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| 14 | <H1>Arptables Frequently (and less frequently) Asked Questions</H1> |
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| 16 | <A name="top"></A> |
| 17 | <P>Last modified: December 30, 2003</P> |
| 18 | <DL> |
| 19 | <DT> |
| 20 | Why does arptables have 2 chains on a 2.4 kernel and 3 chains |
| 21 | on a 2.6 kernel? |
| 22 | </DT> |
| 23 | <DD> |
| 24 | The 2.4 kernel doesn't have the arptables FORWARD chain as 2.4 |
| 25 | kernels can't filter bridged ARP traffic. |
| 26 | </DD> |
| 27 | <DT> |
| 28 | When is the bridged ARP traffic seen by arptables? |
| 29 | </DT> |
| 30 | <DD> |
| Bart De Schuymer | 2a72ba3 | 2004-03-21 13:30:20 +0000 | [diff] [blame] | 31 | The arptables FORWARD chain sees all ARP packets that are being |
| Bart De Schuymer | 5c8b248 | 2003-12-30 19:07:25 +0000 | [diff] [blame] | 32 | bridged, it sees no other traffic. |
| 33 | </DD> |
| 34 | <DT> |
| 35 | What about ARP packets that arrive through a bridge port and |
| 36 | are delivered to the bridge's local ARP stack? |
| 37 | </DT> |
| 38 | <DD> |
| 39 | They are seen in the arptables INPUT chain and have as input |
| 40 | device the logical bridge device, unless you broute them |
| 41 | using ebtables. Brouted packets will have the physical bridge |
| 42 | port as input device. |
| 43 | </DD> |
| 44 | <DT> |
| 45 | What about locally generated ARP packets that leave the bridge |
| 46 | through a logical bridge device? |
| 47 | </DT> |
| 48 | <DD> |
| 49 | They are seen in the arptables OUTPUT chain and have as output |
| 50 | device the logical bridge device. |
| 51 | </DD> |
| 52 | </DL> |
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