[Don Henson]

Nils Kassube wrote:
> Don Henson wrote:
>> Eberhard Roloff wrote:
>>> Don Henson wrote:
>>>> To make a long background story short...
>>>>
>>>> In restoring from a major system crash, I ended up with a
>>>> server/workstation, a workstation, and a laptop (wifi) that should
>>>> be talking to each other over Ethernet. The laptop will not respond
>>>> to a ping from anybody and the other two will respond to each
>>>> other's pings if I use the domain address. They will not respond if
>>>> I ping the corresponding IP address. This seems backwards to me but
>>>> that's the way it is. At one point, I had all three machines talking
>>>> but after rebooting all three, the problem returned. I've been
>>>> working on this for a couple of days and now I find myself
>>>> thoroughly confused. I have no idea which files and logs might be
>>>> useful. If you are interested in helping, let me know what data you
>>>> need and I'll post it forthwith. I'd really appreciate a little help
>>>> on this one.
>>>>
>>>> Don Henson
>>> on each one:
>>>
>>> ifconfig eth0
>>> cat /etc/hosts
>>>
>>> then: Do you use a dhcp server for your machines? (For example, your
>>> router could be acting as such a server)
>>>
>>> do you use a firewall on all your machines or on specific machines?
>>>
>>> What does a packet sniffer, ex. ethereal show on your laptop, when
>>> you try to ping it from another machine.
>>>
>>> If you are working with fixed ip addresses, what happes if you
>>> connect only two machines via a crossover cable , i.e. leave out your
>>> swith and anthing else in between.
>>>
>>> kind regards
>>> Eberhard
>> Per your request...
>>
>> For Earth-svr
>> dhenson at Earth-svr:~$ ifconfig
>> eth0      Link encap:Ethernet  HWaddr 00:07:E9:9C:26:0B
>>           inet addr:192.168.1.51  Bcast:192.168.1.255 
>>
>> dhenson at Earth-svr:~$ cat /etc/hosts
>> # 127.0.0.1     localhost
> 
> Please uncomment this entry, although it seems to be unrelated to your 
> problems.

Thanks. I must have looked at that line a hundred times and never
noticed that hashmark.
> 
>> 192.168.1.51    Earth-svr.site  Earth-svr       localhost
> 
> Localhost should be 127.0.0.1 not the address of an external interface. It 
> may work, but I think it is quite unusual.

One of my troubleshooting efforts. Changed back.
> 
>> 192.168.1.52    Venus-ws.site   Venus-ws
>> 192.168.1.53    Mars-laptop.site        Mars-laptop
>>
>> For Venus-ws
>>
>> jhenson at Venus-desktop:~$ ifconfig
>> eth0      Link encap:Ethernet  HWaddr 00:15:F2:5B:9B:10
>>           inet addr:192.168.1.52  Bcast:192.168.1.255 
>>
>> jhenson at Venus-desktop:~$ cat /etc/hosts
>> 127.0.0.1       localhost
>> 192.168.1.51    Earth-svr.site          Earth-svr
>> 192.168.1.52    Venus-ws.site           Venus-ws
>> 192.168.1.53    Mars-laptop.site        Mars-laptop
>>
>> For Mars-laptop
>>
>> dhenson at Mars-laptop:~$ ifconfig
>> eth0      Link encap:Ethernet  HWaddr 00:19:B9:76:09:3C
>>           inet addr:192.168.1.53  Bcast:192.168.1.255 
>>
>> wlan0     Link encap:Ethernet  HWaddr 00:19:7E:62:59:16
>>           inet addr:192.168.1.53  Bcast:192.168.1.255 
> 
> Don't use two interfaces with the same IP address. That can't work. Please 
> note: An IP address defines an interface, not a machine. Probably this is 
> the reason why your laptop can't talk to anybody.

