Re: [CentOS] Need help getting two NICs to work on CentOS 7

[Gordon Messmer]

On 11/16/2016 07:33 AM, Sean Son wrote:

No matter how many times I
restart the NetworkManager-dispatcher service, if I reboot the system, and
run a systemctl status NetworkManager-dispatcher.service, the service shows
as Inactive (Dead) even though it has been enabled.


That's normal.  It's a dbus-invoked service.  You don't need to manually 
enable it.  It runs a command when it's invoked, and then terminates.  
There isn't a daemon process associated with the service.



Also whenever I
reboot the VM, after logging into the GUI, I get a pop up that says failed
to activate network connection , yet I still have network connectivity.
Any ideas on what I can do to fix these things?


Not really.  The log might tell you why it thinks an interface wasn't 
successfully enabled.



   Also overall, because I am
using a static IP config for both NICs, is it better to just disable
NetworkManager and use network scripts instead?


Not generally.  If you find the old network service works better for 
your use case, it's available.  I use it on a small number of hosts 
where NM bugs interfere with normal operation, but I'm waiting for the 
7.3 updates (where NM has been rebased to a newer version) to see if I 
can stop doing that.

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Re: [CentOS] Need help getting two NICs to work on CentOS 7

[Sean Son]

On Tue, Nov 15, 2016 at 10:55 AM, Gordon Messmer 
wrote:

> On 11/15/2016 06:07 AM, Sean Son wrote:
>
>> I have no network connectivity even
>> when I restart the network service.  Should I reenable NetworkManager now?
>>
>
>
> Yeah, the switch is just a test to see if the problem is specific to
> NetworkManager.  It seems that you have other problems as well.
>
> Before you do that, post the output of the following:
>
> ip route show
>
> ip route show table 300
>
> ip route show table 301
>
> ip rule show
>
> cat /etc/sysconfig/network-scripts/ifcfg-eth0
>
> cat /etc/sysconfig/network-scripts/route-eth0
>
> cat /etc/sysconfig/network-scripts/rule-eth0
>
> cat /etc/sysconfig/network-scripts/ifcfg-eth1
>
> cat /etc/sysconfig/network-scripts/route-eth1
>
> cat /etc/sysconfig/network-scripts/rule-eth1
>
>
>
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Hello

I think i figured it out.   I had forgotten to install
NetworkManager-config-routing-rules and then enable and start the
NetworkManager-dispatcher service.   I tried that on a different test
machine and I am able to ping both of the IPs from another machine just
fine. Only a few things I have noticed:   No matter how many times I
restart the NetworkManager-dispatcher service, if I reboot the system, and
run a systemctl status NetworkManager-dispatcher.service, the service shows
as Inactive (Dead) even though it has been enabled.   Also whenever I
reboot the VM, after logging into the GUI, I get a pop up that says failed
to activate network connection , yet I still have network connectivity.
Any ideas on what I can do to fix these things?  Also overall, because I am
using a static IP config for both NICs, is it better to just disable
NetworkManager and use network scripts instead?



Thanks!!
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Re: [CentOS] Need help getting two NICs to work on CentOS 7

[Gordon Messmer]

On 11/15/2016 06:07 AM, Sean Son wrote:

I have no network connectivity even
when I restart the network service.  Should I reenable NetworkManager now?



Yeah, the switch is just a test to see if the problem is specific to 
NetworkManager.  It seems that you have other problems as well.


Before you do that, post the output of the following:

ip route show

ip route show table 300

ip route show table 301

ip rule show

cat /etc/sysconfig/network-scripts/ifcfg-eth0

cat /etc/sysconfig/network-scripts/route-eth0

cat /etc/sysconfig/network-scripts/rule-eth0

cat /etc/sysconfig/network-scripts/ifcfg-eth1

cat /etc/sysconfig/network-scripts/route-eth1

cat /etc/sysconfig/network-scripts/rule-eth1


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Re: [CentOS] Need help getting two NICs to work on CentOS 7

[Sean Son]

