DHCP client not getting IP address from Time Warner

[Ask Bjørn Hansen]

Hi everyone,

After years with Speakeasy at home I'm trying out Time Warner Cable  
(we live too far from the CO to get good DSL speeds).

On OS X I plug-in and get an IP from their DHCP server:

        http://dl.getdropbox.com/u/25895/dhcp/dhcp-osx.txt

On FreeBSD their DHCP server seems to just ignore me (but I see lots  
of broadcast replies to 255.255.255.255/ff:ff:ff:ff:ff:ff).  I've  
tried with both the standard dhclient and the isc dhclient from ports.

00:00:24:c9:23:c1 is my FreeBSD box (Soekris 5501 with vr ethernet):
       
        http://dl.getdropbox.com/u/25895/dhcp/dhcp-freebsd.txt

The OS X dump was made with dhcpdump 1.7 and

sudo tcpdump -i en0 -s 1518 -lenx port bootps or port bootpc | ./
dhcpdump

The FreeBSD one with "dhcpdump -i vr1".

Below is a tcpdump of one of the DHCP requests.

Any ideas would be greatly appreciated.


  - ask


15:46:02.424186 00:00:24:c9:23:c1 > ff:ff:ff:ff:ff:ff, ethertype IPv4  
(0x0800), length 342: 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP,  
Request from 00:00:24:c9:23:c1, length 300
        0x0000:  4510 0148 0000 0000 1011 a996 0000 0000
        0x0010:  ffff ffff 0044 0043 0134 43bb 0101 0600
        0x0020:  ea65 7a82 0000 0000 0000 0000 0000 0000
        0x0030:  0000 0000 0000 0000 0000 24c9 23c1 0000
        0x0040:  0000 0000 0000 0000 0000 0000 0000 0000
        0x0050:  0000 0000 0000 0000 0000 0000 0000 0000
        0x0060:  0000 0000 0000 0000 0000 0000 0000 0000
        0x0070:  0000 0000 0000 0000 0000 0000 0000 0000
        0x0080:  0000 0000 0000 0000 0000 0000 0000 0000
        0x0090:  0000 0000 0000 0000 0000 0000 0000 0000
        0x00a0:  0000 0000 0000 0000 0000 0000 0000 0000
        0x00b0:  0000 0000 0000 0000 0000 0000 0000 0000
        0x00c0:  0000 0000 0000 0000 0000 0000 0000 0000
        0x00d0:  0000 0000 0000 0000 0000 0000 0000 0000
        0x00e0:  0000 0000 0000 0000 0000 0000 0000 0000
        0x00f0:  0000 0000 0000 0000 0000 0000 0000 0000
        0x0100:  0000 0000 0000 0000 6382 5363 3501 013d
        0x0110:  0701 0000 24c9 23c1 0c05 6777 2d62 6e37
        0x0120:  0801 1c02 7903 0f06 0cff 0000 0000 0000
        0x0130:  0000 0000 0000 0000 0000 0000 0000 0000
        0x0140:  0000 0000 0000 0000

_______________________________________________
freebsd-net@... mailing list
http://lists.freebsd.org/mailman/listinfo/freebsd-net
To unsubscribe, send any mail to "freebsd-net-unsubscribe@..."

[Aman Jassal]

Hello,

The logs display something that I find very disturbing.
In the dhcpdump log, the DHCPDISCOVER message your interface sends an
erroneous MAC address, there is a "01:" that is added in front of the
actual MAC address of your interface. What is sent in the discover message
is "01:00:..." instead of "00:00:...".

Then what happens explains itself : the DHCP server will send a DHCPOFFER
by using the requesting client's MAC address, but since the given MAC
address is wrong, he broadcasts it (which I don't think is the behaviour
that is expected in normal cases...).

I think this is also why the client doesn't emit a DHCPREQUEST (which is
emitted by the client to confirm that it is choosing the proposed settings
from the server, and implicitly turning down any other offers made by
other servers).

