IP_ROUTER_ALERT(2const) — Linux manual page

IP_ROUTER_ALERT(2const)                           IP_ROUTER_ALERT(2const)

NAME         top

       IP_ROUTER_ALERT - pass all to-be forwarded packets

LIBRARY         top

       Standard C library (libc, -lc)

SYNOPSIS         top

       #include <netinet/in.h>  /* Definition of IP* constants */
       #include <sys/socket.h>

       int setsockopt(int sockfd, IPPROTO_IP, IP_ROUTER_ALERT,
                      const int *enable, sizeof(int));

DESCRIPTION         top

       Pass all to-be forwarded packets with the IP Router Alert option
       set to this socket.

       Valid only for raw sockets.

       This is useful, for instance, for user-space RSVP daemons.

ERRORS         top

       See IPPROTO_IP(2const).  See setsockopt(2).  See ip(7).

STANDARDS         top

       Linux.

HISTORY         top

       Linux 2.2.

CAVEATS         top

       The tapped packets are not forwarded by the kernel; it is the
       user's responsibility to send them out again.

       Socket binding is ignored, such packets are filtered only by
       protocol.

SEE ALSO         top

       IPPROTO_IP(2const), setsockopt(2), ip(7)

COLOPHON         top

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Linux man-pages 6.18            2025-11-25        IP_ROUTER_ALERT(2const)

Pages that refer to this page: IPPROTO_IP(2const)

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