On Mon, Nov 14, 2016 at 5:30 PM, Gordon Messmer 
wrote:

> On 11/14/2016 12:47 PM, Sean Son wrote:
>
>> Any ideas on what
>> I am doing wrong here?
>>
>
>
> Nothing obvious.  Since your interfaces have static configurations, I'd
> suggest turning off NetworkManager and turning on the "network" service to
> determine whether or not that works correctly after a reboot.
>
> Assuming it does, fixing the issue might be as simple as getting
> NetworkManager to not rename one interface to "wired connection 1".
>
>
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Hello Gordon

Thank you for your response.  I disabled NetworkManager and started the
network service, then I rebooted the VM and now 'ip rule show' has the
rules for both interfaces showing but I have no network connectivity even
when I restart the network service.  Should I reenable NetworkManager now?
How would I go about getting NetworkManager to stop creating new Interface
files and naming them Wired_connection-*?


Thanks!
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Re: [CentOS] Need help getting two NICs to work on CentOS 7

[Gordon Messmer]

On 11/14/2016 12:47 PM, Sean Son wrote:

Any ideas on what
I am doing wrong here?



Nothing obvious.  Since your interfaces have static configurations, I'd 
suggest turning off NetworkManager and turning on the "network" service 
to determine whether or not that works correctly after a reboot.


Assuming it does, fixing the issue might be as simple as getting 
NetworkManager to not rename one interface to "wired connection 1".


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Re: [CentOS] Need help getting two NICs to work on CentOS 7

[Sean Son]

On Tue, Nov 8, 2016 at 8:02 AM, Boris Epstein  wrote:

> Hello there,
>
> What is the hypervisor that hosts the VM? What does ifconfig show on it?
>
> Boris.
>
> On Mon, Nov 7, 2016 at 4:36 PM, Gordon Messmer 
> wrote:
>
> > On 11/06/2016 11:00 PM, Sean Son wrote:
> >
> >> How do I
> >> configure the networking so that both IPs are pingable and the VM is
> >> reachable via both IPs?
> >>
> >
> >
> > You need one rule file per interface, which directs traffic out the
> > appropriate interface based on the source address of the packet:
> >
> > https://blogs.oracle.com/networking/entry/advance_
> routing_for_multi_homed
> >
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Hello all

Thank you for the replies.  I ran into  some issues with the policy based
routing which I will explain in a few.  First off to answer each one of
your questions:

Digimer: No I didnt take a look at IPTables

Peter Brady: Thank you for the example, I tried that but it failed and I
will explain in a minute.

Frank Cox : That works but how do I make it persistent across reboots?

Boris Epstein:  I am using Hyper-V and its getting annoying lol


Ok so here is how I have set everything up:

my /etc/iproute2/rt_tables:


#
# reserved values
#
255 local
254 main
253 default
0   unspec
#
# local
#
#1  inr.ruhep
300 NIC1
310 NIC2

my /etc/sysconfig/network-scripts/route-eth0 file:

168.87.147.0/24 dev eth0 table 300
default via 168.87.147.1 dev eth0 table 300

/etc/sysconfig/network-scripts/route-eth1 file:

10.20.50.0/24 dev eth1 table 310
default via 10.20.50.1 dev eth1 table 310

My /etc/sysconfig/network-scripts/rule-eth0:

from 168.87.147.33/32 table 300
to 168.87.147.33 table 300

My /etc/sysconfig/network-scripts/rule-eth1:

from 10.20.50.90/32 table 310
to 10.20.50.90 table 310


now after implementing this and restarting NetworkManager,  when I run 'ip
rule list', I get the following:

0:  from all lookup local
32764:  from all to 10.20.50.90 lookup NIC2
32765:  from 10.20.50.90 lookup NIC2
32766:  from all lookup main
32767:  from all lookup default


and when i run 'ip route' , i get the following:

default via 168.87.147.1 dev eth0  proto static  metric 1024
10.20.50.0/24 dev eth1  proto kernel  scope link  src 10.20.50.90
168.87.147.0/24 dev eth0  proto kernel  scope link  src 168.87.147.33



yet when I try to ping from another server to 10.20.50.90 it will not ping
at all. Also, whenever I reboot the VM, eth1 switches over to DHCP and I
lose my IP configuration. After I reset the IP Configuration back to Manual
and reenter the IP, Centos creates a new interface file called
ifcfg-Wired_Connection-1 and places the IP configuration for the interface
into that file. Both virtual NICs are set to Static Mac Addresses, so I
dont know why it keeps creating another interface file.  Any ideas on what
I am doing wrong here? All help is greatly appreciated!


