Re: Developing New Socket Option on 4.10

Well, I may have some more socket options in the future for the application
to fill
segments of the 20-byte tag, and the tag may be extended to 40 or 64 bytes,
when
OOB information increases.

How does IPSEC prepend the new header in tunnelling mode? Thanks.

Haisang

On 1/24/06, Chuck Swiger <cswiger@xxxxxxx> wrote:
>
> Haisang Wu wrote:
> > I am writing for help on my freebsd kernel hacking. I am working on
> 4.10,
> > and intend to introduct a new socket option (say, SO_TAG_PAK)
> > for my own kernel. When sending out a packet, if this option is set, the
> > socket layer will produce a 20-byte tag, and finally this tag will be
> > prepended before IP header (may be done in ip_output() ). This is
> somewhat
> > like MPLS's shim layer, but this special packet with the tag will only
> be
> > sent over a logical tunnel to another system. When receiving a packet,
> the
> > IP layer will check whether the packet has this tag (through the
> > first integer of the tag), and pass the tag up (to applications).
>
> If you want to write your own protocol which wraps IP, OK, but there are
> easier
> ways of passing out-of-band data to the application layer.
>
> Consider either setting up a new IP-layer option, a new TCP-layer option,
> or
> just using TCP's urgent pointer to send OOB data. Twenty bytes would fit
> just
> fine inside the existing protocols, and you would be able to take
> advantage of
> hardware support for Rx and Tx checksums, etc, etc.
>
> --
> -Chuck
>
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