packets to local addresses

packets to local addresses

[MKS]

Hello list

I have a scenario the a computer has 2 PPP connections, where the
computer is the ppp client.

$ifconfig

ppp0   inet  10.0.0.1 p-t-p  192.168.1.1 mask 255.255.255.255

ppp1 inet  10.0.1.1 p-t-p 192.168.1.1 mask  255.255.255.255

for testing purpuses I want packets from ppp0 to ppp1 to actually go
over the physical connection

e.g.

ping  10.0.0.1 -I ppp1 should send the packet over the ppp1 (and out
underlyging physical interface eth0) and it should arrive on the ppp0
interface. (routing is taken care of at the ppp server)

This proably isn't a netfilter issue(?) but I was hoping that some
networking guru would have a solution for me;)

route
Destionation     Gateway      Genmask       iface
  192.168.1.1              *            255.255.255.255  ppp0
 192.168.1.1              *            255.255.255.255   ppp1
0.0.0.0                      *             0.0.0.0                  ppp0
0.0.0.0                      *              0.0.0.0                  ppp1

regards

Mks

Re: packets to local addresses

[Martijn Lievaart]

MKS wrote:
> Hello list
>
> I have a scenario the a computer has 2 PPP connections, where the
> computer is the ppp client.
>
> $ifconfig
>
> ppp0   inet  10.0.0.1 p-t-p  192.168.1.1 mask 255.255.255.255
>
> ppp1 inet  10.0.1.1 p-t-p 192.168.1.1 mask  255.255.255.255
>
> for testing purpuses I want packets from ppp0 to ppp1 to actually go
> over the physical connection
>
> e.g.
>
> ping  10.0.0.1 -I ppp1 should send the packet over the ppp1 (and out
> underlyging physical interface eth0) and it should arrive on the ppp0
> interface. (routing is taken care of at the ppp server)

The -I flag only changes the source address of the packets, not the 
routing. And as the packet is destined for the machine itself, it goes 
over the loopback interface. Maybe adding the -r flag does what you 
want, but I doubt it.

Hping2 probably can do this:

       -I --interface interface name
              By default on linux and BSD systems hping2 uses default  
routing
              interface.   In  other systems or when there is no default 
route
              hping2 uses the first non-loopback interface.  However  
you  are
              able  to  force  hping2 to use the interface you need 
using this
              option. Note: you don't need to  specify  the  whole  
name,  for
              example  -I  et will match eth0 ethernet0 myet1 et cetera. 
If no
              interfaces match hping2 will try to use lo.

HTH,
M4

Re: packets to local addresses

[MKS]

On 4/6/07, Martijn Lievaart <m@rtij.nl> wrote:
> MKS wrote:
> > Hello list
> >
> > I have a scenario the a computer has 2 PPP connections, where the
> > computer is the ppp client.
> >
> > $ifconfig
> >
> > ppp0   inet  10.0.0.1 p-t-p  192.168.1.1 mask 255.255.255.255
> >
> > ppp1 inet  10.0.1.1 p-t-p 192.168.1.1 mask  255.255.255.255
> >
> > for testing purpuses I want packets from ppp0 to ppp1 to actually go
> > over the physical connection
> >
> > e.g.
> >
> > ping  10.0.0.1 -I ppp1 should send the packet over the ppp1 (and out
> > underlyging physical interface eth0) and it should arrive on the ppp0
> > interface. (routing is taken care of at the ppp server)
>
> The -I flag only changes the source address of the packets, not the
> routing. And as the packet is destined for the machine itself, it goes
> over the loopback interface.

What is the best way to change this behaviour, that is force "general"
packets out a specific interface. iptables route target???

Thanks
MKS

Re: packets to local addresses

[Martijn Lievaart]

MKS wrote:
> What is the best way to change this behaviour, that is force "general"
> packets out a specific interface. iptables route target???

Dunno. Maybe the ROUTE target can be of assistence. As I said earlier, 
hping2 probably can do this.

M4

Re: packets to local addresses

[Jan Engelhardt]

On Apr 7 2007 17:45, Martijn Lievaart wrote:
> MKS wrote:
>> What is the best way to change this behaviour, that is force "general"
>> packets out a specific interface. iptables route target???
>
> Dunno. Maybe the ROUTE target can be of assistence. As I said earlier, hping2
> probably can do this.

