Client-Server Socket Connection Question

[sumitv]

Hi,

I have written a server code that accepts TCP/IP socket connections from client. The server code has listen() system call with its last argument(backlog) set to 1. This way there can be maximum of 1 pending connections. Also server accepts incoming client socket connections from any IP address.

But I have observed that, even after one successful client connection, if I try to connect more than 1 client, all the clients connect successfully to the server. My understanding is that unless server calls accept() system call, it does not establish socket connection with client. But still client is getting connected successfully.

Is underlying linux TCP/IP stack layer handle this?
Please explain this behavior.

Regards,
Sumit

[Rubberman]

The backlog is only relevant to SIMULTANEOUS connection requests. It has NOTHING to do with how many actual connections the server can handle. This is a common misconception amongst newbie socket programmers.

[sumitv]

Thanks. It is clear now.

Regards,
Sumit

[Rubberman]

So, if you want to limit the server to a single connection, then you need to monitor the connection in the server, and reject any connection requests until the current client has disconnected, or the socket has timed out if you wish to do that - a good idea in order to keep one client from "hogging" the server's resources.