Thanks!
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Re: [CentOS] Need help getting two NICs to work on CentOS 7

[Boris Epstein]

Hello there,

What is the hypervisor that hosts the VM? What does ifconfig show on it?

Boris.

On Mon, Nov 7, 2016 at 4:36 PM, Gordon Messmer 
wrote:

> On 11/06/2016 11:00 PM, Sean Son wrote:
>
>> How do I
>> configure the networking so that both IPs are pingable and the VM is
>> reachable via both IPs?
>>
>
>
> You need one rule file per interface, which directs traffic out the
> appropriate interface based on the source address of the packet:
>
> https://blogs.oracle.com/networking/entry/advance_routing_for_multi_homed
>
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Re: [CentOS] Need help getting two NICs to work on CentOS 7

[lejeczek]

On 07/11/16 07:00, Sean Son wrote:

Hello all

Here is the scenario:  We have a mail server VM which currently has two
virtual NICs attached to it. One NIC is has an IP on a subnet with a
default gateway defined and the other NIC has an IP on a different subnet
with a different gateway on a different VLAN defined. Now when I activate
both NICs, and run an ifconfig -a, I see that both IP addresses are
showing. Now here is the problem. When I ping the VM, the first NIC's IP is
not pingable at all, but the second NIC's IP is pingable. How do I
configure the networking so that both IPs are pingable and the VM is
reachable via both IPs? Please let me know what I may be doing wrong!


Thank you!

Sean
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policy based routing is useful concept but in my mind should 
be the very last resort.
It is the kernel's networking functions which are 
responsible for routing tables construction and if you can 
shed more details (like mentioned earlier) on what can(not) 
ping what(VM hosting box <-> VM guest / outside internal net 
<-> VM / etc.) centbuddies could share more concrete 
thoughts then.
Basically - with policy/source based routing you need to be 
very careful, test everything - best is to leave it to the 
kernel and only use main table, kernel should be the 
smartest, for more complex setups maybe think "routing daemons".

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Re: [CentOS] Need help getting two NICs to work on CentOS 7

[Gordon Messmer]

On 11/06/2016 11:00 PM, Sean Son wrote:

How do I
configure the networking so that both IPs are pingable and the VM is
reachable via both IPs?



You need one rule file per interface, which directs traffic out the 
appropriate interface based on the source address of the packet:


https://blogs.oracle.com/networking/entry/advance_routing_for_multi_homed

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Re: [CentOS] Need help getting two NICs to work on CentOS 7

[Peter Brady]

On 7/11/2016 6:00 PM, Sean Son wrote:
> Hello all
>
> Here is the scenario:  We have a mail server VM which currently has two
> virtual NICs attached to it. One NIC is has an IP on a subnet with a
> default gateway defined and the other NIC has an IP on a different subnet
> with a different gateway on a different VLAN defined. Now when I activate
> both NICs, and run an ifconfig -a, I see that both IP addresses are
> showing. Now here is the problem. When I ping the VM, the first NIC's IP is
> not pingable at all, but the second NIC's IP is pingable. How do I
> configure the networking so that both IPs are pingable and the VM is
> reachable via both IPs? Please let me know what I may be doing wrong!
>
I've done this recently on C7.  The key words for your Google Fu is
policy based routing.  That ensures the incoming packets come back out
the same interface they came in on.  Mind you, depending on the routers
in the way this may not be a problem.  CISCO ASAs get really picky but
otherwise there may be other problems to deal with as well.

