[LARTC] routing broadcast messages

[LARTC] routing broadcast messages

[Poltorak Serguei]

Hello.

I would like to route broadcast messages.
For now, if I ping a.b.c.255 from m.n.o.w the packet is passing through
each router, except the last, a.b.c.1 (m.n.o.p, other "external" address)
and only he replys to that packet, but not from a.b.c.1, he does it from
m.n.o.p address (logic, it's the address of the output interface).

simple pic.   a.b.c.0/24--[ a.b.c.1, m.n.o.p ]---m.n.o.w

How can i fix this problem??
It could be very cool tool to know, how many hosts are up in your netS.
Combined with VPN from FreeS/WAN (he transports brdcast as other ip
trafic) makes administration easier.

thanks for help.

PoltoS/

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Re: [LARTC] routing broadcast messages

[bert hubert]

On Wed, Jul 10, 2002 at 04:35:16AM +0400, Poltorak Serguei wrote:
> Hello.
> 
> I would like to route broadcast messages.
> For now, if I ping a.b.c.255 from m.n.o.w the packet is passing through
> each router, except the last, a.b.c.1 (m.n.o.p, other "external" address)
> and only he replys to that packet, but not from a.b.c.1, he does it from
> m.n.o.p address (logic, it's the address of the output interface).

Broadcast messages don't leave their subnet. If you want that, you don't
need a router but a bridge! 

Regards,

bert

-- 
http://www.PowerDNS.com          Versatile DNS Software & Services
http://www.tk                              the dot in .tk
http://lartc.org           Linux Advanced Routing & Traffic Control HOWTO
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Re: [LARTC] routing broadcast messages

[Poltorak Serguei]

Hello

but packets  are going To their subnetwork. then m.n.o.w sends packet to
a.b.c.255 gateways other than a.b.c.1 doesn't know that a.b.c.255 is a
broadcast. it's only a.b.c.1 (m.n.o.p) who discards the packet

may be I should redraw my pic.
  a.b.c.0/24,brd+ -----[ a.b.c.1, m.n.o.p ]-----m.n.o.w
               <-------pings are going in that direction

So, packets are going TO their subnet.

Any idea???

thanks,
PoltoS/

On Wed, 10 Jul 2002, bert hubert wrote:

;On Wed, Jul 10, 2002 at 04:35:16AM +0400, Poltorak Serguei wrote:
;> Hello.
;> 
;> I would like to route broadcast messages.
;> For now, if I ping a.b.c.255 from m.n.o.w the packet is passing through
;> each router, except the last, a.b.c.1 (m.n.o.p, other "external" address)
;> and only he replys to that packet, but not from a.b.c.1, he does it from
;> m.n.o.p address (logic, it's the address of the output interface).
;
;Broadcast messages don't leave their subnet. If you want that, you don't
;need a router but a bridge! 
;
;Regards,
;
;bert
;
;-- 
;http://www.PowerDNS.com          Versatile DNS Software & Services
;http://www.tk                              the dot in .tk
;http://lartc.org           Linux Advanced Routing & Traffic Control HOWTO
;

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Re: [LARTC] routing broadcast messages

[Eran Man]

Hello All,
What your are trying to do is called "directed broadcast", and the linux 
networking gods believe it is evil (i.e. a security hole) and should not 
be implemented by routers. See 
http://www.uwsg.iu.edu/hypermail/linux/net/9707.3/0030.html for example.
		Eran.
Poltorak Serguei wrote:
> Hello
> 
> but packets  are going To their subnetwork. then m.n.o.w sends packet to
> a.b.c.255 gateways other than a.b.c.1 doesn't know that a.b.c.255 is a
> broadcast. it's only a.b.c.1 (m.n.o.p) who discards the packet
> 
> may be I should redraw my pic.
>   a.b.c.0/24,brd+ -----[ a.b.c.1, m.n.o.p ]-----m.n.o.w
>                <-------pings are going in that direction
> 
> So, packets are going TO their subnet.
> 
> Any idea???
> 
> thanks,
> PoltoS/
> 
> On Wed, 10 Jul 2002, bert hubert wrote:
> 
> ;On Wed, Jul 10, 2002 at 04:35:16AM +0400, Poltorak Serguei wrote:
> ;> Hello.
> ;> 
> ;> I would like to route broadcast messages.
> ;> For now, if I ping a.b.c.255 from m.n.o.w the packet is passing through
> ;> each router, except the last, a.b.c.1 (m.n.o.p, other "external" address)
> ;> and only he replys to that packet, but not from a.b.c.1, he does it from
> ;> m.n.o.p address (logic, it's the address of the output interface).
> ;
> ;Broadcast messages don't leave their subnet. If you want that, you don't
> ;need a router but a bridge! 
> ;
> ;Regards,
> ;
> ;bert
> ;
> ;-- 
> ;http://www.PowerDNS.com          Versatile DNS Software & Services
> ;http://www.tk                              the dot in .tk
> ;http://lartc.org           Linux Advanced Routing & Traffic Control HOWTO
> ;
> 
> _______________________________________________
> LARTC mailing list / LARTC@mailman.ds9a.nl
> http://mailman.ds9a.nl/mailman/listinfo/lartc HOWTO: http://lartc.org/
> 



