[MPTCP] Re: [MPTCP][PATCH mptcp-next 1/3] mptcp: add add_addr_echo sysctl

[Geliang Tang <geliangtang at gmail.com>]

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Hi Paolo,

Paolo Abeni <pabeni(a)redhat.com> 于2020年9月23日周三 下午6:26写道：
>
> On Tue, 2020-09-22 at 16:12 +0800, Geliang Tang wrote:
> > This patch added a new sysctl, named add_addr_echo, to control the
> > ADD_ADDR
> > echo ability.
> >
> > Signed-off-by: Geliang Tang <geliangtang(a)gmail.com>
>
> If I read the series correctly, this sysctl is only needed for self-
> test's sake, right? can you instead drop the add_addr packet with some
> netfilter rules ? possibly matching on TCP PROTO, TCP len == 0 and the
> appropriate packet len should be sufficient.

I still have not found the rules that can drop ADD_ADDR packets. But I found
something useful like this:

# iptables -A OUTPUT -p tcp --tcp-option 30 -m length --length 0:100 -j DROP

"tcp-option 30" can match MPTCP packets, and "length" can match the IP
packet's total length. But they are not sufficient.

Could you please give me some suggestions about this? Can I write a new
netfiler module to do this? Is this acceptable?

Thanks.

-Geliang

>
> Disabling the echo would likely violate the RFC, I think that exposing
> this ability to user-space would be too much even for unix
> philosophy[1] ;)
>
> Cheers,
>
> Paolo
>
> [1] http://www.anvari.org/fortune/Miscellaneous_Collections/412232_the-unix-philosophy-basically-involves-giving-you-enough-rope-to-hang-yourself.html
>