From: "Jason A. Donenfeld" <Jason@zx2c4.com>
Date: Thu, 8 Dec 2016 23:20:04 +0100

Hi David,

On Thu, Dec 8, 2016 at 1:37 AM, David Miller [off-list ref] wrote:

quoted

You really have to land the IP header on a proper 4 byte boundary.

I would suggest pushing 3 dummy garbage bytes of padding at the front
or the end of your header.

Are you sure 3 bytes to get 4 byte alignment is really the best? I was
thinking that adding 1 byte to get 2 byte alignment might be better,
since it would then ensure that the subsequent TCP header winds up
being 4 byte aligned. Or is this in fact not the desired trade off,
and so I should stick with the 3 bytes you suggested?

If the IP header is 4 byte aligned, the TCP header will be as well.