Re: [LEDE-DEV] DHCP via bridge in case of IPv4

2016-08-15 Thread Alexey Brodkin 
Hello,

On Mon, 2016-07-11 at 06:15 +, Alexey Brodkin wrote:
> Hi Russel,
> 
> On Sun, 2016-07-10 at 00:19 -0700, Russell Senior wrote:
> > 
> > > > > > > "Alexey" == Alexey Brodkin  writes:
> > Alexey> Hi Aaron,
> > Alexey> On Sat, 2016-07-09 at 07:47 -0400, Aaron Z wrote:
> > > 
> > > > On Sat, Jul 9, 2016 at 4:37 AM, Alexey Brodkin
> > > >  wrote:
> > > > > 
> > > > > Hello,
> > > > > 
> > > > > I was playing with quite simple bridged setup on different boards
> > > > with > very recent kernels (4.6.3 as of this writing) and found one
> > > > interesting > behavior that I cannot yet understand and googling
> > > > din't help here as well.
> > > > > 
> > > > > My setup is pretty simple: >
> > > > -   --   -
> > > > > 
> > > > > > HOST  |   | "Dumb AP"  |   | Wireless
> > > > client   | > > with DHCP |<->(eth0) (wlan0)<->|
> > > > attempting to | > > server|   |\ br0
> > > > / |   | get settings via DHCP | >
> > > > -   --   -
> > > > > * HOST is my laptop with DHCP server that works for sure.  > *
> > > > "Dumb AP" is a separate board (I tried ARM-based Wandboard and
> > > > ARC-based >   AXS10x boards but results are exactly the same) with
> > > > wired (eth0) and wireless >   (wlan0) network controllers bridged
> > > > together (br0). That "br0" bridge flawlessly >   gets its settings
> > > > from DHCP server on host.  > * Wireless client could be either a
> > > > smatrphone or another laptop etc but >   what's important it should
> > > > be configured to get network settings by DHCP as well.
> > > > > 
> > > > > So what happens "br0" always gets network settings from DHCP server
> > > > on HOST.  > That's fine. But wireless client only reliably gets
> > > > settings from DHCP server > if IPv6 is enabled on "Dumb AP" board. If
> > > > IPv6 is disabled I may see that > wireless client sends "DHCP
> > > > Discover" then server replies with "DHCP Offer" but > that offer
> > > > never reaches wireless client.
> > > > 
> > > > Do you have WDS enabled? If not, DHCP has issues in that scenario:
> > > > https://wiki.openwrt.org/doc/howto/clientmode
> > If the Dumb AP's wireless interface is in ap-mode, then this shouldn't
> > be an issue.  It's only client-mode interfaces that have trouble with 
> > bridging.
> > 
> > I'd suggest running tcpdump on the Dumb AP's wireless interface and the
> > client's wireless interface and see which of them sees the various parts
> > of the DHCP handshake.
> 
> So I did but for DHCP server and wireless client (had no tcpdump on Dump AP
> at the moment).
> 
> That's what I see on the server:
> ->8---
> No. TimeSource Destination  Protocol Length Info
>  3 0.151181000  0.0.0.0255.255.255.255  DHCP 342DHCP Discover - 
> Transaction ID 0x31dc321f
> 11 2.760796000  10.42.0.1  10.42.0.13   DHCP 342DHCP Offer- 
> Transaction ID 0x31dc321f
> 14 5.220985000  0.0.0.0255.255.255.255  DHCP 342DHCP Discover - 
> Transaction ID 0x31dc321f
> 15 5.22115  10.42.0.1  10.42.0.13   DHCP 342DHCP Offer- 
> Transaction ID 0x31dc321f
> 23 15.649835000 0.0.0.0255.255.255.255  DHCP 342DHCP Discover - 
> Transaction ID 0x31dc321f
> 24 15.650017000 10.42.0.1  10.42.0.13   DHCP 342DHCP Offer- 
> Transaction ID 0x31dc321f
> 32 25.648589000 0.0.0.0255.255.255.255  DHCP 342DHCP Discover - 
> Transaction ID 0x31dc321f
> 33 25.648758000 10.42.0.1  10.42.0.13   DHCP 342DHCP Offer- 
> Transaction ID 0x31dc321f
> 43 35.864567000 0.0.0.0255.255.255.255  DHCP 342DHCP Discover - 
> Transaction ID 0x31dc321f
> 48 38.832837000 10.42.0.1  10.42.0.13   DHCP 342DHCP Offer- 
> Transaction ID 0x31dc321f
> ->8---
> 
> That's on the wireless client:
> ->8---
> No.  Time   Source   Destination  Protocol Length Info
> 1171 94.192971000   0.0.0.0  255.255.255.255  DHCP 342DHCP Discover - 
> Transaction ID 0x31dc321f
> 1182 99.263686000   0.0.0.0  255.255.255.255  DHCP 342DHCP Discover - 
> Transaction ID 0x31dc321f
> 1185 109.692642000  0.0.0.0  255.255.255.255  DHCP 342DHCP Discover - 
> Transaction ID 0x31dc321f
> 1186 119.691474000  0.0.0.0  255.255.255.255  DHCP 342DHCP Discover - 
> Transaction ID 0x31dc321f
> 1190 129.907507000  0.0.0.0  255.255.255.255  DHCP 342DHCP Discover - 
> Transaction ID 0x31dc321f
> ->8---
> 
> I'll try to capture data from Dumb AP sometime soon and will reply to the 
> thread.