I'll look into it when I get back home (at work right now). If possible :
could you try to connect your Time Warner cable with another interface ?
Or the same one as the one you used under Mac OS X (that way we would see
if we get the same behaviour, regardless of the network interface chosen)
?

Kind regards,


Aman Jassal



Le Mar 3 novembre 2009 16:47, Ask Bjørn Hansen a écrit :

> Hi everyone,
>
>
> After years with Speakeasy at home I'm trying out Time Warner Cable
> (we live too far from the CO to get good DSL speeds).
>
>
> On OS X I plug-in and get an IP from their DHCP server:
>
>
> http://dl.getdropbox.com/u/25895/dhcp/dhcp-osx.txt
>
>
> On FreeBSD their DHCP server seems to just ignore me (but I see lots
> of broadcast replies to 255.255.255.255/ff:ff:ff:ff:ff:ff).  I've tried
> with both the standard dhclient and the isc dhclient from ports.
>
> 00:00:24:c9:23:c1 is my FreeBSD box (Soekris 5501 with vr ethernet):
>
>
> http://dl.getdropbox.com/u/25895/dhcp/dhcp-freebsd.txt
>
>
> The OS X dump was made with dhcpdump 1.7 and
>
>
> sudo tcpdump -i en0 -s 1518 -lenx port bootps or port bootpc | ./ dhcpdump
>
>
> The FreeBSD one with "dhcpdump -i vr1".
>
>
> Below is a tcpdump of one of the DHCP requests.
>
>
> Any ideas would be greatly appreciated.
>
>
>
> - ask
>
>
>
> 15:46:02.424186 00:00:24:c9:23:c1 > ff:ff:ff:ff:ff:ff, ethertype IPv4
> (0x0800), length 342: 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP,
> Request from 00:00:24:c9:23:c1, length 300
> 0x0000:  4510 0148 0000 0000 1011 a996 0000 0000
> 0x0010:  ffff ffff 0044 0043 0134 43bb 0101 0600
> 0x0020:  ea65 7a82 0000 0000 0000 0000 0000 0000
> 0x0030:  0000 0000 0000 0000 0000 24c9 23c1 0000
> 0x0040:  0000 0000 0000 0000 0000 0000 0000 0000
> 0x0050:  0000 0000 0000 0000 0000 0000 0000 0000
> 0x0060:  0000 0000 0000 0000 0000 0000 0000 0000
> 0x0070:  0000 0000 0000 0000 0000 0000 0000 0000
> 0x0080:  0000 0000 0000 0000 0000 0000 0000 0000
> 0x0090:  0000 0000 0000 0000 0000 0000 0000 0000
> 0x00a0:  0000 0000 0000 0000 0000 0000 0000 0000
> 0x00b0:  0000 0000 0000 0000 0000 0000 0000 0000
> 0x00c0:  0000 0000 0000 0000 0000 0000 0000 0000
> 0x00d0:  0000 0000 0000 0000 0000 0000 0000 0000
> 0x00e0:  0000 0000 0000 0000 0000 0000 0000 0000
> 0x00f0:  0000 0000 0000 0000 0000 0000 0000 0000
> 0x0100:  0000 0000 0000 0000 6382 5363 3501 013d
> 0x0110:  0701 0000 24c9 23c1 0c05 6777 2d62 6e37
> 0x0120:  0801 1c02 7903 0f06 0cff 0000 0000 0000
> 0x0130:  0000 0000 0000 0000 0000 0000 0000 0000
> 0x0140:  0000 0000 0000 0000
>
>
> _______________________________________________
> freebsd-net@... mailing list
> http://lists.freebsd.org/mailman/listinfo/freebsd-net
> To unsubscribe, send any mail to "freebsd-net-unsubscribe@..."
>
>

_______________________________________________
freebsd-net@... mailing list
http://lists.freebsd.org/mailman/listinfo/freebsd-net
To unsubscribe, send any mail to "freebsd-net-unsubscribe@..."