-- 
Eran Mann                 Direct  : 972-4-9936297
Senior Software Engineer  Fax     : 972-4-9890430
Optical Access            Email   : emann@opticalaccess.com




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Re: [LARTC] routing broadcast messages

[Poltorak Serguei]

Hello.

this is Kuznetsov's point of view of 1997 :)
I think it might change. Why not to implement this feature as optional
thing, like syn cookies, that you are to enable. Sometimes this is a
security hole, but sometimes - not. I need this to do a tunnel between two
networks with windoze inside. I don't want to set up a wins or something
else, it's easyer to let broadcast packets traverse through my tunnel,
that need directed broadcast routing. I know, it's a little bit stupid to
support buggy software like netbios, but sometimes it's worth...

PoltoS/

;Hello All,
;What your are trying to do is called "directed broadcast", and the linux 
;networking gods believe it is evil (i.e. a security hole) and should not 
;be implemented by routers. See 
;http://www.uwsg.iu.edu/hypermail/linux/net/9707.3/0030.html for example.
;		Eran.
;Poltorak Serguei wrote:
;> Hello
;> 
;> but packets  are going To their subnetwork. then m.n.o.w sends packet to
;> a.b.c.255 gateways other than a.b.c.1 doesn't know that a.b.c.255 is a
;> broadcast. it's only a.b.c.1 (m.n.o.p) who discards the packet
;> 
;> may be I should redraw my pic.
;>   a.b.c.0/24,brd+ -----[ a.b.c.1, m.n.o.p ]-----m.n.o.w
;>                <-------pings are going in that direction
;> 
;> So, packets are going TO their subnet.
;> 
;> Any idea???
;> 
;> thanks,
;> PoltoS/
;> 
;> On Wed, 10 Jul 2002, bert hubert wrote:
;> 
;> ;On Wed, Jul 10, 2002 at 04:35:16AM +0400, Poltorak Serguei wrote:
;> ;> Hello.
;> ;> 
;> ;> I would like to route broadcast messages.
;> ;> For now, if I ping a.b.c.255 from m.n.o.w the packet is passing through
;> ;> each router, except the last, a.b.c.1 (m.n.o.p, other "external" address)
;> ;> and only he replys to that packet, but not from a.b.c.1, he does it from
;> ;> m.n.o.p address (logic, it's the address of the output interface).
;> ;
;> ;Broadcast messages don't leave their subnet. If you want that, you don't
;> ;need a router but a bridge! 
;> ;
;> ;Regards,
;> ;
;> ;bert
;> ;
;> ;-- 
;> ;http://www.PowerDNS.com          Versatile DNS Software & Services
;> ;http://www.tk                              the dot in .tk
;> ;http://lartc.org           Linux Advanced Routing & Traffic Control HOWTO
;> ;
;> 
;> _______________________________________________
;> LARTC mailing list / LARTC@mailman.ds9a.nl
;> http://mailman.ds9a.nl/mailman/listinfo/lartc HOWTO: http://lartc.org/
;> 
;
;
;
;-- 
;Eran Mann                 Direct  : 972-4-9936297
;Senior Software Engineer  Fax     : 972-4-9890430
;Optical Access            Email   : emann@opticalaccess.com
;
;
;
;

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