Networking Forums

Networking Forums > Computer Networking > Linux Networking > Can't ping subnet but the world is ok

Reply
Thread Tools Display Modes

Can't ping subnet but the world is ok

 
 
Axier
Guest
Posts: n/a

 
      09-07-2003, 08:58 AM
Guys,

I am trying to figure this out. It is a little problematic for me to
experiment too much with the network adapters since I am sitting
remote and
have already driven down to the servers to console into them to
correct a few mistakes a couple of times.

Problem:
I cannot ping between the two servers that is on the same subnet.
There is no problem resolving dns-entries to the other server or to
the world but no way to connect to it.

The computers are almost identically configured. What could be a hint
is that if I use the "correct" subnet mask 255.255.255.192 I can ping
the other computer, BUT NOT the world. If I broaden the subnet mask to
255.255.255.0 then I can ping the world BUT NOT the subnet. SO I am
using the x.x.x.0 subnet right now.

So, if I change the subnet and restart the interface, I would likely
have to go myself to the servers and I could do that a couple of times
of course, but now I am turning to you instead to see if there is
something obviuos missing here.

Lead: During installation, no firewall was set and the router is still
outside the fw during this period.

There are two adapters on both machines, but only eth0 is connected to
any network.

If you could help out here, I would be bery grateful.

regards, Axier

Following data is identical on both machines:
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref
Use Iface
xxx.yyy.80.0 0.0.0.0 255.255.255.0 U 0 0
0 eth1
xxx.yyy.80.0 0.0.0.0 255.255.255.0 U 0 0
0 eth1
169.254.0.0 0.0.0.0 255.255.0.0 U 0 0
0 eth1
127.0.0.0 0.0.0.0 255.0.0.0 U 0 0
0 lo
0.0.0.0 xxx.yyy.80.193 0.0.0.0 UG 0 0
0 eth0

etc/hosts:
127.0.0.1 mail.mysite.org mail localhost.localdomain
localhost
xxx.yyy.80.233 corp.mysite.org
xxx.yyy.80.234 mail.mysite.org

Machine corp:
ifconfig eth0,
eth0 Link encap:Ethernet HWaddr 00:0A:E4:00:68:FD
inet addr:xxx.yyy.80.233 Bcast:xxx.yyy.80.255
Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:886946 errors:0 dropped:0 overruns:0 frame:0
TX packets:308601 errors:0 dropped:0 overruns:0 carrier:0
collisions:9957 txqueuelen:100
RX bytes:161204850 (153.7 Mb) TX bytes:57625475 (54.9 Mb)
Interrupt:10 Base address:0x4000 Memory:fcde0000-fce00000

DEVICE=eth0
ONBOOT=yes
BOOTPROTO=static
IPADDR=xxx.yyy.80.233
NETMASK=255.255.255.0
GATEWAY=xxx.yyy.80.193
BROADCAST=xxx.yyy.80.255
NETWORK=xxx.yyy.80.0

Machine mail:
ifconfig eth0
eth0 Link encap:Ethernet HWaddr 00:02:B3:86:17:66
inet addr:xxx.yyy.80.234 Bcast:xxx.yyy.80.255
Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:696219 errors:0 dropped:0 overruns:0 frame:0
TX packets:132847 errors:6 dropped:0 overruns:0 carrier:6
collisions:5971 txqueuelen:100
RX bytes:44489300 (42.4 Mb) TX bytes:41717166 (39.7 Mb)
Interrupt:5 Base address:0xef00 Memory:febfb000-febfb038

/etc/sysconfig/network-scripts/ifcfg-eth0
DEVICE=eth0
ONBOOT=yes
BOOTPROTO=static
IPADDR=xxx.yyy.80.234
NETMASK=255.255.255.0
GATEWAY=xxx.yyy.80.193
BROADCAST=xxx.yyy.80.255
NETWORK=xxx.yyy.80.0
 
Reply With Quote
 
 
 
 
David Efflandt
Guest
Posts: n/a

 
      09-08-2003, 07:45 AM
On 7 Sep 2003 01:58:57 -0700, Axier <(E-Mail Removed)> wrote:
> Guys,
>
> I am trying to figure this out. It is a little problematic for me to
> experiment too much with the network adapters since I am sitting
> remote and
> have already driven down to the servers to console into them to
> correct a few mistakes a couple of times.
>
> Problem:
> I cannot ping between the two servers that is on the same subnet.
> There is no problem resolving dns-entries to the other server or to
> the world but no way to connect to it.
>
> The computers are almost identically configured. What could be a hint
> is that if I use the "correct" subnet mask 255.255.255.192 I can ping
> the other computer, BUT NOT the world. If I broaden the subnet mask to
> 255.255.255.0 then I can ping the world BUT NOT the subnet. SO I am
> using the x.x.x.0 subnet right now.
>
> So, if I change the subnet and restart the interface, I would likely
> have to go myself to the servers and I could do that a couple of times
> of course, but now I am turning to you instead to see if there is
> something obviuos missing here.
>
> Lead: During installation, no firewall was set and the router is still
> outside the fw during this period.
>
> There are two adapters on both machines, but only eth0 is connected to
> any network.
>
> If you could help out here, I would be bery grateful.
>
> regards, Axier
>
> Following data is identical on both machines:
> Kernel IP routing table
> Destination Gateway Genmask Flags Metric Ref
> Use Iface
> xxx.yyy.80.0 0.0.0.0 255.255.255.0 U 0 0
> 0 eth1
> xxx.yyy.80.0 0.0.0.0 255.255.255.0 U 0 0
> 0 eth1
> 169.254.0.0 0.0.0.0 255.255.0.0 U 0 0
> 0 eth1
> 127.0.0.0 0.0.0.0 255.0.0.0 U 0 0
> 0 lo
> 0.0.0.0 xxx.yyy.80.193 0.0.0.0 UG 0 0
> 0 eth0