[Barney Wolff]

Power-cycle your cable box, leaving it off for a few minutes.
Cable co's seem to check the MAC, and take a while to forget
the previous one.

On Tue, Nov 03, 2009 at 07:47:14AM -0800, Ask Bjrn Hansen wrote:

> Hi everyone,
>
> After years with Speakeasy at home I'm trying out Time Warner Cable  
> (we live too far from the CO to get good DSL speeds).
>
> On OS X I plug-in and get an IP from their DHCP server:
>
> http://dl.getdropbox.com/u/25895/dhcp/dhcp-osx.txt
>
> On FreeBSD their DHCP server seems to just ignore me (but I see lots  
> of broadcast replies to 255.255.255.255/ff:ff:ff:ff:ff:ff).  I've  
> tried with both the standard dhclient and the isc dhclient from ports.

_______________________________________________
freebsd-net@... mailing list
http://lists.freebsd.org/mailman/listinfo/freebsd-net
To unsubscribe, send any mail to "freebsd-net-unsubscribe@..."

[Ask Bjørn Hansen]

On Nov 3, 2009, at 8:21, JASSAL Aman wrote:

> Hello,
>
> The logs display something that I find very disturbing.
> In the dhcpdump log, the DHCPDISCOVER message your interface sends an
> erroneous MAC address, there is a "01:" that is added in front of the
> actual MAC address of your interface. What is sent in the discover  
> message
> is "01:00:..." instead of "00:00:...".

Hi Aman,

Yeah - I should have pointed that out.  I tried forcing it to be  
correct with

interface "vr1" {
   send dhcp-client-identifier 00:00:24:c9:23:c1;
}

to no effect.

http://dl.getdropbox.com/u/25895/dhcp/dhcp-freebsd-2.txt

> Then what happens explains itself : the DHCP server will send a  
> DHCPOFFER
> by using the requesting client's MAC address, but since the given MAC
> address is wrong, he broadcasts it (which I don't think is the  
> behaviour
> that is expected in normal cases...).

I thought the broadcasts were misguided responses to me, too, at first  
-- but looking further I think it's just broadcasting when it's giving  
(or not) IPs to other clients.   I've no idea why it does that.

I only included one, but in http://dl.getdropbox.com/u/25895/dhcp/dhcp-osx.txt 
  you can see that on OS X I get the weird replies to  
ff:ff:ff:ff:ff:ff, too.

I also noticed that OS X adds two extra options in the request:

OPTION:  57 (  2) Maximum DHCP message size 1500
OPTION:  51 (  4) IP address leasetime      7776000 (12w6d)

Just to test how can I make dhclient add those, too?

> I think this is also why the client doesn't emit a DHCPREQUEST  
> (which is
> emitted by the client to confirm that it is choosing the proposed  
> settings
> from the server, and implicitly turning down any other offers made by
> other servers).
>
> I'll look into it when I get back home (at work right now). If  
> possible :
> could you try to connect your Time Warner cable with another  
> interface ?
> Or the same one as the one you used under Mac OS X (that way we  
> would see
> if we get the same behaviour, regardless of the network interface  
> chosen)
> ?

The Soekris box only has vr interfaces; the OS X NIC is in my laptop  
so unless I install FreeBSD on there I won't be able to test  
that. :-)   I did actually try one of the other vr interfaces on the  
Soekris box with the same result (they work fine with isc-dhcp running  
on another FreeBSD box).


  - ask
_______________________________________________
freebsd-net@... mailing list
http://lists.freebsd.org/mailman/listinfo/freebsd-net
To unsubscribe, send any mail to "freebsd-net-unsubscribe@..."