Use MARK and iproute2.

Jan
-- 

Re: packets to local addresses

[Pascal Hambourg]

Hello,

Jan Engelhardt a écrit :
>>MKS wrote:
>>
>>>What is the best way to change this behaviour, that is force "general"
>>>packets out a specific interface. iptables route target???
> 
> Use MARK and iproute2.

This won't work for local addresses. The local routing table is looked 
up first in the routing process, before any custom ip rule can be 
examined. So MARK and iproute2 have no effect on the routing of local 
and broadcast addresses.

Re: packets to local addresses

[Martijn Lievaart]

Jan Engelhardt wrote:
> On Apr 7 2007 17:45, Martijn Lievaart wrote:
>   
>> MKS wrote:
>>     
>>> What is the best way to change this behaviour, that is force "general"
>>> packets out a specific interface. iptables route target???
>>>       
>> Dunno. Maybe the ROUTE target can be of assistence. As I said earlier, hping2
>> probably can do this.
>>     
>
> Use MARK and iproute2.
>   

Are you sure? I thought you couldn't overrule the local table.

M4

Re: packets to local addresses

[MKS]

On 4/7/07, Martijn Lievaart <m@rtij.nl> wrote:
> Jan Engelhardt wrote:
> > On Apr 7 2007 17:45, Martijn Lievaart wrote:
> >
> >> MKS wrote:
> >>
> >>> What is the best way to change this behaviour, that is force "general"
> >>> packets out a specific interface. iptables route target???
> >>>
> >> Dunno. Maybe the ROUTE target can be of assistence. As I said earlier, hping2
> >> probably can do this.
> >>
> >
> > Use MARK and iproute2.
> >
>
> Are you sure? I thought you couldn't overrule the local table.

It's not possible to override the local table nor bypass or delete from it.

When I use hping -I ppp0 and ping to 10.0.1.1 (ppp1) then I don't get
any response and I can see that the packet never leaves the system
(tcpdump -i ppp0) and that it never arrives on the NAS (using debug on
the NAS)

Does someone know a trick to override the local routing table? or does
that require hacking the kernel?

Regards MKS

Re: packets to local addresses

[Jan Engelhardt]

On Apr 10 2007 11:52, MKS wrote:
>
> It's not possible to override the local table nor bypass or delete from it.
>
> When I use hping -I ppp0 and ping to 10.0.1.1 (ppp1) then I don't get
> any response and I can see that the packet never leaves the system
> (tcpdump -i ppp0) and that it never arrives on the NAS (using debug on
> the NAS)
>
> Does someone know a trick to override the local routing table? or does
> that require hacking the kernel?

What exactly are you trying to achieve?
To simply test transmission, `ping -I interface -bf 255.255.255.255`
does the job.


Jan
-- 

Re: packets to local addresses

[MKS]

On 4/10/07, Jan Engelhardt <jengelh@linux01.gwdg.de> wrote:
>
> On Apr 10 2007 11:52, MKS wrote:
> >
> > It's not possible to override the local table nor bypass or delete from it.
> >
> > When I use hping -I ppp0 and ping to 10.0.1.1 (ppp1) then I don't get
> > any response and I can see that the packet never leaves the system
> > (tcpdump -i ppp0) and that it never arrives on the NAS (using debug on
> > the NAS)
> >
> > Does someone know a trick to override the local routing table? or does
> > that require hacking the kernel?
>
> What exactly are you trying to achieve?
> To simply test transmission, `ping -I interface -bf 255.255.255.255`
> does the job.

I want to generate load on the NAS by making a traffic matrix over n
ppp connections.
e.g. ppp0 will send traffic to ppp1-pppN, etc.

Regards
MKS

Re: packets to local addresses

[Jan Engelhardt]

On Apr 10 2007 15:53, MKS wrote:
>> 
>> What exactly are you trying to achieve?
>> To simply test transmission, `ping -I interface -bf 255.255.255.255`
>> does the job.
>
> I want to generate load on the NAS by making a traffic matrix over n
> ppp connections.
> e.g. ppp0 will send traffic to ppp1-pppN, etc.

I don't think that's what ppp is for. Use bonding or bridging perhaps.


Jan
--