Re: [CentOS] Gateway question

[Levente Birta]

On 10/08/2016 16:54, Anthony K wrote:

On 10/08/16 16:29, Levente Birta wrote:

And as I said this problem is resolved too ... I asked for another way
to achieve this

When you add a default gateway with:

route add default gw 192.168.1.1 dev enp3s0

you'll note that you now have 2 routes with the same metric of 0 (use
route -n to see the metric field - couldn't get ip route to show me the
metric).

When using ip route command, you need to specify a different metric
otherwise it won't take.  To me, ip route is doing the right thing as
having 2 gateways with the same metric will confuse the routing process.

If you need to use ip route to add another default gateway, make sure to
use a different metric:

ip route add 0/0 via 192.168.1.1 dev enp3s0 metric


ak.



PS: In my virtual environment *[0]*, the routing tables for tables t2
and t3 appeared incomplete.  The route specified in the route files for
network 192.168.1.0/24 was missing - most likely cause it was already in
the main routing table.  Only the default route appeared in the tables

$ cat /etc/sysconfig/network-scripts/route-enp0s3
192.168.1.0/24 dev enp0s3 src 192.168.1.12 table t2
default via 192.168.1.1 dev enp0s3 table t2

$ cat /etc/sysconfig/network-scripts/route-enp0s8
192.168.1.0/24 dev enp0s8 src 192.168.1.13 table t3
default via 192.168.1.1 dev enp0s8 table t3

$ ip r l t t2
default via 192.168.1.1 dev enp0s3

$ ip r l t t3
default via 192.168.1.1 dev enp0s8

*[0]* - https://imagebin.ca/v/2r5NJgNEqSgQ




Yeah ... the metric solved

Just added to route-enp3s0:
0/0 via 192.168.1.1 dev enp3s0 metric 1

Thanks!!

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Re: [CentOS] Gateway question

[Anthony K]

On 10/08/16 16:29, Levente Birta wrote:
And as I said this problem is resolved too ... I asked for another way 
to achieve this

When you add a default gateway with:

route add default gw 192.168.1.1 dev enp3s0

you'll note that you now have 2 routes with the same metric of 0 (use 
route -n to see the metric field - couldn't get ip route to show me the 
metric).


When using ip route command, you need to specify a different metric 
otherwise it won't take.  To me, ip route is doing the right thing as 
having 2 gateways with the same metric will confuse the routing process.


If you need to use ip route to add another default gateway, make sure to 
use a different metric:


ip route add 0/0 via 192.168.1.1 dev enp3s0 metric 



ak.



PS: In my virtual environment *[0]*, the routing tables for tables t2 
and t3 appeared incomplete.  The route specified in the route files for 
network 192.168.1.0/24 was missing - most likely cause it was already in 
the main routing table.  Only the default route appeared in the tables


$ cat /etc/sysconfig/network-scripts/route-enp0s3
192.168.1.0/24 dev enp0s3 src 192.168.1.12 table t2
default via 192.168.1.1 dev enp0s3 table t2

$ cat /etc/sysconfig/network-scripts/route-enp0s8
192.168.1.0/24 dev enp0s8 src 192.168.1.13 table t3
default via 192.168.1.1 dev enp0s8 table t3

$ ip r l t t2
default via 192.168.1.1 dev enp0s3

$ ip r l t t3
default via 192.168.1.1 dev enp0s8

*[0]* - https://imagebin.ca/v/2r5NJgNEqSgQ

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Re: [CentOS] Gateway question

[Levente Birta]

On 10/08/2016 15:28, Jonathan Billings wrote:

On Wed, Aug 10, 2016 at 09:29:15AM +0300, Levente Birta wrote:

I read the document again ... and this talk about accessing this multi-homed
host from the internet...
I have all this configured and working!


You say this is working because of the output here?

# ip route show
default via 192.168.1.1 dev enp3s0
default via 192.168.1.1 dev enp2s0
169.254.0.0/16 dev enp2s0  scope link  metric 1002
169.254.0.0/16 dev enp3s0  scope link  metric 1003
192.168.1.0/24 dev enp2s0  proto kernel  scope link  src 192.168.1.12
192.168.1.0/24 dev enp3s0  proto kernel  scope link  src 192.168.1.13



Yep...

default is:
# ip route show
default via 192.168.1.1 dev enp2s0
169.254.0.0/16 dev enp2s0  scope link  metric 1002
169.254.0.0/16 dev enp3s0  scope link  metric 1003
192.168.1.0/24 dev enp2s0  proto kernel  scope link  src 192.168.1.12
192.168.1.0/24 dev enp3s0  proto kernel  scope link  src 192.168.1.13

and this way not work

Then with the following command:
#route add default gw 192.168.1.1 dev enp3s0

Hurray ... work :)


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Re: [CentOS] Gateway question

[Jonathan Billings]

On Wed, Aug 10, 2016 at 09:29:15AM +0300, Levente Birta wrote:
> I read the document again ... and this talk about accessing this multi-homed
> host from the internet...
> I have all this configured and working!

