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

[Patrick McLean]

On Tue, 1 Mar 2016 17:28:35 +0000
Simon Kelley <simon at thekelleys.org.uk> wrote:

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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.
> > 
> 
> 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?
> 

I am not too picky on the naming of the option, but what would
--tftp-blocksize-max=1300 --tftp-no-blocksize imply?

With mtu, it is obvious that it is using this option where it would
otherwise use the interface mtu, rather than the blocksize.

> 
> 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.
> >