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Old 05-17-2012, 08:51 PM
Sanjay Arora
 
Default Centos 6 - Networking: Some Queries

Hello all

I am setting up a Centos 6 machine with one network card & one onboard
network port. Both are recognized & work. Onboard Network port is unused
yet, but is required for dedicated access to LTSP LAN, which would allow
older PIII machines to boot from this system. I have installed LTSP but
again Networking seems to be the problem area, as the clients won't boot
from this machine.

Have muddled & tinkered with Networking a bit...deleted & reconfigured the
ifcfg files again & again but as I don't understand NetworkManager and
Google is not helping get relevant results, so I have brought the system to
minimum working condition, where one network card is providing LAN access
on which Internet Router is configured. And now I am posting my system's
condition below as output of various commands.

My network-scripts directory:

[root@swyam network-scripts]# ls
ifcfg-Internet_GW ifup-eth
ifcfg-lo ifup-ippp
ifdown ifup-ipv6
ifdown-bnep ifup-isdn
ifdown-eth ifup-plip
ifdown-ippp ifup-plusb
ifdown-ipv6 ifup-post
ifdown-isdn ifup-ppp
ifdown-post ifup-routes
ifdown-ppp ifup-sit
ifdown-routes ifup-tunnel
ifdown-sit ifup-wireless
ifdown-tunnel init.ipv6-global
ifup net.hotplug
ifup-aliases network-functions
ifup-bnep network-functions-ipv6

Ifconfig output:

[root@swyam network-scripts]# ifconfig
eth0 Link encap:Ethernet HWaddr E0:69:95:77:A7:F3
UP BROADCAST MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)
Interrupt:20 Memory:fe600000-fe620000

eth1 Link encap:Ethernet HWaddr 00:60:52:0C:0BE
inet addr:192.168.1.3 Bcast:192.168.1.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:2245698 errors:0 dropped:0 overruns:0 frame:0
TX packets:1785431 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:3105161344 (2.8 GiB) TX bytes:148843277 (141.9 MiB)
Interrupt:16 Base address:0x2000

lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:525 errors:0 dropped:0 overruns:0 frame:0
TX packets:525 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:53459 (52.2 KiB) TX bytes:53459 (52.2 KiB)

[root@swyam network-scripts]# cat ifcfg-Internet_GW
TYPE=Ethernet
BOOTPROTO=none
IPADDR=192.168.1.3
PREFIX=24
GATEWAY=192.168.1.1
DNS1=218.248.245.1
DNS2=8.8.8.8
DOMAIN="218.248.245.1 8.8.8.8 8.8.4.4"
DEFROUTE=yes
IPV4_FAILURE_FATAL=yes
IPV6INIT=no
NAME="Internet GW"
UUID=d4535709-a05b-459d-a4fd-f08ec9460bcc
ONBOOT=yes
DNS3=8.8.4.4

Network Manager is running and the above card "Internet_GW" was configured
through the NetworkManager applet. Internet works. One can disconnect
Internet through the NetworkManager applet. Yet the applet's Edit
Connection --> Wired --> Last Used status shows "Never".

Now let's come to what I want to do with this machine....The Onboard
network port for LTSP services....Network card on network
192.168.1.0/24(192.168.1.1 is the ISP ADSL router) to provide LAN
access & Internet
access.

Now what I want to do is to create a third network for my virtual machines
(KVM) say 172.16.1.1/24. Now create some sort of dummy bridge and get these
machines talking to the Internet....said bridge to either forward the
packets through the normal Internet path or somehow use NAT to do it. I
think this should be doable but haven't come across any example or any
tutorial for this.

Now comes why I want a separate network....why not use
192.168.1.0/24...problem is...I don't want to disable Network Manager by
putting Managed=NO in my ifcfg file. As with Network Manager enabled, I can
use USB devices whenever my ISP goes down....and I'm afraid it happens more
frequently than I care to bear.

I frankly also don't understand how Network Manager works....in a broad
manner....literature I found was either too technical or too old or was
focussed on a particular problem.

I would like to know a network/bridge/device topology that can solve my
issue....three networks...lan. ltsp, virtual machines, all having access to
each other & the net, while keeping the option of using networkmanager or
any other tool (I'm open) to plugin any other wireless internet access
device.

I am not very advanced admin, but can follow instructions.

Kindly help.

