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NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | STANDARDS | HISTORY | NOTES | SEE ALSO | COLOPHON |
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getpeername(2) System Calls Manual getpeername(2)
getpeername - get name of connected peer socket
Standard C library (libc, -lc)
#include <sys/socket.h>
int getpeername(int sockfd, struct sockaddr *restrict addr,
socklen_t *restrict addrlen);
getpeername() returns the address of the peer connected to the
socket sockfd, in the buffer pointed to by addr. The addrlen
argument should be initialized to indicate the amount of space
pointed to by addr. On return it contains the actual size of the
name returned (in bytes). The name is truncated if the buffer
provided is too small.
The returned address is truncated if the buffer provided is too
small; in this case, addrlen will return a value greater than was
supplied to the call.
On success, zero is returned. On error, -1 is returned, and errno
is set to indicate the error.
EBADF The argument sockfd is not a valid file descriptor.
EFAULT The addr argument points to memory not in a valid part of
the process address space.
EINVAL addrlen is invalid (e.g., is negative).
ENOBUFS
Insufficient resources were available in the system to
perform the operation.
ENOTCONN
The socket is not connected.
ENOTSOCK
The file descriptor sockfd does not refer to a socket.
POSIX.1-2008.
POSIX.1-2001, SVr4, 4.4BSD (first appeared in 4.2BSD).
For stream sockets, once a connect(2) has been performed, either
socket can call getpeername() to obtain the address of the peer
socket. On the other hand, datagram sockets are connectionless.
Calling connect(2) on a datagram socket merely sets the peer
address for outgoing datagrams sent with write(2) or recv(2). The
caller of connect(2) can use getpeername() to obtain the peer
address that it earlier set for the socket. However, the peer
socket is unaware of this information, and calling getpeername()
on the peer socket will return no useful information (unless a
connect(2) call was also executed on the peer). Note also that
the receiver of a datagram can obtain the address of the sender
when using recvfrom(2).
accept(2), bind(2), getsockname(2), ip(7), socket(7), unix(7)
This page is part of the man-pages (Linux kernel and C library
user-space interface documentation) project. Information about
the project can be found at
⟨https://www.kernel.org/doc/man-pages/⟩. If you have a bug report
for this manual page, see
⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.
This page was obtained from the tarball man-pages-6.15.tar.gz
fetched from
⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on
2025-08-11. If you discover any rendering problems in this HTML
version of the page, or you believe there is a better or more up-
to-date source for the page, or you have corrections or
improvements to the information in this COLOPHON (which is not
part of the original manual page), send a mail to
man-pages@man7.org
Linux man-pages 6.15 2025-05-17 getpeername(2)
Pages that refer to this page: socket(2), socketcall(2), syscalls(2), getnameinfo(3), sockaddr(3type), crypttab(5), systemd.exec(5), signal-safety(7), socket(7), unix(7)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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