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muse
just joined
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Posts: 5
Joined: Wed Aug 27, 2014 9:59 am

Broadcast between Wan and Lan

Mon Oct 27, 2014 6:08 pm

Hi all,
i just configured an RB450G with some basic nat rules for services running on tcp ports on the private lan side with simple port forwarding rules and all is working good.

I have a device on private lan that supports a network discovery protocol based on a broacast to 255.255.255.255 address
When this device receive that broadcast packet it replies with another broadcast packet to 255.255.255.255.
So i need to enable broacast forwarding from wan to lan and vice versa of udp packets.

I tried with simple nat rules based on dst-nat and src-nat with dst-address = 255.255.255.255, forwarding udp packet to the local ip and the wan side respectively, but it doesn't work..
With wireshark i can't see any packet flowing from wan to lan...
Is there any additional option i forgot to set ??

Thank you,
Bye
 
flipk12
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Posts: 35
Joined: Mon Oct 06, 2014 5:49 pm
Location: Asturias/Spain

Re: Broadcast between Wan and Lan

Tue Oct 28, 2014 9:28 am

Yoy will need to enable proxyarp

From wikipedia ...
Proxy ARP is a technique by which a device on a given network answers the ARP queries for a network address that is not on that network. The ARP Proxy is aware of the location of the traffic's destination, and offers its own MAC address in reply, effectively saying, "send it to me, and I'll get it to where it needs to go." Serving as an ARP Proxy for another host effectively directs LAN traffic to the Proxy. The "captured" traffic is then typically routed by the Proxy to the intended destination via another interface or via a tunnel.
 
muse
just joined
Topic Author
Posts: 5
Joined: Wed Aug 27, 2014 9:59 am

Re: Broadcast between Wan and Lan

Tue Oct 28, 2014 4:10 pm

Yoy will need to enable proxyarp

From wikipedia ...
Proxy ARP is a technique by which a device on a given network answers the ARP queries for a network address that is not on that network. The ARP Proxy is aware of the location of the traffic's destination, and offers its own MAC address in reply, effectively saying, "send it to me, and I'll get it to where it needs to go." Serving as an ARP Proxy for another host effectively directs LAN traffic to the Proxy. The "captured" traffic is then typically routed by the Proxy to the intended destination via another interface or via a tunnel.
Cool, how can i set proxyarp on routeros ?

In the meanwhile i found a temporary workaround ...
at the switch level i configured two rules:

- a rule to redirect traffic from ether1 (WAN) ,that match with discovery protocol (dest. ip 255.255.255.255 and port 50020), to ether2 (private lan, where the device to be discovered is attached)
- a rule to redirect response fron ether2 (where the device discovered is attached) to Ether1 (WAN)



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Now i can discover the device in the local lan from WAN side, but i can't discover any longer the device from local lan :/

Some help ?

Thank you

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