Syslinux - Nov 2013 - syslinux.efi pxeboot across multiple subnets

Op 2013-11-08 om 10:48 schreef H. Peter Anvin:
> Thank you for posting the pcap files, by the way.  Analyzing them in
> Wireshark is so much nicer than reading the text output of tcpdump.
Fetch the new capture with

 wget -O pcap2.zip http://ge.tt/api/1/files/136167y/0/blob?downlad


The capture[1] shows two[2] TFTP transmissions of sles113/syslinux.efi,
but nothing after that. As if syslinux.efi was crashed.


Groeten
Geert Stappers

Notes
[1] With a snaplength of 96 bytes or something.
    Add -S0 to tcpdump to get the full network packets.
[2] A previous posting says that the repeated transmission
    is an artifact of the firmware.

On 11/08/2013 03:35 PM, Geert Stappers wrote:
> Op 2013-11-08 om 10:48 schreef H. Peter Anvin:
>> Thank you for posting the pcap files, by the way.  Analyzing them in
>> Wireshark is so much nicer than reading the text output of tcpdump.
> 
> Fetch the new capture with
> 
>  wget -O pcap2.zip http://ge.tt/api/1/files/136167y/0/blob?downlad
> 
> 
> The capture[1] shows two[2] TFTP transmissions of sles113/syslinux.efi,
> but nothing after that. As if syslinux.efi was crashed.
> 
> Groeten
> Geert Stappers
> 
> Notes
> [1] With a snaplength of 96 bytes or something.
>     Add -S0 to tcpdump to get the full network packets.
> [2] A previous posting says that the repeated transmission
>     is an artifact of the firmware.
syslinux.efi either crashed or just can't get packets out.  Either of
which is bad, obviously.
	
	-hpa

I tried the patch from hpa directly on branch firmware and I get a
different (non-working) behavior.
syslinux.efi is correctly downloaded and my tftp server receive
requests for ldlinux.e64 and acknowledge options, but receive no
response at all.

Actually, what happen is that before any packet is actually sent (and
Transmit is called), GetModeData return a StationPort = 0. Leading to
received packets being discarded by the firmware because of the
non-matching port and the absence of AcceptAnyPort flag.
Local port, thus, can't be saved before the first call to
core_udp_send or core_udp_sendto.

Two possible solutions I see:
1) Handle the local port "by hand" instead of relying on the EFI
implementation to chose it.
2) Save the StationPort as soon as it is known similarly to what is
currently done.

2013/11/9, H. Peter Anvin <hpa at zytor.com>:
> On 11/08/2013 03:35 PM, Geert Stappers wrote:
>> Op 2013-11-08 om 10:48 schreef H. Peter Anvin:
>>> Thank you for posting the pcap files, by the way.  Analyzing them
in
>>> Wireshark is so much nicer than reading the text output of tcpdump.
>>
>> Fetch the new capture with
>>
>>  wget -O pcap2.zip http://ge.tt/api/1/files/136167y/0/blob?downlad
>>
>>
>> The capture[1] shows two[2] TFTP transmissions of sles113/syslinux.efi,
>> but nothing after that. As if syslinux.efi was crashed.
>>
>> Groeten
>> Geert Stappers
>>
>> Notes
>> [1] With a snaplength of 96 bytes or something.
>>     Add -S0 to tcpdump to get the full network packets.
>> [2] A previous posting says that the repeated transmission
>>     is an artifact of the firmware.
>
> syslinux.efi either crashed or just can't get packets out.  Either of
> which is bad, obviously.
> 	
> 	-hpa
>
>
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Op 2013-11-08 om 15:44 schreef H. Peter Anvin:
> On 11/08/2013 03:35 PM, Geert Stappers wrote:
> > Op 2013-11-08 om 10:48 schreef H. Peter Anvin:
> >> Thank you for posting the pcap files, by the way.  Analyzing them
in
> >> Wireshark is so much nicer than reading the text output of
tcpdump.
> > 
> > Fetch the new capture with
> > 
> >  wget -O pcap2.zip http://ge.tt/api/1/files/136167y/0/blob?downlad
> > 
> > The capture[1] shows two TFTP transmissions of sles113/syslinux.efi,
> > but nothing after that. As if syslinux.efi was crashed.
> > 
> > [1] With a snaplength of 96 bytes or something.
> >     Add -S0 to tcpdump to get the full network packets.
> 
> syslinux.efi either crashed or just can't get packets out.  Either of
> which is bad, obviously.
And a thrid option, still bad: Send out packets didn't get across gateway.

That is possible when the mirror port is at the same side of a gateway
as the TFTP server is. Euh, I mean visible where I said possible.

Please confirm where in the network the tcpdump is made,
or even better: capture the packets near the booting machine.

Something else: How many gateway / routers are involved?


Groeten
Geert Stappers
Yes, it is good to respect the discussion order
-- 
Leven en laten leven