17.7. Socket Errors A number of errno values occur only with sockets. Here is a list of socket-specific errors and a short description of each: EADDRINUSE
A requested address is already in use and cannot be reassigned. EADDRNOTAVAIL
An unavailable address was requested. EAFNOSUPPORT
An unsupported address family was specified. ECONNABORTED
The connection was aborted by software. ECONNREFUSED
The remote machine refused the connection attempt. ECONNRESET
The connection was reset by the remote end. This usually indicates that the remote machine was restarted. EDESTADDRREQ
An attempt was made to send data over a socket without providing the destination address. This can occur only for datagram sockets. EHOSTDOWN
The remote host is not on the network. EHOSTUNREAD
The remote host cannot be reached. EISCONN
A connection is already established for the socket. EMSGSIZE
The data being sent through a socket is too large to be sent as a single, atomic message. ENETDOWN
The network connection is down. ENETRESET
The network was reset, causing the connection to be dropped. ENETUNREACH
The specified network cannot be reached. ENOBUFS
Not enough buffer space is available to handle the request. ENOPROTOOPT
An attempt to set an invalid option was made. ENOTCONN
A connection must be established before the operation can succeed. ENOTSOCK
A socket-specific operation was attempted on a file descriptor that references a file other than a socket. EPFNOSUPPORT
An unsupported protocol family was specified. EPROTONOSUPPORT
A request was made for an unsupported protocol. EPROTOTYPE
An inappropriate protocol type was specified for the socket. ESOCKTNOSUPPORT
An attempt was made to create an unsupported socket type. ETIMEDOUT
The connection timed out. | 
