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Neither the name of the University nor the names of its contributors 13.\" may be used to endorse or promote products derived from this software 14.\" without specific prior written permission. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26.\" SUCH DAMAGE. 27.\" 28.\" @(#)connect.2 8.1 (Berkeley) 6/4/93 29.\" $FreeBSD$ 30.\" 31.Dd September 29, 2014 32.Dt CONNECT 2 33.Os 34.Sh NAME 35.Nm connect 36.Nd initiate a connection on a socket 37.Sh LIBRARY 38.Lb libc 39.Sh SYNOPSIS 40.In sys/types.h 41.In sys/socket.h 42.Ft int 43.Fn connect "int s" "const struct sockaddr *name" "socklen_t namelen" 44.Sh DESCRIPTION 45The 46.Fa s 47argument 48is a socket. 49If it is of type 50.Dv SOCK_DGRAM , 51this call specifies the peer with which the socket is to be associated; 52this address is that to which datagrams are to be sent, 53and the only address from which datagrams are to be received. 54If the socket is of type 55.Dv SOCK_STREAM , 56this call attempts to make a connection to 57another socket. 58The other socket is specified by 59.Fa name , 60which is an address in the communications space of the socket. 61Each communications space interprets the 62.Fa name 63argument in its own way. 64Generally, stream sockets may successfully 65.Fn connect 66only once; datagram sockets may use 67.Fn connect 68multiple times to change their association. 69Datagram sockets may dissolve the association 70by connecting to an invalid address, such as a null address. 71.Sh RETURN VALUES 72.Rv -std connect 73.Sh ERRORS 74The 75.Fn connect 76system call fails if: 77.Bl -tag -width Er 78.It Bq Er EBADF 79The 80.Fa s 81argument 82is not a valid descriptor. 83.It Bq Er EINVAL 84The 85.Fa namelen 86argument is not a valid length for the address family. 87.It Bq Er ENOTSOCK 88The 89.Fa s 90argument 91is a descriptor for a file, not a socket. 92.It Bq Er EADDRNOTAVAIL 93The specified address is not available on this machine. 94.It Bq Er EAFNOSUPPORT 95Addresses in the specified address family cannot be used with this socket. 96.It Bq Er EISCONN 97The socket is already connected. 98.It Bq Er ETIMEDOUT 99Connection establishment timed out without establishing a connection. 100.It Bq Er ECONNREFUSED 101The attempt to connect was forcefully rejected. 102.It Bq Er ECONNRESET 103The connection was reset by the remote host. 104.It Bq Er ENETUNREACH 105The network is not reachable from this host. 106.It Bq Er EHOSTUNREACH 107The remote host is not reachable from this host. 108.It Bq Er EADDRINUSE 109The address is already in use. 110.It Bq Er EFAULT 111The 112.Fa name 113argument specifies an area outside 114the process address space. 115.It Bq Er EINPROGRESS 116The socket is non-blocking 117and the connection cannot 118be completed immediately. 119It is possible to 120.Xr select 2 121for completion by selecting the socket for writing. 122.It Bq Er EINTR 123The connection attempt was interrupted by the delivery of a signal. 124The connection will be established in the background, 125as in the case of 126.Er EINPROGRESS . 127.It Bq Er EALREADY 128A previous connection attempt has not yet been completed. 129.It Bq Er EACCES 130An attempt is made to connect to a broadcast address (obtained through the 131.Dv INADDR_BROADCAST 132constant or the 133.Dv INADDR_NONE 134return value) through a socket that does not provide broadcast functionality. 135.It Bq Er EAGAIN 136An auto-assigned port number was requested but no auto-assigned ports 137are available. 138Increasing the port range specified by 139.Xr sysctl 3 140MIB variables 141.Va net.inet.ip.portrange.first 142and 143.Va net.inet.ip.portrange.last 144may alleviate the problem. 145.El 146.Pp 147The following errors are specific to connecting names in the UNIX domain. 148These errors may not apply in future versions of the UNIX IPC domain. 149.Bl -tag -width Er 150.It Bq Er ENOTDIR 151A component of the path prefix is not a directory. 152.It Bq Er ENAMETOOLONG 153A component of a pathname exceeded 255 characters, 154or an entire path name exceeded 1023 characters. 155.It Bq Er ENOENT 156The named socket does not exist. 157.It Bq Er EACCES 158Search permission is denied for a component of the path prefix. 159.It Bq Er EACCES 160Write access to the named socket is denied. 161.It Bq Er ELOOP 162Too many symbolic links were encountered in translating the pathname. 163.It Bq Er EPERM 164Write access to the named socket is denied. 165.El 166.Sh SEE ALSO 167.Xr accept 2 , 168.Xr getpeername 2 , 169.Xr getsockname 2 , 170.Xr select 2 , 171.Xr socket 2 , 172.Xr sysctl 3 , 173.Xr sysctl 8 174.Sh HISTORY 175The 176.Fn connect 177system call appeared in 178.Bx 4.2 . 179