[Ask Bjørn Hansen]

On Nov 3, 2009, at 8:27, Barney Wolff wrote:

> Power-cycle your cable box, leaving it off for a few minutes.
> Cable co's seem to check the MAC, and take a while to forget
> the previous one.

Hah - yeah, I tried that, too.  No difference.  (Plugging in one of  
the macs and then another seems to work fine, too).

Thanks for the idea though.


  - ask
_______________________________________________
freebsd-net@... mailing list
http://lists.freebsd.org/mailman/listinfo/freebsd-net
To unsubscribe, send any mail to "freebsd-net-unsubscribe@..."

[Aman Jassal]

Hello Ask,

Sorry for getting back to you so late T_T...
I've never faced a MAC address problem before, so I must say I was quite
surprised when I saw your logs yesterday evening.

I'm not sure what the nature of the problem exactly is (I didn't have time
to reproduce it yesterday evening either >_<),

I would suggest that you create your own dhclient.conf file (->
/etc/dhclient.conf) and specify the options you want to send in the
DHCPDISCOVER message yourself. The dhclient program starts by reading what
is specified in this file. You could try sending :

send {
    dhcp-client-identifier "your MAC address"
    ip-address "whatever IP address is topologically correct and with the
defined range of address the server can allocate"
}

With this, you clearly specify the MAC and the IP address you are
requesting (it is the parameters in the options field). You can also
specify other parameters if you wish to.
When you forced it, the MAC address was the good one, so that is good sign.

In the last log you sent (dhcp-freebsd-2.txt), the server is sending back
DHCPNAK messages, which occur in only 2 cases : either the client is
requesting an address that is topologically incorrect, or the lease of the
requested address has expired. But this, to me, looks like the DHCP server
was slightly confused about what was going on :)
Just try power-cycling your Time Warner device, so that he doesn't have
any record of any address.

If you specify clearly the options in your dhcpdiscover message by setting
them in the dhclient.conf, there's no reason the DHCP server will reject
your message. Whenever I configure my connection settings manually, I just
type :

# dhclient iwn0

(My interface uses iwn driver), and that works perfectly... I don't even
have a dhclient.conf file !

Hopefully it (setting up dhclient.conf) helps.

Kind regards,


Aman Jassal



Le Mar 3 novembre 2009 18:15, Ask Bjørn Hansen a écrit :
>

> On Nov 3, 2009, at 8:21, JASSAL Aman wrote:
>
>
>> Hello,
>>
>>
>> The logs display something that I find very disturbing.
>> In the dhcpdump log, the DHCPDISCOVER message your interface sends an
>> erroneous MAC address, there is a "01:" that is added in front of the
>> actual MAC address of your interface. What is sent in the discover
>> message is "01:00:..." instead of "00:00:...".
>
> Hi Aman,
>
>
> Yeah - I should have pointed that out.  I tried forcing it to be
> correct with
>
> interface "vr1" { send dhcp-client-identifier 00:00:24:c9:23:c1; }
>
>
> to no effect.
>
> http://dl.getdropbox.com/u/25895/dhcp/dhcp-freebsd-2.txt
>
>
>> Then what happens explains itself : the DHCP server will send a
>> DHCPOFFER
>> by using the requesting client's MAC address, but since the given MAC
>> address is wrong, he broadcasts it (which I don't think is the behaviour
>>  that is expected in normal cases...).
>
> I thought the broadcasts were misguided responses to me, too, at first
> -- but looking further I think it's just broadcasting when it's giving
> (or not) IPs to other clients.   I've no idea why it does that.
>%20
>
> I only included one, but in
> http://dl.getdropbox.com/u/25895/dhcp/dhcp-osx.txt
> you can see that on OS X I get the weird replies to ff:ff:ff:ff:ff:ff, too.
>
>
> I also noticed that OS X adds two extra options in the request:
>
>
> OPTION:  57 (  2) Maximum DHCP message size 1500
> OPTION:  51 (  4) IP address leasetime      7776000 (12w6d)
>
>
> Just to test how can I make dhclient add those, too?
>
>
>>%20I think this is also why the client doesn't emit a DHCPREQUEST
>> (which is
>> emitted by the client to confirm that it is choosing the proposed
>> settings from the server, and implicitly turning down any other offers
>> made by other servers).
>>
>> I'll look into it when I get back home (at work right now). If
>> possible : could you try to connect your Time Warner cable with another
>> interface ? Or the same one as the one you used under Mac OS X %28that way
>> we would see if we get the same behaviour, regardless of the network
>> interface chosen) ?
>>
>
> The Soekris box only has vr interfaces; the OS X NIC is in my laptop
> so unless I install FreeBSD on there I won't be able to test that. :-)   I
> did actually try one of the other vr interfaces on the Soekris box with
> the same result (they work fine with isc-dhcp running on another FreeBSD
> box).
>
>
> - ask
>
>

