Unable to use new network config...

Unable to use new network config...

Post by Steven M Peters » Thu, 03 Sep 1998 04:00:00



We are converting our network over to a higher bandwidth one and in the
process we were issued new IPs, gateway, nameservers, etc.  My problem is
that the new IP address will not work even though it is supposed to be
working and for all I can tell, I have it set up ok.  The old IP address
worked fine with the machine, but now they cut out the old network and we
are now on the new network.  I went into /etc/rc.d/rc.inet1 and changed
the network configuration, but it still won't work.  99% of the other
machines on the network all are win95 machines and they all work fine, but
for some reason I can't get the linux server to work with its new IP.

I was wondering if I need to enable new protocols or something with this
new network.  Has anyone else had a problem like this?  I've tried
switching Ips with the working win95 machines and it still doesn't work.
I tried moving the computer to a new network port and that didn't work
either.  The only thing abnormal I noticed about the whole configuration
was that the gateway address for my IP is 209.250.192.1 and my IP address
is 209.250.195.11.  The windows machiens seem to think this is fine, but
the linux server doesn't like the differing subnets(?).  I would
appreciate any help as this machine is used by my professors for their
classes which started yesterday (ack!).  I'd like to get it working for
them ASAP.  Here is some info about my system:

IP= 209.250.195.11
Gateway= 209.250.192.1
Subnet Mask= 255.255.248.0
Nameservers: 209.250.192.3
               209.250.223.15

Linux 2.0.35 using a 3c509 NIC

If you need more info let me know.

Symtoms:
Unable to ping anything on local network or internet
Unable to ping gateway
Can ping myself.
If I steal someones IP on the local network while their computer is
    using it, Their computer complains about the conflict and even
    displays the hardware address of the machine that took it.  Yet, my
    linux machine can not otherwise be reached.

Sten

 
 
 

Unable to use new network config...

Post by Juergen P. Mei » Thu, 03 Sep 1998 04:00:00



The most immediate problem you have is the non-standard Subnet
with a mask of  255.255.248.0
This contains the 8 Class C nets 209.250.192.0 to 209.250.199.0
and makes em a common Subnet. (8 * 254 hosts)
You have to take care that the netmask is 255.255.248.0, the
networkaddress is  209.250.192.0 and the Broadcast address is
209.250.199.255.

AFAIK the combination of 209.250.x.x nets into a 11 bit subnet
is not valid according to the RFC's, but i might be wrong ;-)
Ask your Sysadmin why (s)he chose to do this... (S)he might know
more than we ;-)

If you have a RedHat System, you need to change the following files:
/etc/hosts
/etc/sysconfig/network
/etc/sysconfig/network-scripts/ifcfg-eth0

You may also need to change named, routed, httpd, dhcpd and other
daemon config files if you use any of them.

Note: until RedHat5.1 there were several bugs in the Graphical
Configuration tool which prevented one from changing the ip-address
of a redhat host. (unless (s)he edited the above 3 file manually).

If you have a different Linux (SUSE, Caldera, Slackware, etc) the
names and locations of the files might differ. you may want do to a

# lets say your old ip-address was 192.168.34.56:
(cut&paste the following line into your shell - it may take some time)
find /etc -type f -exec fgrep -Hn 192.168. \{\} \;

and note all files and line-numbers where your old ip was found.
Forget about files ending with ~ or .swp or .orig or .rpm-save
or matching #*#, these are temporary files and backups.

Now replace the old ip with your new one on all these files.

this should work.

To see if your config is ok, issue the follwing commands and see
if the following output (or very similar) happens:

$ route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
209.250.192.0   0.0.0.0         255.255.248.0   U     0      0      587 eth0
127.0.0.0       0.0.0.0         255.0.0.0       U     0      0        8 lo
0.0.0.0         0.0.0.0         209.250.192.1   UG    0      0      202 eth0

$ ifconfig
lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Bcast:127.255.255.255  Mask:255.0.0.0
          UP BROADCAST LOOPBACK RUNNING  MTU:3584  Metric:1
          RX packets:31757 errors:0 dropped:0 overruns:0
          TX packets:31757 errors:0 dropped:0 overruns:0

eth0      Link encap:Ethernet  HWaddr 00:00:AA:BB:CC:DD
          inet addr:209.250.195.11  Bcast:209.250.199.255  Mask:255.255.248.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:27222996 errors:0 dropped:0 overruns:0
          TX packets:540756 errors:0 dropped:0 overruns:0
          Interrupt:11 Base address:0xd000
# HWaddr is different for you, and RX, TX, IRQ and Base address
# but the ip-addresses _should_ match !
$ cat /etc/hosts
127.0.0.1               localhost localhost.localdomain
209.250.195.11          myself.our.domain.com   myself
209.250.195.1           mygateway.our.domain.com        mygateway
$ cat /etc/resolv.conf
search our.domain.com
nameserver 209.250.192.3
nameserver 209.250.223.15

Quote:> We are converting our network over to a higher bandwidth one and in the
> process we were issued new IPs, gateway, nameservers, etc.  My problem is
> that the new IP address will not work even though it is supposed to be
> working and for all I can tell, I have it set up ok.  The old IP address
> worked fine with the machine, but now they cut out the old network and we
> are now on the new network.  I went into /etc/rc.d/rc.inet1 and changed
> the network configuration, but it still won't work.  99% of the other
> machines on the network all are win95 machines and they all work fine, but
> for some reason I can't get the linux server to work with its new IP.

> I was wondering if I need to enable new protocols or something with this
> new network.  Has anyone else had a problem like this?  I've tried
> switching Ips with the working win95 machines and it still doesn't work.
> I tried moving the computer to a new network port and that didn't work
> either.  The only thing abnormal I noticed about the whole configuration
> was that the gateway address for my IP is 209.250.192.1 and my IP address
> is 209.250.195.11.  The windows machiens seem to think this is fine, but

this is ok with the subnet-mask 255.255.248.0

- Show quoted text -

> the linux server doesn't like the differing subnets(?).  I would
> appreciate any help as this machine is used by my professors for their
> classes which started yesterday (ack!).  I'd like to get it working for
> them ASAP.  Here is some info about my system:

> IP= 209.250.195.11
> Gateway= 209.250.192.1
> Subnet Mask= 255.255.248.0
> Nameservers: 209.250.192.3
>                209.250.223.15

> Linux 2.0.35 using a 3c509 NIC

> If you need more info let me know.

> Symtoms:
> Unable to ping anything on local network or internet
> Unable to ping gateway
> Can ping myself.
> If I steal someones IP on the local network while their computer is
>     using it, Their computer complains about the conflict and even
>     displays the hardware address of the machine that took it.  Yet, my
>     linux machine can not otherwise be reached.

> Sten


--
Juergen P. Meier
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