Programming Interfaces Guide

Connection Errors

An error is returned if the connection is unsuccessful, but an address bound by the system remains. If the connection is successful, the socket is associated with the server and data transfer can begin.

The following table lists some of the more common errors returned when a connection attempt fails.

Table 7–1 Socket Connection Errors

Socket Errors 

Error Description 

ENOBUFS

Lack of memory available to support the call. 

EPROTONOSUPPORT

Request for an unknown protocol. 

EPROTOTYPE

Request for an unsupported type of socket. 

ETIMEDOUT

No connection established in specified time. This error happens when the destination host is down or when problems in the network cause in lost transmissions. 

ECONNREFUSED

The host refused service. This error happens when a server process is not present at the requested address. 

ENETDOWN or EHOSTDOWN

These errors are caused by status information delivered by the underlying communication interface. 

ENETUNREACH or EHOSTUNREACH

These operational errors can occur because no route to the network or host exists. These errors can also occur because of status information returned by intermediate gateways or switching nodes. The status information that is returned is not always sufficient to distinguish between a network that is down and a host that is down.