You say this is working because of the output here?

# ip route show
default via 192.168.1.1 dev enp3s0
default via 192.168.1.1 dev enp2s0
169.254.0.0/16 dev enp2s0  scope link  metric 1002
169.254.0.0/16 dev enp3s0  scope link  metric 1003
192.168.1.0/24 dev enp2s0  proto kernel  scope link  src 192.168.1.12
192.168.1.0/24 dev enp3s0  proto kernel  scope link  src 192.168.1.13

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Re: [CentOS] Gateway question

[Levente Birta]

On 09/08/2016 23:11, Gordon Messmer wrote:

On 08/09/2016 12:03 PM, John R Pierce wrote:

those are both the same network, and the default gateway is a global
thing.  packets forwarded to 192.168.1.1 could use either 192.168.1.12
or .13, as they are all the same.  in reality, they will use the first
match they find.



Generally, but not necessarily.  What Birta is trying to accomplish is
called "multi-homing."   The oracle document I linked to is one of the
shortest, accurate descriptions of its configuration on Red Hat derived
systems that I've come across.


I read the document again ... and this talk about accessing this 
multi-homed host from the internet...

I have all this configured and working!

My problem is when a connection is initiated on this multi-homed or 
whatever host ... and the difference is that in my case the gateway is 
the same for both interfaces


And as I said this problem is resolved too ... I asked for another way 
to achieve this



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Re: [CentOS] Gateway question

[Levente Birta]

On 09/08/2016 23:08, Gordon Messmer wrote:

On 08/09/2016 11:51 AM, Birta Levente wrote:

If I add "#route add default gw 192.168.1.1 dev enp3s0" all is good,
but cannot add that in route-iface file or with "ip route" 



Are you using the "network" or the "NetworkManager" service to configure
your network?  I haven't verified that the route- files are
supported by NetworkManager.

If you are using the older "network" service, then you might be getting
the syntax of the route- file wrong.  If you included the
contents of your ifcfg- and route- files, we could
check.



I'm using older network service ... I hate NetworkManager :)
And all that content was included in the original post, but a copy/paste 
is not a problem:


route-enp2s0:
192.168.1.0/24 dev enp2s0 src 192.168.1.12 table t2
default via 192.168.1.1 dev enp2s0 table t2

route-enp3s0:
192.168.1.0/24 dev enp3s0 src 192.168.1.13 table t3
default via 192.168.1.1 dev enp3s0 table t3

rule-enp2s0:
from 192.168.1.12/32 table t2
to 192.168.1.12/32 table t2

rule-enp3s0:
from 192.168.1.13/32 table t3
to 192.168.1.13/32 table t3



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Re: [CentOS] Gateway question

[Levente Birta]

On 09/08/2016 22:16, John R Pierce wrote:

On 8/9/2016 11:51 AM, Birta Levente wrote:


I do all this and working on LAN ... all traffic go in/out on the
proper interface ... the problem is when I try to access the internet
on the second interface 



how do you try and access the 'internet on the second interface' when
its all the same subnet??   its the same internet, isn't it?




Same internet, yes, but I want through different WAN connection
For example can be postfix binded to different interfaces.
But in this case I want to monitor the two WAN connection with ping. And 
with ping the ICMP packets can be sent on different interfaces.



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Re: [CentOS] Gateway question

[Gordon Messmer]

On 08/09/2016 12:03 PM, John R Pierce wrote:
those are both the same network, and the default gateway is a global 
thing.  packets forwarded to 192.168.1.1 could use either 192.168.1.12 
or .13, as they are all the same.  in reality, they will use the first 
match they find. 



Generally, but not necessarily.  What Birta is trying to accomplish is 
called "multi-homing."   The oracle document I linked to is one of the 
shortest, accurate descriptions of its configuration on Red Hat derived 
systems that I've come across.