_______________________________________________
freebsd-net@... mailing list
http://lists.freebsd.org/mailman/listinfo/freebsd-net
To unsubscribe, send any mail to "freebsd-net-unsubscribe@..."

[Philip Paeps]

On 2009-11-03 07:47:14 (-0800), Ask Bjørn Hansen <ask@...> wrote:
> On FreeBSD their DHCP server seems to just ignore me (but I see lots  of
> broadcast replies to 255.255.255.255/ff:ff:ff:ff:ff:ff).  I've  tried with
> both the standard dhclient and the isc dhclient from ports.
>
> 00:00:24:c9:23:c1 is my FreeBSD box (Soekris 5501 with vr ethernet):
>
> http://dl.getdropbox.com/u/25895/dhcp/dhcp-freebsd.txt

According to that log-file, the server is not ignoring you at all.  You are
ignoring the server?  Your client sends a DHCPDISCOVER -- for some reason it
flips a bit in the client identifier, but that doesn't really matter, since
it's just something the client and the server need to agree on -- and the
server broadcasts DHCPOFFERS.  What I'm not seeing here, are DHCPREQUESTs,
which your client needs to send to accept an offer.

Strangely, there are DHCPACKs, which suggests the server has seen a
DHCPREQUEST.

It is very interesting that in the FreeBSD case, the server seems to want to
broadcast it's DHCPOFFER and in the OS X case, it unicasts it.

 - Philip

--
Philip Paeps                                    Please don't Cc me, I am
philip@...                               subscribed to the list.

  A budget is trying to figure out how the family next
  door is doing it.
_______________________________________________
freebsd-net@... mailing list
http://lists.freebsd.org/mailman/listinfo/freebsd-net
To unsubscribe, send any mail to "freebsd-net-unsubscribe@..."

[Ask Bjørn Hansen]

On Nov 3, 2009, at 7:47, Ask Bjørn Hansen wrote:

> On FreeBSD their DHCP server seems to just ignore me (but I see lots of broadcast replies to 255.255.255.255/ff:ff:ff:ff:ff:ff).  I've tried with both the standard dhclient and the isc dhclient from ports.

Hi everyone,

I just wanted to follow-up on my own mail to tell that the problem is "solved".

Cloning the mac address from my mac seemed to work once, but not consistently.

I never found out exactly what the OS X and the FreeBSD dhcp client are doing differently, but after turning off the cable modem again for a longer while the FreeBSD dhcp client got an IP.

For some reason it appears that OS X is able to "move" the IP to another mac address/client much faster; but honestly after getting it working on the FreeBSD box I didn't want to fuzz with it anymore as it's working where I want it now.

Thanks to everyone who helped with suggestions, questions and advice!


 - ask

--
http://develooper.com/ - http://askask.com/


_______________________________________________
freebsd-net@... mailing list
http://lists.freebsd.org/mailman/listinfo/freebsd-net
To unsubscribe, send any mail to "freebsd-net-unsubscribe@..."