So finally after quite some time I figured out what

Re: [LEDE-DEV] DHCP via bridge in case of IPv4

2016-07-11 Thread Alexey Brodkin 
Hi Russel,

On Sun, 2016-07-10 at 00:19 -0700, Russell Senior wrote:
> > 
> > > 
> > > > 
> > > > > 
> > > > > > 
> > > > > > "Alexey" == Alexey Brodkin  writes:
> Alexey> Hi Aaron,
> Alexey> On Sat, 2016-07-09 at 07:47 -0400, Aaron Z wrote:
> > 
> > > 
> > > On Sat, Jul 9, 2016 at 4:37 AM, Alexey Brodkin
> > >  wrote:
> > > > 
> > > > 
> > > > Hello,
> > > > 
> > > > I was playing with quite simple bridged setup on different boards
> > > with > very recent kernels (4.6.3 as of this writing) and found one
> > > interesting > behavior that I cannot yet understand and googling
> > > din't help here as well.
> > > > 
> > > > 
> > > > My setup is pretty simple: >
> > > -   --   -
> > > > 
> > > > > 
> > > > > 
> > > > > HOST  |   | "Dumb AP"  |   | Wireless
> > > client   | > > with DHCP |<->(eth0) (wlan0)<->|
> > > attempting to | > > server|   |\ br0
> > > / |   | get settings via DHCP | >
> > > -   --   -
> > > > 
> > > > 
> > > > * HOST is my laptop with DHCP server that works for sure.  > *
> > > "Dumb AP" is a separate board (I tried ARM-based Wandboard and
> > > ARC-based >   AXS10x boards but results are exactly the same) with
> > > wired (eth0) and wireless >   (wlan0) network controllers bridged
> > > together (br0). That "br0" bridge flawlessly >   gets its settings
> > > from DHCP server on host.  > * Wireless client could be either a
> > > smatrphone or another laptop etc but >   what's important it should
> > > be configured to get network settings by DHCP as well.
> > > > 
> > > > 
> > > > So what happens "br0" always gets network settings from DHCP server
> > > on HOST.  > That's fine. But wireless client only reliably gets
> > > settings from DHCP server > if IPv6 is enabled on "Dumb AP" board. If
> > > IPv6 is disabled I may see that > wireless client sends "DHCP
> > > Discover" then server replies with "DHCP Offer" but > that offer
> > > never reaches wireless client.
> > > 
> > > 
> > > Do you have WDS enabled? If not, DHCP has issues in that scenario:
> > > https://wiki.openwrt.org/doc/howto/clientmode
> If the Dumb AP's wireless interface is in ap-mode, then this shouldn't
> be an issue.  It's only client-mode interfaces that have trouble with 
> bridging.
> 
> I'd suggest running tcpdump on the Dumb AP's wireless interface and the
> client's wireless interface and see which of them sees the various parts
> of the DHCP handshake.