Something is fishy with above routing. You have a duplicate network route
on (supposedly unused) eth1 and a default route that should not be
possible, because there is no route to that IP or network on eth0. Why
does eth1 even show up at all if it is disabled (or is it?)? Maybe you
need to add the following to /etc/modules.conf:

alias eth1 off

> etc/hosts:
> 127.0.0.1 mail.mysite.org mail localhost.localdomain
> localhost
> xxx.yyy.80.233 corp.mysite.org
> xxx.yyy.80.234 mail.mysite.org


It is best not to tamper with 127.0.0.1 line. Should be:

127.0.0.1 localhost.localdomain localhost
xxx.yyy.80.233 corp.mysite.org corp
xxx.yyy.80.234 mail.mysite.org mail

> Machine corp:
> ifconfig eth0,
> eth0 Link encap:Ethernet HWaddr 00:0A:E4:00:68:FD
> inet addr:xxx.yyy.80.233 Bcast:xxx.yyy.80.255
> Mask:255.255.255.0
> UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
> RX packets:886946 errors:0 dropped:0 overruns:0 frame:0
> TX packets:308601 errors:0 dropped:0 overruns:0 carrier:0
> collisions:9957 txqueuelen:100
> RX bytes:161204850 (153.7 Mb) TX bytes:57625475 (54.9 Mb)
> Interrupt:10 Base address:0x4000 Memory:fcde0000-fce00000
>
> DEVICE=eth0
> ONBOOT=yes
> BOOTPROTO=static
> IPADDR=xxx.yyy.80.233
> NETMASK=255.255.255.0
> GATEWAY=xxx.yyy.80.193
> BROADCAST=xxx.yyy.80.255
> NETWORK=xxx.yyy.80.0


You say your netmask should be 255.255.255.192, have you tried (maybe
NETWORK was incorrect):

DEVICE=eth0
ONBOOT=yes
BOOTPROTO=static
IPADDR=xxx.yyy.80.233
NETMASK=255.255.255.192
GATEWAY=xxx.yyy.80.193
BROADCAST=xxx.yyy.80.255
NETWORK=xxx.yyy.80.192

But that assumes that the device at xxx.yyy.80.193 is properly configured.
What kind of device is the gateway (what is its routing) and what ties
that to these 2 boxes (switch ports, separate switch?)?

> Machine mail:
> ifconfig eth0
> eth0 Link encap:Ethernet HWaddr 00:02:B3:86:17:66
> inet addr:xxx.yyy.80.234 Bcast:xxx.yyy.80.255
> Mask:255.255.255.0
> UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
> RX packets:696219 errors:0 dropped:0 overruns:0 frame:0
> TX packets:132847 errors:6 dropped:0 overruns:0 carrier:6
> collisions:5971 txqueuelen:100
> RX bytes:44489300 (42.4 Mb) TX bytes:41717166 (39.7 Mb)
> Interrupt:5 Base address:0xef00 Memory:febfb000-febfb038
>
> /etc/sysconfig/network-scripts/ifcfg-eth0
> DEVICE=eth0
> ONBOOT=yes
> BOOTPROTO=static
> IPADDR=xxx.yyy.80.234
> NETMASK=255.255.255.0
> GATEWAY=xxx.yyy.80.193
> BROADCAST=xxx.yyy.80.255
> NETWORK=xxx.yyy.80.0



--
David Efflandt - All spam ignored http://www.de-srv.com/
http://www.autox.chicago.il.us/ http://www.berniesfloral.net/
http://cgi-help.virtualave.net/ http://hammer.prohosting.com/~cgi-wiz/
 
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Cannot ping two computers on same subnet =?Utf-8?B?TVNN?= Broadband Hardware 5 12-20-2005 04:08 AM
Unable to ping linux server from different subnet. Paul Graves Linux Networking 1 07-20-2003 02:28 PM
Cannot ping linux from different subnet. Paul Graves Linux Networking 0 07-19-2003 07:24 PM
Re: Cannot ping host in another subnet M. Swope Linux Networking 1 06-24-2003 10:34 PM
Re: Cannot ping host in another subnet Michael Heiming Linux Networking 1 06-24-2003 06:36 PM



1 2 3 4 5 6 7 8 9 10 11