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Re: [CentOS] Gateway question

[Gordon Messmer]

On 08/09/2016 11:51 AM, Birta Levente wrote:
If I add "#route add default gw 192.168.1.1 dev enp3s0" all is good, 
but cannot add that in route-iface file or with "ip route"  



Are you using the "network" or the "NetworkManager" service to configure 
your network?  I haven't verified that the route- files are 
supported by NetworkManager.


If you are using the older "network" service, then you might be getting 
the syntax of the route- file wrong.  If you included the 
contents of your ifcfg- and route- files, we could 
check.


Generally, I'm quite certain that the document I provided describes how 
to accomplish specifically what you're trying to accomplish.


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Re: [CentOS] Gateway question

[John R Pierce]

On 8/9/2016 11:51 AM, Birta Levente wrote:


I do all this and working on LAN ... all traffic go in/out on the 
proper interface ... the problem is when I try to access the internet 
on the second interface  



how do you try and access the 'internet on the second interface' when 
its all the same subnet??   its the same internet, isn't it?



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Re: [CentOS] Gateway question

[John R Pierce]

On 8/9/2016 11:42 AM, Birta Levente wrote:

So, again:
Centos 7
2 NICs
enp2s0-192.168.1.12
enp3s0-192.168.1.13
default gateway on enp2s0 is 192.168.1.1, defined in 
/etc/sysconfig/network


Which other way (preferred with "ip route") can I add this, but:
#route add default gw 192.168.1.1 dev enp3s0 


those are both the same network, and the default gateway is a global 
thing.  packets forwarded to 192.168.1.1 could use either 192.168.1.12 
or .13, as they are all the same.  in reality, they will use the first 
match they find.




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Re: [CentOS] Gateway question

[Birta Levente]

On 09/08/2016 20:01, Gordon Messmer wrote:

On 08/08/2016 04:05 AM, Levente Birta wrote:
Can I add this in any config files (ex: route-enp2s0)? 



Yes.  Add a route file for each interface, and set up rules to send 
packets out the corresponding physical interface:


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



Yes, but no :)

I do all this and working on LAN ... all traffic go in/out on the proper 
interface ... the problem is when I try to access the internet on the 
second interface 


If I add "#route add default gw 192.168.1.1 dev enp3s0" all is good, but 
cannot add that in route-iface file or with "ip route" 


Thanks
Levi



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Re: [CentOS] Gateway question

[Birta Levente]

On 09/08/2016 15:47, Jonathan Billings wrote:

On Tue, Aug 09, 2016 at 10:58:40AM +0300, Levente Birta wrote:

What I don't understand why the route command allow to add a second default
gateway with different interface, but the ip route command doesn't?

You can only have one default gateway.

It sounds to me like you want to use both interfaces, which are both
on the same subnet and would connect to the same gateway, as some sort
of load-balanced network, where traffic is evenly distributed across
both interfaces?  Or did I mis-read your initial question?


No, there is no load-balancing
It is a server on the LAN with two NICs, two IPs and I want to access 
the internet on both interfaces ... which means, practically, different 
WAN connection, but from the server's point of view doesn't matter, the 
routing to different WAN is a job of gateway's.

And as I said in the initial message I achieved this ... :)
The question is how can I achieve this with more elegant way, because 
the "route" command is deprecated anyway.


So, again:
Centos 7
2 NICs
enp2s0-192.168.1.12
enp3s0-192.168.1.13
default gateway on enp2s0 is 192.168.1.1, defined in /etc/sysconfig/network

Which other way (preferred with "ip route") can I add this, but:
#route add default gw 192.168.1.1 dev enp3s0


Thanks
Levi

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Re: [CentOS] Gateway question

[Gordon Messmer]

On 08/08/2016 04:05 AM, Levente Birta wrote:
Can I add this in any config files (ex: route-enp2s0)? 



Yes.  Add a route file for each interface, and set up rules to send 
packets out the corresponding physical interface:


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

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Re: [CentOS] Gateway question

[Jonathan Billings]

On Tue, Aug 09, 2016 at 10:58:40AM +0300, Levente Birta wrote:
> What I don't understand why the route command allow to add a second default
> gateway with different interface, but the ip route command doesn't?

You can only have one default gateway.

It sounds to me like you want to use both interfaces, which are both
on the same subnet and would connect to the same gateway, as some sort
of load-balanced network, where traffic is evenly distributed across
both interfaces?  Or did I mis-read your initial question?

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Re: [CentOS] Gateway question

[Levente Birta]

On 09/08/2016 06:56, Anthony K wrote:

On 08/08/16 21:05, Levente Birta wrote:


But how can I add achieve this only with ip route command ... without
route?
Can I add this in any config files (ex: route-enp2s0)?