With regards & thanks.
Sanjay.
_______________________________________________
CentOS mailing list
CentOS@centos.org
http://lists.centos.org/mailman/listinfo/centos
 
Old 05-21-2012, 10:17 AM
Ljubomir Ljubojevic
 
Default Centos 6 - Networking: Some Queries

On 05/17/2012 10:51 PM, Sanjay Arora wrote:
> Hello all
>
> I am setting up a Centos 6 machine with one network card& one onboard
> network port. Both are recognized& work. Onboard Network port is unused
> yet, but is required for dedicated access to LTSP LAN, which would allow
> older PIII machines to boot from this system. I have installed LTSP but
> again Networking seems to be the problem area, as the clients won't boot
> from this machine.
>
> Have muddled& tinkered with Networking a bit...deleted& reconfigured the
> ifcfg files again& again but as I don't understand NetworkManager and
> Google is not helping get relevant results, so I have brought the system to
> minimum working condition, where one network card is providing LAN access
> on which Internet Router is configured. And now I am posting my system's
> condition below as output of various commands.
>
> My network-scripts directory:
>
> [root@swyam network-scripts]# ls
> ifcfg-Internet_GW ifup-eth
> ifcfg-lo ifup-ippp
> ifdown ifup-ipv6
> ifdown-bnep ifup-isdn
> ifdown-eth ifup-plip
> ifdown-ippp ifup-plusb
> ifdown-ipv6 ifup-post
> ifdown-isdn ifup-ppp
> ifdown-post ifup-routes
> ifdown-ppp ifup-sit
> ifdown-routes ifup-tunnel
> ifdown-sit ifup-wireless
> ifdown-tunnel init.ipv6-global
> ifup net.hotplug
> ifup-aliases network-functions
> ifup-bnep network-functions-ipv6
>
> Ifconfig output:
>
> [root@swyam network-scripts]# ifconfig
> eth0 Link encap:Ethernet HWaddr E0:69:95:77:A7:F3
> UP BROADCAST MULTICAST MTU:1500 Metric:1
> RX packets:0 errors:0 dropped:0 overruns:0 frame:0
> TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
> collisions:0 txqueuelen:1000
> RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)
> Interrupt:20 Memory:fe600000-fe620000
>
> eth1 Link encap:Ethernet HWaddr 00:60:52:0C:0BE
> inet addr:192.168.1.3 Bcast:192.168.1.255 Mask:255.255.255.0
> UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
> RX packets:2245698 errors:0 dropped:0 overruns:0 frame:0
> TX packets:1785431 errors:0 dropped:0 overruns:0 carrier:0
> collisions:0 txqueuelen:1000
> RX bytes:3105161344 (2.8 GiB) TX bytes:148843277 (141.9 MiB)
> Interrupt:16 Base address:0x2000
>
> lo Link encap:Local Loopback
> inet addr:127.0.0.1 Mask:255.0.0.0
> UP LOOPBACK RUNNING MTU:16436 Metric:1
> RX packets:525 errors:0 dropped:0 overruns:0 frame:0
> TX packets:525 errors:0 dropped:0 overruns:0 carrier:0
> collisions:0 txqueuelen:0
> RX bytes:53459 (52.2 KiB) TX bytes:53459 (52.2 KiB)
>
> [root@swyam network-scripts]# cat ifcfg-Internet_GW
> TYPE=Ethernet
> BOOTPROTO=none
> IPADDR=192.168.1.3
> PREFIX=24
> GATEWAY=192.168.1.1
> DNS1=218.248.245.1
> DNS2=8.8.8.8
> DOMAIN="218.248.245.1 8.8.8.8 8.8.4.4"
> DEFROUTE=yes
> IPV4_FAILURE_FATAL=yes
> IPV6INIT=no
> NAME="Internet GW"
> UUID=d4535709-a05b-459d-a4fd-f08ec9460bcc
> ONBOOT=yes
> DNS3=8.8.4.4
>
> Network Manager is running and the above card "Internet_GW" was configured
> through the NetworkManager applet. Internet works. One can disconnect
> Internet through the NetworkManager applet. Yet the applet's Edit
> Connection --> Wired --> Last Used status shows "Never".
>
> Now let's come to what I want to do with this machine....The Onboard
> network port for LTSP services....Network card on network
> 192.168.1.0/24(192.168.1.1 is the ISP ADSL router) to provide LAN
> access& Internet
> access.
>
> Now what I want to do is to create a third network for my virtual machines
> (KVM) say 172.16.1.1/24. Now create some sort of dummy bridge and get these
> machines talking to the Internet....said bridge to either forward the
> packets through the normal Internet path or somehow use NAT to do it. I
> think this should be doable but haven't come across any example or any
> tutorial for this.
>
> Now comes why I want a separate network....why not use
> 192.168.1.0/24...problem is...I don't want to disable Network Manager by
> putting Managed=NO in my ifcfg file. As with Network Manager enabled, I can
> use USB devices whenever my ISP goes down....and I'm afraid it happens more
> frequently than I care to bear.
>
> I frankly also don't understand how Network Manager works....in a broad
> manner....literature I found was either too technical or too old or was
> focussed on a particular problem.
>
> I would like to know a network/bridge/device topology that can solve my
> issue....three networks...lan. ltsp, virtual machines, all having access to
> each other& the net, while keeping the option of using networkmanager or
> any other tool (I'm open) to plugin any other wireless internet access
> device.
>
> I am not very advanced admin, but can follow instructions.
>
> Kindly help.
>

