[LARTC] bridge or vlan

[LARTC] bridge or vlan

[Vaidas M]

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Hello to everyone,

 

Here is the situation:

[LAN1]---[eth3]/----------\

               | LinuxBR  |[eth2]---[LAN0]---[linuxGW]---[internet]

[LAN2]---[eth4]\----------/

Whole LAN is in subnet 10.0.0.0/24.

 

So I need:

LAN0, LAN1, LAN2 could not see each other.

LAN0, LAN1, LAN2 is in same subnet (10.0.0.0/24).

All LANs have to get only internet.

 

How can I configure LinuxBR to do so?

Do I have to do only bridge? Or only vlan? Or both?

 

Thanks.

 

_      _     _    _   _  _ _ __ ___ ____ _____

Vaidas M. [Noxius]

 


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Re: [LARTC] bridge or vlan

[Pan'ko Alexander]

On Sat, 20 Oct 2007 14:23:12 +0300
"Vaidas M" <admin@vdx.lt> wrote:

> Hello to everyone,
> 
>  
> 
> Here is the situation:
> 
> [LAN1]---[eth3]/----------\
> 
>                | LinuxBR  |[eth2]---[LAN0]---[linuxGW]---[internet]
> 
> [LAN2]---[eth4]\----------/
> 
> Whole LAN is in subnet 10.0.0.0/24.
> 
>  
> 
> So I need:
> 
> LAN0, LAN1, LAN2 could not see each other.
> 
> LAN0, LAN1, LAN2 is in same subnet (10.0.0.0/24).
> 
> All LANs have to get only internet.
> 
>  
> 
> How can I configure LinuxBR to do so?
> 
> Do I have to do only bridge? Or only vlan? Or both?
> 

On LinuxBR:
	iptables -A FORWARD -s 10.0.0.0/24 -d linuxGW_IP/32 -j ACCEPT
	iptables -A FORWARD -s 10.0.0.0/24 -d 10.0.0.0/24 -j DROP
	iptables -t nat -A POSTROUTING -s 10.0.0.0/24 -d linuxGW_IP/32 -j MASQUERADE

On linuxGW:
	iptables -t nat -A POSTROUTING -s LinuxBR_IP/32 -j MASQUERADE

-- 
With best regards, Pan'ko Alexander.
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Re: [LARTC] bridge or vlan

[Grant Taylor]

On 10/20/07 06:23, Vaidas M wrote:
> Hello to everyone,
> 
> Here is the situation:
> 
> [LAN1]---[eth3]/----------\
>                | LinuxBR  |[eth2]---[LAN0]---[linuxGW]---[internet]
> [LAN2]---[eth4]\----------/
> 
> Whole LAN is in subnet 10.0.0.0/24.
> 
> So I need:
> 
> LAN0, LAN1, LAN2 could not see each other.
> LAN0, LAN1, LAN2 is in same subnet (10.0.0.0/24).
> 
> All LANs have to get only internet.
> 
> How can I configure LinuxBR to do so?
> 
> Do I have to do only bridge? Or only vlan? Or both?

This is very simple to do.  Bridge all your LANs together (what ever 
interface you choose to use, physical and / or VLAN) and use EBTables to 
block forwarding of any traffic that has a source and destination on 
your 10.0.0.0/24 network.  This will allow traffic from the LAN to the 
world and from the world to the LAN to be bridged, but not allow LAN to 
LAN traffic to be bridged.

ebtables -t filter -A FORWARD --ip-src 10/24 --ip-dst 10/24 -j DROP

This will block all IP traffic.  Broadcasts and ARPs will get through, 
but can be stopped if you do want.  If you do want broadcasts and ARPs 
to be stopped let me know and I'll propose some follow up rules to add 
to the above to stop them.



Grant. . . .
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Re: [LARTC] bridge or vlan

[Grant Taylor]

On 10/22/07 15:50, Vaidas M wrote:
> Thanks for your answer, this would help.

You are welcome.

> I think I know how to block arp: -p ARP -j DROP something like that, 
> ant the broadcasts: --pkttype-type ...

Be careful blocking all ARP / broadcasts.  Remember that equipment will 
need to ARP to find the router, at least from the two LANs that are not 
common with the router.

You will probably want to allow ARPs to the router's IP address (and any 
other common equipment) and block all others.



Grant. . . .
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