Hi Levente.

The iproute2 man page for each command is rather well documented on
CentOS 7.  For instance, to view the specifics of *ip route*, type *man
ip-route*.  On older versions of CentOS, all commands to ip have been
lumped into *m**an ip*.

Also, would you care to explain why you'd want to have the same subnet
on 2 interfaces of the same device?  If both networks had a host with
the same IP, and another host on either one of the networks needed to
talk to one of them, how would the router know which one to talk to?

I have encountered this before where one company acquired another and
they both had same subnet IP's.  Before we renumbered one of the
subnets, we resolved this via iptables mungling and policy routing.  So,
it's doable, but why when there's plentiful supply of RFC1918 IP addresses?




As I said in the initial message the centos box need to access the 
internet on both interfaces, the gateway in function of source IP ( the 
two IPs allocated on the centos box on two interfaces ) route the 
traffic on different WAN connection.


My problem simply is that on the Centos box I cannot access the internet 
on the second interface (i.e. second WAN connection) without the 
command: #route add default gw 192.168.1.1 dev enp3s0


I'd like to mention that any traffic on the LAN is going in/out on the 
right interface ... just the internet cannot be reached on the second 
interface.


What I don't understand why the route command allow to add a second 
default gateway with different interface, but the ip route command doesn't?


Thanks

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Re: [CentOS] Gateway question

[Anthony K]

On 08/08/16 21:05, Levente Birta wrote:


But how can I add achieve this only with ip route command ... without 
route?

Can I add this in any config files (ex: route-enp2s0)?


Hi Levente.

The iproute2 man page for each command is rather well documented on 
CentOS 7.  For instance, to view the specifics of *ip route*, type *man 
ip-route*.  On older versions of CentOS, all commands to ip have been 
lumped into *m**an ip*.


Also, would you care to explain why you'd want to have the same subnet 
on 2 interfaces of the same device?  If both networks had a host with 
the same IP, and another host on either one of the networks needed to 
talk to one of them, how would the router know which one to talk to?


I have encountered this before where one company acquired another and 
they both had same subnet IP's.  Before we renumbered one of the 
subnets, we resolved this via iptables mungling and policy routing.  So, 
it's doable, but why when there's plentiful supply of RFC1918 IP addresses?



Regards,
ak.

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Re: [CentOS] Gateway question

[Levente Birta]

On 08/08/2016 14:22, Ashish Yadav wrote:

Hi,

You can define your default gateway in "/etc/sysconfig/network" file,

GATEWAY="192.168.1.1"

After that, restart network services.

# systemctl restart network




It's defined  and it is in routing table ... the only thing added is:
#route add default gw 192.168.1.1 dev enp3s0

Basically I have 2 default gateways or, if you wish, the same gateway is 
defined as default but on different interface


# ip route show
>> default via 192.168.1.1 dev enp3s0
>> default via 192.168.1.1 dev enp2s0
>> 169.254.0.0/16 dev enp2s0  scope link  metric 1002
>> 169.254.0.0/16 dev enp3s0  scope link  metric 1003
>> 192.168.1.0/24 dev enp2s0  proto kernel  scope link  src 192.168.1.12
>> 192.168.1.0/24 dev enp3s0  proto kernel  scope link  src 192.168.1.13




--Regards
Ashishkumar S. Yadav

On Mon, Aug 8, 2016 at 4:35 PM, Levente Birta  wrote:


Hi

There is a Centos 7 up-to-date box with 2 interfaces, let's say
192.168.1.12 - enp2s0, 192.168.1.13 on enp3s0. Default gateway on enp2s0.

The gateway is pfsense, IP is 192.168.1.1 with 2 WAN connections

On the gateway the outgoing traffic is routed by source ip to different
WAN, 192.168.1.12 to WAN1 and 192.168.1.13 to WAN2

On the centos box are set all the route and routing rules:

route-enp2s0:
192.168.1.0/24 dev enp2s0 src 192.168.1.12 table t2
default via 192.168.1.1 dev enp2s0 table t2

route-enp3s0:
192.168.1.0/24 dev enp3s0 src 192.168.1.13 table t3
default via 192.168.1.1 dev enp3s0 table t3

rule-enp2s0:
from 192.168.1.12/32 table t2
to 192.168.1.12/32 table t2

rule-enp3s0:
from 192.168.1.13/32 table t3
to 192.168.1.13/32 table t3


All work when I add
#route add default gw 192.168.1.1 dev enp3s0

And that way I have :

# ip route show
default via 192.168.1.1 dev enp3s0
default via 192.168.1.1 dev enp2s0
169.254.0.0/16 dev enp2s0  scope link  metric 1002
169.254.0.0/16 dev enp3s0  scope link  metric 1003
192.168.1.0/24 dev enp2s0  proto kernel  scope link  src 192.168.1.12
192.168.1.0/24 dev enp3s0  proto kernel  scope link  src 192.168.1.13

But how can I add achieve this only with ip route command ... without
route?
Can I add this in any config files (ex: route-enp2s0)?



