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Description of problem: The kernel supports TCP_FASTOPEN (the system include files have it, the /proc/sys/net/ipv4/tcp_fastopen magic file exists) but there is no definition of MSG_FASTOPEN (required for applications using the feature to build). Version-Release number of selected component (if applicable): glibc-headers-2.17 How reproducible: 100% Additional info: F24, with glibc-headers-2.23.1 has it present in /usr/include/bits/socket.h
I was attempting to compile a (bleeding-edge development version) of an application which can use TCP Fast Open (RFC 7413). The specific application, Exim, is not delivered by Red Hat but is the globally dominant internet-facing MTA according to one scanning site. TCP Fast Open is also expected to be of interest for general web access (it can remove one roundtrip time; important for shortlived connections).
Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory, and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. https://access.redhat.com/errata/RHSA-2017:1916