IP_MTU(2const)                                                  IP_MTU(2const)

NAME
       IP_MTU - path maximum transmission unit size

LIBRARY
       Standard C library (libc, -lc)

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

       int getsockopt(int sockfd, IPPROTO_IP, IP_MTU,
                      int *val, sizeof(int));

DESCRIPTION
       Retrieve the current known path MTU of the current socket.

       IP_MTU is valid only for getsockopt(2), and can be employed only when
       the socket has been connected.

ERRORS
       See IPPROTO_IP(2const).  See getsockopt(2).  See ip(7).

STANDARDS
       Linux.

HISTORY
       Linux 2.2.

SEE ALSO
       IPPROTO_IP(2const), getsockopt(2), ip(7)

Linux man-pages 6.17              2025-11-25                    IP_MTU(2const)