Re: [lwip-users] TCP FIN question

[Kieran Mansley]

On Thu, 2006-09-14 at 15:10 +0530, Yadnesh Phadke wrote:

> Why is this the case when, TCP documentation says that the client is
> expected receive FIN from the server?  Is the client always expected
> to send RST to close connection from it's side?  And FIN is used only
> for closing connection initiated by the server? 

TCP connections are duplex, i.e. data can go in both directions, and
each direction is closed independently.  The FIN means "I've finished
sending data in this direction", not "close the connection in both
directions".  The server will send a FIN when it has finished sending
data (i.e. when the server application calls close()).

If you really really must close a connection now and not care about any
data getting lost, then you can use a RST, but it's not meant for normal
closing of connections.

Kieran