Multicast + SLIP + OSPF + gated: any [good] experience?

Multicast + SLIP + OSPF + gated: any [good] experience?

Post by Vitaly V. Fedrushko » Fri, 28 Mar 1997 04:00:00



Good $daytime,

Just caught a problem while setting up leased line.  Setup:

"intranet" - Linux 2.0.29 - 4W LL - Cisco 2511 - Internet
              (firewall)
RIP & RIP-2 gated                              OSPF

So I am about to setup gated to translate routing data between RIP and
OSPF.

Symptom: cannot get gated (gated version R3_5Beta_1 built Sun Dec 17
19:47:11 CST 1995) to see OSPF packets from cisco.  When I turn on
firewall I can see bouncing OSPF (224.0.0.5) packets.  When I accept
them, I apparently can't see them in gated trace file.

Another thing I could not get working is slattach.  I saw no incoming
packets so I moved to DIP to run leased line.  I am running `ifconfig
sl0 multicast` manually after dip.  Are these symptoms related to each
other?

My hypotheses right now are:

1. I am _STUPID_
2. Kernel does not support multicasting on SLIP interfaces
3. Interface running with DIP does not catch multicast packets
4. My gated is missing somewhat in config

Which one should I keep :) ?  Any experience with similar setups would
be of great value for me.  Thanks for your time.

[Please reply also by email, because I have poor newsfeed.  And I'm so
sorry for my horrible English.]

  Regards,
  Willy.

--
"No easy hope or lies        | Vitaly "Willy the Pooh" Fedrushkov
 Shall bring us to our goal, | Computer Science Department,
 But iron sacrifice          | Chelyabinsk State University.

                   R.Kipling |

 
 
 

Multicast + SLIP + OSPF + gated: any [good] experience?

Post by Rick Stanbac » Sat, 29 Mar 1997 04:00:00


I am not sure if gated runs ospf ?  I would normally set up the cisco as a
OSPF boundary router so it will propagate OSPF routes to RIP.  This method
allows you to run RIP on the Linux host.



> Good $daytime,

> Just caught a problem while setting up leased line.  Setup:

> "intranet" - Linux 2.0.29 - 4W LL - Cisco 2511 - Internet
>          (firewall)
> RIP & RIP-2    gated                              OSPF

> So I am about to setup gated to translate routing data between RIP and
> OSPF.

> Symptom: cannot get gated (gated version R3_5Beta_1 built Sun Dec 17
> 19:47:11 CST 1995) to see OSPF packets from cisco.  When I turn on
> firewall I can see bouncing OSPF (224.0.0.5) packets.  When I accept
> them, I apparently can't see them in gated trace file.

> Another thing I could not get working is slattach.  I saw no incoming
> packets so I moved to DIP to run leased line.  I am running `ifconfig
> sl0 multicast` manually after dip.  Are these symptoms related to each
> other?

> My hypotheses right now are:

> 1. I am _STUPID_
> 2. Kernel does not support multicasting on SLIP interfaces
> 3. Interface running with DIP does not catch multicast packets
> 4. My gated is missing somewhat in config

> Which one should I keep :) ?  Any experience with similar setups would
> be of great value for me.  Thanks for your time.

> [Please reply also by email, because I have poor newsfeed.  And I'm so
> sorry for my horrible English.]

>   Regards,
>   Willy.

> --
> "No easy hope or lies        | Vitaly "Willy the Pooh" Fedrushkov
>  Shall bring us to our goal, | Computer Science Department,
>  But iron sacrifice          | Chelyabinsk State University.

>                    R.Kipling |


 
 
 

1. gated OSPF multicast purgatory

I'm trying to implement what I would call a "reverse firewall". Usually a
firewall is designed to both protect a "private" network against unwanted
access from the public Internet, and at the same time to provide access to
services on the Internet from the private network. In a "reverse firewall" the
roles of public vs. private addresses is *reversed*. What would normally be
considered The Unroutable -- RFC 1918 clean private addresses -- is exactly
what one wants to route. "IANA-Public" IP addresses are what you want to
*hide* -- in this case because of a legacy "cowboy network" (which I don't
have political control over, of course) where the cowboys used illicit
cooked-up IP addresses in days of yore, it's too painful to change them all,
but they need the connectivity I've got in my RFC 1918 kosher frame relay
network.

I have a pair of OpenBSD boxen using ipnat and ipf to connect the first two
segments of the cowboys.  It works.  But to make it work I had to give each
box a static route to the other (they share a LAN segment connecting one
interface each.)  This will *not work* on my frame relay network.  I've gotten
routed working fine, but I still can't figure out how to advertise the "NATted
clean" address without advertising the cowyboy addresses, which I want to keep
off my network.

So I'm trying to learn gated and OSPF.  I'm having a hard time.  I haven't
tried to test with sniffing, but it looks to me like the two gated's are
multicasting on opposite interfaces.  The second gated can hear Hello packets
from the first, but the first never receives any back.  I've tried
/etc/rc.conf with multicast_host set to the interface I *want* to be
multicasting, and multicast_router=NO, as well as multicast_host=NO and
multicast_router=YES.  The first machine still can't hear back from the
second. The only difference I've been able to discern between the two machines
is that the first machine sees the politically correct interface as the first
interface, but the second machine sees the cowyboy interface as the first
interface -- reading from autoprobe results in /var/log/messages when it
boots.

Help!  I gather gated wants to do its own thing setting up a route for
multicasting.  If you've gotten this kind of thing to work, I'd love to hear
how.

Perhaps a simpler question.  Say I have two interfaces, call them xl0 and xl1.
Traffic on xl0 gets NATted when it goes out xl1.  I want xl0 to act from
routed as a passive interface, but I *do* want to advertise the NATted route.  
This seems like it should be simple, but I can't get it to work.  When I give
routed an explicit subnet= in /etc/gateways, it always comes back with bad
entry.  Is there a simple way to advertise a NAT route which is tied to a
passive interface?

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