Copyright for tcp.7:

This man page is Copyright (C) 1999 Andi Kleen <ak@muc.de>.
and Copyright (C) 2008 Michael Kerrisk <mtk.manpages@gmail.com>
Note also that many pieces are drawn from the kernel source file
Documentation/networking/ip-sysctl.txt.

License for tcp.7:

Permission is granted to distribute possibly modified copies
of this page provided the header is included verbatim,
and in case of nontrivial modification author and date
of the modification is added to the header.