.\" Copyright, the authors of the Linux man-pages project
.\"
.\" SPDX-License-Identifier: Linux-man-pages-copyleft
.\"
.TH IPV6_RTHDR 2const 2025-12-02 "Linux man-pages 6.17"
.SH NAME
IPV6_RTHDR,
IPV6_AUTHHDR,
IPV6_DSTOPTS,
IPV6_HOPOPTS,
IPV6_FLOWINFO,
IPV6_HOPLIMIT
\-
set the delivery of control messages
for incoming datagrams containing extension headers
.SH LIBRARY
Standard C library
.RI ( libc ,\~ \-lc )
.SH SYNOPSIS
.nf
.BR "#include <netinet/in.h>" "  /* Definition of " IP* " constants */"
.B #include <sys/socket.h>
.P
.BI int\~setsockopt(int\~ sockfd ,\~IPPROTO_IPV6,\~IPV6_RTHDR,
.BI "               const\~int\~*" enable ,\~sizeof(int));
.BI int\~setsockopt(int\~ sockfd ,\~IPPROTO_IPV6,\~IPV6_AUTHHDR,
.BI "               const\~int\~*" enable ,\~sizeof(int));
.BI int\~setsockopt(int\~ sockfd ,\~IPPROTO_IPV6,\~IPV6_DSTOPTS,
.BI "               const\~int\~*" enable ,\~sizeof(int));
.BI int\~setsockopt(int\~ sockfd ,\~IPPROTO_IPV6,\~IPV6_HOPOPTS,
.BI "               const\~int\~*" enable ,\~sizeof(int));
.BI int\~setsockopt(int\~ sockfd ,\~IPPROTO_IPV6,\~IPV6_FLOWINFO,
.BI "               const\~int\~*" enable ,\~sizeof(int));
.BI int\~setsockopt(int\~ sockfd ,\~IPPROTO_IPV6,\~IPV6_HOPLIMIT,
.BI "               const\~int\~*" enable ,\~sizeof(int));
.fi
.SH DESCRIPTION
Set delivery of control messages for incoming datagrams
containing extension headers from the received packet.
.TP
.B IPV6_RTHDR
delivers the routing header.
.TP
.B IPV6_AUTHHDR
delivers the authentication header.
.TP
.B IPV6_DSTOPTS
delivers the destination options.
.TP
.B IPV6_HOPOPTS
delivers the hop options.
.TP
.B IPV6_FLOWINFO
delivers an integer containing the flow ID.
.TP
.B IPV6_HOPLIMIT
delivers an integer containing the hop count of the packet.
.P
The control messages have the same type as the socket option.
.P
All these header options can also be set for outgoing packets
by putting the appropriate control message into the control buffer of
.BR sendmsg (2).
.P
Allowed only for
.B SOCK_DGRAM
or
.B SOCK_RAW
sockets.
.SH ERRORS
See
.BR IPPROTO_IPV6 (2const).
See
.BR setsockopt (2).
See
.BR ipv6 (7).
.SH SEE ALSO
.BR IPPROTO_IPV6 (2const),
.BR setsockopt (2),
.BR cmsg (3),
.BR ipv6 (7)