I have a GNS3 router that is connected to tap1 in my host. On the other hand, I have an user application connected to tap0 running locally in my host. I can ping both the router and my application. I want my application to talk with the router, so I thought of adding a bridge between tap0 and tap1, like this (using OS X 10.10):

ifconfig bridge1 create addm tap0 addm tap1 up

(see my ifconfig output here).

Wireshark shows that packets sent by my router reach bridge1, however they never reach tap0. I have been trying to solve this for two days now and I am completely lost.

  • This question might be better off on ServerFault. – John WH Smith Nov 6 '14 at 9:20
  • ...or even on Ask Different. Creating and managing bridge network information is highly OS-specific and non -portable and for the purposes of this question, you need a MacOS expert specifically. – Celada Nov 6 '14 at 16:55
  • Reposted on Server Fault. Please do not post the same question on multiple sites — and @JohnWHSmith please do not recommend posting on multiple sites. Nicolás, your question is on-topic here, and I think it's also on-topic on Server Fault, but pick one and delete the other, before they get answered on both sites. – Gilles Nov 7 '14 at 1:28

Assuming the bridge is working[1], you have the two devices connected together at layer two (MAC layer); are both sides on the same layer three (IP) network? Can you describe how "the user application [is] connected to tap0"? (I'm assuming the router in GNS3 is attached to tap1 via a "cloud".)

@Celada, Mac OS X networking is the same as FreeBSD, on which Darwin (the OSS core of Mac OS X) is based; see http://blog.up-link.ro/freebsd-how-to-create-a-network-bridge/ for a simple howto on FreeBSD bridging.

[1] You should see the MAC addr's learned on the bridge by the command output from 'ifconfig bridge0 addr' - by your Gist, you should see '5e:70:93:9c:ae:ce' and 'fe:e4:46:22:2f:cc'

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