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man pages section 3: Basic Library Functions

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Updated: Wednesday, July 27, 2022



sctp_bindx - add or remove IP addresses to or from an SCTP socket


cc [ flag... ] file... –lsctp [ library... ]
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/sctp.h>

int sctp_bindx(int sock, void *addrs, int addrcnt, int flags);


The sctp_bindx() function adds or removes addresses to or from an SCTP socket. If sock is an Internet Protocol Version 4 (IPv4) socket, addrs should be an array of sockaddr_in structures containing IPv4 addresses. If sock is an Internet Protocol Version 6 (IPv6) socket, addrs should be an array of sockaddr_in6 structures containing IPv6 or IPv4-mapped IPv6 addresses. The addrcnt is the number of array elements in addrs. The family of the address type is used with addrcnt to determine the size of the array.

The flags parameter is a bitmask that indicates whether addresses are to be added or removed from a socket. The flags parameter is formed by bitwise OR of zero or more of the following flags:


Indicates that addresses from addrs should be added to the SCTP socket.


Indicates that addresses from addrs should be removed from the SCTP socket.

These two flags are mutually exclusive. If flags is formed by a bitwise OR of both SCTP_BINDX_ADD_ADDR and SCTP_BINDX_REM_ADDR, the sctp_bindx() function will fail.

Prior to calling sctp_bindx() on an SCTP endpoint, the endpoint should be bound using bind(3C). On a listening socket, a special INADDR_ANY value for IP or an unspecified address of all zeros for IPv6 can be used in addrs to add all IPv4 or IPv6 addresses on the system to the socket. The sctp_bindx() function can also be used to add or remove addresses to or from an established association. In such a case, messages are exchanged between the SCTP endpoints to update the address lists for that association if both endpoints support dynamic address reconfiguration.

Return Values

Upon successful completion, the sctp_bindx() function returns 0. Otherwise, the function returns -1 and sets errno to indicate the error.


The sctp_bindx() call fails under the following conditions.


The sock argument is an invalid file descriptor.


The sock argument is not a socket.


One or more of the IPv4 or IPv6 addresses is invalid.


The endpoint is not bound.


The last address is requested to be removed from an established association.


See attributes(7) for descriptions of the following attributes:

Interface Stability

See Also

listen(3C), bind(3C), sctp_freeladdrs(3C), sctp_freepaddrs(3C), sctp_getladdrs(3C), sctp_getpaddrs(3C), socket(3C), in.h(3HEAD), libsctp(3LIB), inet(4P), inet6(4P), ip(4P), ip6(4P), sctp(4P)


IPv4-mapped addresses are not recommended.