Thanks

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Re: [CentOS] Gateway question

[Ashish Yadav]

Hi,

You can define your default gateway in "/etc/sysconfig/network" file,

GATEWAY="192.168.1.1"

After that, restart network services.

# systemctl restart network


--Regards
Ashishkumar S. Yadav

On Mon, Aug 8, 2016 at 4:35 PM, Levente Birta  wrote:

> Hi
>
> There is a Centos 7 up-to-date box with 2 interfaces, let's say
> 192.168.1.12 - enp2s0, 192.168.1.13 on enp3s0. Default gateway on enp2s0.
>
> The gateway is pfsense, IP is 192.168.1.1 with 2 WAN connections
>
> On the gateway the outgoing traffic is routed by source ip to different
> WAN, 192.168.1.12 to WAN1 and 192.168.1.13 to WAN2
>
> On the centos box are set all the route and routing rules:
>
> route-enp2s0:
> 192.168.1.0/24 dev enp2s0 src 192.168.1.12 table t2
> default via 192.168.1.1 dev enp2s0 table t2
>
> route-enp3s0:
> 192.168.1.0/24 dev enp3s0 src 192.168.1.13 table t3
> default via 192.168.1.1 dev enp3s0 table t3
>
> rule-enp2s0:
> from 192.168.1.12/32 table t2
> to 192.168.1.12/32 table t2
>
> rule-enp3s0:
> from 192.168.1.13/32 table t3
> to 192.168.1.13/32 table t3
>
>
> All work when I add
> #route add default gw 192.168.1.1 dev enp3s0
>
> And that way I have :
>
> # ip route show
> default via 192.168.1.1 dev enp3s0
> default via 192.168.1.1 dev enp2s0
> 169.254.0.0/16 dev enp2s0  scope link  metric 1002
> 169.254.0.0/16 dev enp3s0  scope link  metric 1003
> 192.168.1.0/24 dev enp2s0  proto kernel  scope link  src 192.168.1.12
> 192.168.1.0/24 dev enp3s0  proto kernel  scope link  src 192.168.1.13
>
> But how can I add achieve this only with ip route command ... without
> route?
> Can I add this in any config files (ex: route-enp2s0)?
>
>
>
> Thanks
>
> --
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[CentOS] Gateway question

[Levente Birta]

Hi

There is a Centos 7 up-to-date box with 2 interfaces, let's say 
192.168.1.12 - enp2s0, 192.168.1.13 on enp3s0. Default gateway on enp2s0.


The gateway is pfsense, IP is 192.168.1.1 with 2 WAN connections

On the gateway the outgoing traffic is routed by source ip to different 
WAN, 192.168.1.12 to WAN1 and 192.168.1.13 to WAN2


On the centos box are set all the route and routing rules:

route-enp2s0:
192.168.1.0/24 dev enp2s0 src 192.168.1.12 table t2
default via 192.168.1.1 dev enp2s0 table t2

route-enp3s0:
192.168.1.0/24 dev enp3s0 src 192.168.1.13 table t3
default via 192.168.1.1 dev enp3s0 table t3

rule-enp2s0:
from 192.168.1.12/32 table t2
to 192.168.1.12/32 table t2

rule-enp3s0:
from 192.168.1.13/32 table t3
to 192.168.1.13/32 table t3


All work when I add
#route add default gw 192.168.1.1 dev enp3s0

And that way I have :

# ip route show
default via 192.168.1.1 dev enp3s0
default via 192.168.1.1 dev enp2s0
169.254.0.0/16 dev enp2s0  scope link  metric 1002
169.254.0.0/16 dev enp3s0  scope link  metric 1003
192.168.1.0/24 dev enp2s0  proto kernel  scope link  src 192.168.1.12
192.168.1.0/24 dev enp3s0  proto kernel  scope link  src 192.168.1.13

But how can I add achieve this only with ip route command ... without route?
Can I add this in any config files (ex: route-enp2s0)?



Thanks

--
   Levi
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