NetworkManager does not (as far as I know) use ifcfg files unless you
select "Available for all users" checkbox, but rather keeps interface
data somewhere inside $HOME directory (.gconf subdirectory maybe) in
unreadable format for humans.

"Available for all users" will help you, or run "network" service and
disable "NetworkManager" service.

--

Ljubomir Ljubojevic
(Love is in the Air)
PL Computers
Serbia, Europe

Google is the Mother, Google is the Father, and traceroute is your
trusty Spiderman...
StarOS, Mikrotik and CentOS/RHEL/Linux consultant
_______________________________________________
CentOS mailing list
CentOS@centos.org
http://lists.centos.org/mailman/listinfo/centos
 
Old 05-21-2012, 01:26 PM
Timothy Murphy
 
Default Centos 6 - Networking: Some Queries

Ljubomir Ljubojevic wrote:

> NetworkManager does not (as far as I know) use ifcfg files unless you
> select "Available for all users" checkbox, but rather keeps interface
> data somewhere inside $HOME directory (.gconf subdirectory maybe) in
> unreadable format for humans.

Is this true?
I have the impression that NM takes note of NM_MANAGED=yes or no
in /etc/sysconfig/network-scripts/ifcfg-wlan0 (or whatever).
So I assume from this that NM must read these files.

I wish someone would document NM,
explaining what files it consults,
and something about how it is supposed to function.

In my experience NM works fine 95% of the time;
but when it does not work it is often very difficult
to work out exactly where the problem lies.
In particular the entries in /var/log/messages
are completely useless.

Another annoyance is that the network service
seems to have got tangled up with NM, at least in Fedora-16;
they used to be more or less independent.

--
Timothy Murphy
e-mail: gayleard /at/ eircom.net
tel: +353-86-2336090, +353-1-2842366
s-mail: School of Mathematics, Trinity College Dublin


_______________________________________________
CentOS mailing list
CentOS@centos.org
http://lists.centos.org/mailman/listinfo/centos
 
Old 05-23-2012, 12:04 AM
Ljubomir Ljubojevic
 
Default Centos 6 - Networking: Some Queries

On 05/21/2012 03:26 PM, Timothy Murphy wrote:
> Ljubomir Ljubojevic wrote:
>
>> NetworkManager does not (as far as I know) use ifcfg files unless you
>> select "Available for all users" checkbox, but rather keeps interface
>> data somewhere inside $HOME directory (.gconf subdirectory maybe) in
>> unreadable format for humans.
>
> Is this true?
> I have the impression that NM takes note of NM_MANAGED=yes or no
> in /etc/sysconfig/network-scripts/ifcfg-wlan0 (or whatever).
> So I assume from this that NM must read these files.

Somewhere on the net, undefined time ago (last 2-3 months?) I was asked
same question and I investigated on my laptop that has NetworkManager
service enabled. But I can not remember when/where I posted results. I
think it was in "Linux" Facebook group but search gives nothing.

Do not take my word for it, create NM connection and observe what is
happening. And I will run my laptop tomorrow and see if I wrote the
search results somewhere.

--

Ljubomir Ljubojevic
(Love is in the Air)
PL Computers
Serbia, Europe

Google is the Mother, Google is the Father, and traceroute is your
trusty Spiderman...
StarOS, Mikrotik and CentOS/RHEL/Linux consultant
_______________________________________________
CentOS mailing list
CentOS@centos.org
http://lists.centos.org/mailman/listinfo/centos
 

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