[Dnsmasq-discuss] [PATCH] add --tftp-mtu option to set the MTU for the TFTP server

Simon Kelley simon at thekelleys.org.uk
Tue Mar 1 17:28:35 GMT 2016


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On 28/02/16 10:47, ?? wrote:
> Greetings.
> 
> I think it would be better to be "--tftp-blksize", as this is
> already defined in RFC 2347. If some buggy client said he want
> bigger, the server could reply --tftp-blksize is the maximum.

I think that is a good suggestion.

> 
> In my understanding of TFTP, it would be strange that a client 
> requested a big blksize option then deny fragmented packets. It's
> the client said he want a big one, not the server. Why fix this on 
> server?

Buggy clients happen. We already have the  --tftp-no-blocksize option
for this sort of situation.

> 
> I think it would be a bad idea to request a super big blksize
> option to increase performance. I think the blksize option
> shouldn't bigger than Ethernet MTU. Because there are buggy client
> refusing IPv4 fragment and there is no fragmentation in IPv6. To
> get more speed, the right way is RFC 7440. However RFC 7440 is
> still not widely supported. If writing new code, I think it would
> be better to follow RFC 7440 way, and left those old buggy slow
> client behind.
> 
> Dnsmasq is great~ >_<
> 
> 
> ?? 2016.2
> 
> 
> 
> 

tftp is never going to be fast. Making it work with as many clients as
possible is the best we can hope.

What do people think.

- -tft-blocksize-max instead of --tftp-mtu?


Cheers,

Simon.

> 
> 
> 
>> To: dnsmasq-discuss at lists.thekelleys.org.uk From: 
>> simon at thekelleys.org.uk Date: Wed, 24 Feb 2016 22:06:15 +0000 
>> Subject: Re: [Dnsmasq-discuss] [PATCH] add --tftp-mtu option to
>> set the MTU for the TFTP server
>> 
> Thanks for that.
> 
> 
> I've somewhat reworked it so that the supplied MTU is a ceiling
> (ie, you can reduce the used MTU with the option, but not increase
> it.) That would seem to be safer.
> 
> 
> In the git repo now. Please shout if I've broken things for you.
> 
> 
> 
> cheers,
> 
> Simon.
> 
> 
> On 24/02/16 18:24, Patrick McLean wrote:
>>>> Some BIOSes don't like fragmented packets, and it's useful
>>>> to be able to netboot over MTU limited links, but it's
>>>> annoying to set the interface MTU for only TFTP. This patch
>>>> adds a tftp-mtu option to override getting the MTU from the
>>>> interface.
>>>> 
>>>> 
>>>> 
>>>> _______________________________________________ 
>>>> Dnsmasq-discuss mailing list 
>>>> Dnsmasq-discuss at lists.thekelleys.org.uk 
>>>> http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss
>>>>
>
>>>>
>>>> 
>> 
>> _______________________________________________ Dnsmasq-discuss 
>> mailing list Dnsmasq-discuss at lists.thekelleys.org.uk 
>> http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss
> 
> 
> 
> 
> _______________________________________________ Dnsmasq-discuss 
> mailing list Dnsmasq-discuss at lists.thekelleys.org.uk 
> http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss
> 

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