If you're using Network Manager then the package:
NetworkManager-config-routing-rules will help.

After that you create the rules and routes files in
/etc/sysconfig/network-scripts

So in my case I have:

  * enp3s0: 192.168.20.253 (the default gateway on this subnet is
192.168.20.2)
  * vlan22@enp3s0: 192.168.22.253 (the default gateway on this subnet is
192.168.22.1)

[root@host network-scripts]# cat route-enp3s0
192.168.20.0/24 dev enp3s0 tab 20
default via 192.168.20.2 dev enp3s0 tab 20

[root@host network-scripts]# cat rule-enp3s0
from 192.168.20.0/24 tab 20 priority 20

[root@host network-scripts]# cat route-vlan22
192.168.22.0/24 dev vlan22 tab 22
default via 192.168.22.1 dev vlan22 tab 22

[root@host network-scripts]# cat rule-vlan22
from 192.168.22.0/24 tab 22 priority 22

Wireshark can be really helpful here as it can confirm that the
"unpingable" NIC is actually receiving the packets that you think it
is.  And hopefully in that case can also confirm if the echo packets are
going out the alternate NIC.  If there are no incoming packets then the
PBR is no real help at all and you'd need to look further upstream.

Hope that helps,
-pete




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Re: [CentOS] Need help getting two NICs to work on CentOS 7

[Frank Cox]

On Mon, 7 Nov 2016 02:00:24 -0500
Sean Son wrote:

>  When I ping the VM, the first NIC's IP is
> not pingable at all, but the second NIC's IP is pingable. How do I
> configure the networking so that both IPs are pingable and the VM is
> reachable via both IPs? 

The last time I did that I did it on Centos 5.  Here are my notes from back 
then.

First, add two lines to /etc/iproute2/rt_tables, so it looks like this:

#
# reserved values
#
255 local
254 main
253 default
0   unspec
#
# local
#
#1  inr.ruhep
50  access1
60  access2

Then add the following routes:

ip route add 1.2.3.0/24 dev eth1 table access1
ip route add default via 1.2.3.1 dev eth1 table access1
ip rule add from 1.2.3.178/32 lookup access1

ip route add 1.2.3.0/24 dev eth2 table access2
ip route add default via 1.2.3.1 dev eth2 table access2
ip rule add from 1.2.3.180/32 lookup access2

Of course, in this example 1.2.3.178 is the IP address of the first nic and 
1.2.3.180 is the address of the second nic.


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Re: [CentOS] Need help getting two NICs to work on CentOS 7

[Digimer]

On 07/11/16 02:00 AM, Sean Son wrote:
> Hello all
> 
> Here is the scenario:  We have a mail server VM which currently has two
> virtual NICs attached to it. One NIC is has an IP on a subnet with a
> default gateway defined and the other NIC has an IP on a different subnet
> with a different gateway on a different VLAN defined. Now when I activate
> both NICs, and run an ifconfig -a, I see that both IP addresses are
> showing. Now here is the problem. When I ping the VM, the first NIC's IP is
> not pingable at all, but the second NIC's IP is pingable. How do I
> configure the networking so that both IPs are pingable and the VM is
> reachable via both IPs? Please let me know what I may be doing wrong!

We're missing a lot of details, but to speak generally, I'd look at the
bridging on the host if you're confident that the interfaces are
configured properly inside the host.

Also, have you looked at iptables?

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[CentOS] Need help getting two NICs to work on CentOS 7

[Sean Son]

Hello all

Here is the scenario:  We have a mail server VM which currently has two
virtual NICs attached to it. One NIC is has an IP on a subnet with a
default gateway defined and the other NIC has an IP on a different subnet
with a different gateway on a different VLAN defined. Now when I activate
both NICs, and run an ifconfig -a, I see that both IP addresses are
showing. Now here is the problem. When I ping the VM, the first NIC's IP is
not pingable at all, but the second NIC's IP is pingable. How do I
configure the networking so that both IPs are pingable and the VM is
reachable via both IPs? Please let me know what I may be doing wrong!


Thank you!

Sean
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