So I did but for DHCP server and wireless client (had no tcpdump on Dump AP
at the moment).

That's what I see on the server:
->8---
No. TimeSource Destination  Protocol Length Info
 3 0.151181000  0.0.0.0255.255.255.255  DHCP 342DHCP Discover - 
Transaction ID 0x31dc321f
11 2.760796000  10.42.0.1  10.42.0.13   DHCP 342DHCP Offer- 
Transaction ID 0x31dc321f
14 5.220985000  0.0.0.0255.255.255.255  DHCP 342DHCP Discover - 
Transaction ID 0x31dc321f
15 5.22115  10.42.0.1  10.42.0.13   DHCP 342DHCP Offer- 
Transaction ID 0x31dc321f
23 15.649835000 0.0.0.0255.255.255.255  DHCP 342DHCP Discover - 
Transaction ID 0x31dc321f
24 15.650017000 10.42.0.1  10.42.0.13   DHCP 342DHCP Offer- 
Transaction ID 0x31dc321f
32 25.648589000 0.0.0.0255.255.255.255  DHCP 342DHCP Discover - 
Transaction ID 0x31dc321f
33 25.648758000 10.42.0.1  10.42.0.13   DHCP 342DHCP Offer- 
Transaction ID 0x31dc321f
43 35.864567000 0.0.0.0255.255.255.255  DHCP 342DHCP Discover - 
Transaction ID 0x31dc321f
48 38.832837000 10.42.0.1  10.42.0.13   DHCP 342DHCP Offer- 
Transaction ID 0x31dc321f
->8---

That's on the wireless client:
->8---
No.  Time   Source   Destination  Protocol Length Info
1171 94.192971000   0.0.0.0  255.255.255.255  DHCP 342DHCP Discover - 
Transaction ID 0x31dc321f
1182 99.263686000   0.0.0.0  255.255.255.255  DHCP 342DHCP Discover - 
Transaction ID 0x31dc321f
1185 109.692642000  0.0.0.0  255.255.255.255  DHCP 342DHCP Discover - 
Transaction ID 0x31dc321f
1186 119.691474000  0.0.0.0  255.255.255.255  DHCP 342DHCP Discover - 
Transaction ID 0x31dc321f
1190 129.907507000  0.0.0.0  255.255.255.255  DHCP 342DHCP Discover - 
Transaction ID 0x31dc321f
->8---

I'll try to capture data from Dumb AP sometime soon and will reply to the 
thread.

-Alexey
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Re: [LEDE-DEV] DHCP via bridge in case of IPv4

2016-07-09 Thread Aaron Z 
On Sat, Jul 9, 2016 at 4:37 AM, Alexey Brodkin
 wrote:
> Hello,
>
> I was playing with quite simple bridged setup on different boards with
> very recent kernels (4.6.3 as of this writing) and found one interesting
> behavior that I cannot yet understand and googling din't help here as well.
>
> My setup is pretty simple:
> -   --   -
> | HOST  |   | "Dumb AP"  |   | Wireless client   |
> | with DHCP |<->(eth0) (wlan0)<->| attempting to |
> | server|   |\ br0 / |   | get settings via DHCP |
> -   --   -
>
> * HOST is my laptop with DHCP server that works for sure.
> * "Dumb AP" is a separate board (I tried ARM-based Wandboard and ARC-based
>   AXS10x boards but results are exactly the same) with wired (eth0) and 
> wireless
>   (wlan0) network controllers bridged together (br0). That "br0" bridge 
> flawlessly
>   gets its settings from DHCP server on host.
> * Wireless client could be either a smatrphone or another laptop etc but
>   what's important it should be configured to get network settings by DHCP as 
> well.
>
> So what happens "br0" always gets network settings from DHCP server on HOST.
> That's fine. But wireless client only reliably gets settings from DHCP server
> if IPv6 is enabled on "Dumb AP" board. If IPv6 is disabled I may see that
> wireless client sends "DHCP Discover" then server replies with "DHCP Offer" 
> but
> that offer never reaches wireless client.
Do you have WDS enabled? If not, DHCP has issues in that scenario:
https://wiki.openwrt.org/doc/howto/clientmode

Aaron Z

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