Port number of socket returned by accept() Post: 302336286

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Special Forums IP Networking Port number of socket returned by accept() Post 302336286 by idelovski on Tuesday 21st of July 2009 06:31:23 PM

07-21-2009

Registered User

Port number of socket returned by accept()

Hi,

I typed a few tcp/ip client/server examples from a book and it works - sort of - but I noticed something strange. When I run my server I set it to use port 3001 and the client uses the same port to connect to server. They succeed, but the server prints something that doesn't really make much sense: it prints that the client uses port 30152. Next time I run it is 30153 and next time is 30154 and so on.

Here is the code of the server, accept() call and printf() call.

Code:

      struct sockaddr_in  clntAddr, testAddr;
      socklen_t           clntAddrLen = sizeof (struct sockaddr_in);

      int                 clntSock = accept (servSock, (struct sockaddr *)&clntAddr, &clntAddrLen);

      if (clntSock < 0)
         DieWithSystemMessage ("accept() failed");

      char  clntName[INET_ADDRSTRLEN];  // str to contain client address
      
      if (inet_ntop(AF_INET, &clntAddr.sin_addr.s_addr, clntName, INET_ADDRSTRLEN))
         printf ("Handling client %s/%hu\n", clntName, ntohs(clntAddr.sin_port));

I am on Mac (10.5) and the book is TCP/IP Sockets in C. (Full source code link - TCPEchoClient4.c & TCPEchoServer4.c + DieWithMessage.c & Practical.h)

idelovski

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aseqnet

aseqnet(1)						      General Commands Manual							aseqnet(1)

NAME

       aseqnet - ALSA sequencer connectors over network

SYNOPSIS

       aseqnet [remotehost]

DESCRIPTION

       aseqnet	is an ALSA sequencer client which sends and receives event packets over network.  Suppose two hosts connected by network, hostA as
       a server and hostB as a client.	The ALSA sequencer system must be running on both hosts.  For creating the server port, run the  following
       on hostA:

	   hostA% aseqnet
	   sequencer opened: 128:0

       Then a user client 128 with port 0 was opened on hostA.	(The client number may vary.)  For creating the (network-)client port, run aseqnet
       with the hostname of the server:

	   hostB% aseqnet hostA
	   sequencer opened: 132:0

       Now all events sent to hostA:128:0 are transferred to hostB:132:0, and vice versa.

       The ports created by aseqnet can be connected arbitrary to other sequencer ports via aconnect(1).  For example, to connect hostB:132:0 to a
       MIDI output device 65:0:

	   hostB% aconnect 132:0 65:0

       Then events to hostA:128:0 will be delivered to hostB:65:0.  The following command plays MIDI on hostB.

	   hostA% pmidi -p 128:0 foo.mid

       The  multiple  clients  may  exist simultaneously.  If hostC is connected as a client to hostA, events from from hostA are sent to all con-
       nected network clients, i.e. hostB and hostC.  However, only one connection is allowed from a client to a server.

       To disconnect network, stop all clients before server by ctrl-C or sending signal to them.  The server will automatically quit.

OPTIONS

       -p port
	      Specify the TCP port number or TCP service name.

       -s addr
	      Subscribe to the given address for read automatically.

       -d addr
	      Subscribe to the given address for write automatically.

       -v     Verbose mode.

SEE ALSO

       aconnect(1), pmidi(1)

AUTHOR

       Takashi Iwai <tiwai@suse.de>.

								  January 1, 2000							aseqnet(1)