I named the eth0 interface 'Mars-wired' and assigned an ip address of
192.198.1.54.
> 
>> dhenson at Mars-laptop:~$ cat /etc/hosts
>> 127.0.0.1 localhost
>> 192.168.1.51 Earth-svr.site Earth-svr
>> 192.168.1.52 Venus-ws.site Venus-ws
>> 192.168.1.53 Mars-laptop.site Mars-laptop.site
>>
>> The original install used DHCP but I am tryng to switch to static.
>>
>> My Linksys router/switch has a firewall. I use that and my machines
>> have their firewalls turned off.
> 
> I don't see an entry for your router in any of your /etc/hosts files. You 
> should add a line
> 
> 192.168.1.1 router.site router
> 
> to each of the files (I assume it has the address 192.168.1.1). Otherwise 
> you can't talk to the internet.

Added
> 
> What is the output of the route command on your machines? It should look 
> like this:
> 
> Kernel IP routing table
> Destination  Gateway     Genmask         Flags Metric Ref    Use Iface
> 192.168.1.0  *           255.255.255.0   U     0      0        0 eth0
> default      router.site 0.0.0.0         UG    0      0        0 eth0
> 
> The first line defines the local network, so you can talk to the other 
> local machines. These machines can be reached directly without a gateway. 
> The second line defines the rest of the world. To reach any non-local 
> machine the data should be sent to the gateway router.site.

dhenson at Mars-wired:~$ route
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use
Iface
192.168.1.0     *               255.255.255.0   U     0      0        0 eth0
192.168.1.0     *               255.255.255.0   U     0      0        0
wlan0
link-local      *               255.255.0.0     U     1000   0        0 eth0
default         router.site     0.0.0.0         UG    0      0        0
wlan0
default         router.site     0.0.0.0         UG    0      0        0 eth0
dhenson at Mars-wired:~$
> 
> BTW: Why don't you want to use DHCP? It can make life so much easier. If 
> you just don't want to use the built-in DHCP server of the router you 
> could install a DHCP server e.g. on your Earth-svr machine.

I was having problems getting everything to work. Static addressing
*sounded* easier. If I wanted to change back, I would turn on the DHCP
server and change the entries in /etc/network/interfaces to dhcp instead
of static. Are there any other changes I should make?
> 
> 
> Nils
> 
I think I just discovered "THE BIG PROBLEM". When I restarted
networking, '/etc/init.d/networking restart', I got the following response:

> dhenson at Mars-wired:~$ sudo /etc/init.d/networking restart
> Password:
>  * Reconfiguring network interfaces...                                          Error for wireless request "Set Encode" (8B2A) :
>     invalid argument "<my password>".
> mount: can't get address for linux.site
> mount: can't get address for linux.site
> mount: can't get address for linux.site
> mount: can't get address for linux.site
> RTNETLINK answers: File exists
> run-parts: /etc/network/if-up.d/avahi-autoipd exited with return code 2
> mount: can't get address for linux.site
> mount: can't get address for linux.site
> mount: can't get address for linux.site
> mount: can't get address for linux.site
>                                                                          [ OK ]
> dhenson at Mars-wired:~$

I had seen this linux.site error message before but couldn't figure out
where it came from. linux.site was the original name for my server but
was changed to Earth-svr.site early on. Suddenly it hit me. When trying
to set up NFS, I added some (incorrect) lines to /etc/fstab. I checked
and they were still there. I removed those lines and restarted
networking. Only one hopefully minor error reported. This time I got:

> dhenson at Mars-wired:~$ sudo /etc/init.d/networking restart
>  * Reconfiguring network interfaces...
Error for wireless request "Set Encode" (8B2A) :
>     invalid argument "<my password>".
> RTNETLINK answers: File exists
> run-parts: /etc/network/if-up.d/avahi-autoipd exited with return code 2
>                                                                          [ OK ]
> dhenson at Mars-wired:~$ 

Now every machine can ping each other and I still have access to the
Internet. Thanks for your help.

Don Henson