Bind Socket Error Address Already In Use
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Address Already In Use Linux
the port number is shown free by `netstat` up vote 30 down vote favorite 8 I tried to bind my socket(server socket) at port number 8000. It worked and did the job for me. At the end of the code I close the socket as well. The very next instant I run my code again and it shows me that the address is already in use. I have address already in use socket printed the meaning of error values strerror(errno); to see if my code working properly at each point. To check if the port is free I checked it using netstat but it shows that port number 8000 is free. It has happened with me a lot of times. Every time I then wait for a few more secs and then it starts working again. I am using c language. So what is he reason for this behavior by my OS. After a few more secs I run the code and then it works. anirudh@anirudh-Aspire-5920:~/Desktop/testing$ sudo ./a.out Socket Creation: Success File open: Success Socket Bind: Address already in use Socket Listen: Address already in use ^C anirudh@anirudh-Aspire-5920:~/Desktop/testing$ sudo netstat -lntp Active Internet connections (only servers) Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name tcp 0 0 0.0.0.0:80 0.0.0.0:* LISTEN 1348/lighttpd tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN 984/sshd tcp 0 0 127.0.0.1:631 0.0.0.0:* LISTEN 1131/cupsd tcp 0 0 0.0.0.0:3306 0.0.0.0:* LISTEN 1211/mysqld tcp6 0 0 :::22 :::* LISTEN 984/sshd tcp6 0 0 ::1:631 :::* LISTEN 1131/cupsd anirudh@anirudh-Aspire-5920:~/Desktop/testing$ sudo ./a.out Socket Creation: Success File open: Success Socket Bind: Address already in use Socket Listen: Address already in use ^C anirudh@anirudh-Aspire-5920:~/Desktop/testing$ c linux sockets share|improve this questio
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just like you, helping each other. Join them; it only takes a minute: Sign up Python: Binding Socket: “Address already in use” up vote 36 down vote favorite 10 I have a question regarding client socket on http://stackoverflow.com/questions/5106674/error-address-already-in-use-while-binding-socket-with-address-but-the-port-num TCP/IP network. Let's say I use try: comSocket = socket.socket(socket.AF_INET, socket.SOCK_STREAM) comSocket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1) except socket.error, msg: sys.stderr.write("[ERROR] %s\n" % msg[1]) sys.exit(1) try: comSocket.bind(('', 5555)) comSocket.connect() except socket.error, msg: sys.stderr.write("[ERROR] %s\n" % msg[1]) sys.exit(2) The socket created will be bound to port 5555. The problem is that after ending the connection comSocket.shutdown(1) comSocket.close() Using wireshark, I see the socket closed with FIN,ACK and ACK from both sides, I can't use the port again. I get http://stackoverflow.com/questions/6380057/python-binding-socket-address-already-in-use the following error: [ERROR] Address already in use I wonder how can I clear the port right away so that next time I still can use that same port. comSocket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1) setsockopt doesn't seem to be able to resolve the problem Thank you! python sockets tcp port share|improve this question edited Dec 31 '13 at 19:49 asked Jun 17 '11 at 0:12 Tu Hoang 95372235 Why does a client need a specific port? –AJ. Jun 17 '11 at 0:17 Because I have to put that into a production server, and in that server, all outgoing connections are blocked. I need to specify a specific port to the socket so that they can set up a rule on the firewalls that allows the connection to go through. –Tu Hoang Jun 17 '11 at 0:46 I suggest you copy & paste the actual code. What you wrote above has an obvious error that would prevent you from seeing the behavior you claim to have seen. This leaves readers with no idea what else you have neglected to tell us that might be causing your problem. –ʇsәɹoɈ Jun 17 '11 at 1:01 2 Your network administrators should understand that outbound traffic can be controlled by destination port. –AJ. Jun 17 '11 at 1:02 4 t
and both ends must ACK (acknowledge) each other's FIN packets. The FIN packets are initiated by the application performing a close(), a shutdown(), or an exit(). The ACKs are handled by the kernel after http://hea-www.harvard.edu/~fine/Tech/addrinuse.html the close() has completed. Because of this, it is possible for the process to complete before the kernel has released the associated network resource, and this port cannot be bound to another process until the kernel has decided that it is done. Figure 1 Figure 1 shows all of the possible states that can occur during a normal closure, depending on the order in which things happen. Note that if you initiate closure, there is address already a TIME_WAIT state that is absent from the other side. This TIME_WAIT is necessary in case the ACK you sent wasn't received, or in case spurious packets show up for other reasons. I'm really not sure why this state isn't necessary on the other side, when the remote end initiates closure, but this is definitely the case. TIME_WAIT is the state that typically ties up the port for several minutes after the process has completed. address already in The length of the associated timeout varies on different operating systems, and may be dynamic on some operating systems, however typical values are in the range of one to four minutes. If both ends send a FIN before either end receives it, both ends will have to go through TIME_WAIT. Normal Closure of Listen Sockets A socket which is listening for connections can be closed immediately if there are no connections pending, and the state proceeds directly to CLOSED. If connections are pending however, FIN_WAIT_1 is entered, and a TIME_WAIT is inevitable. Note that it is impossible to completely guarantee a clean closure here. While you can check the connections using a select() call before closure, a tiny but real possibility exists that a connection could arrive after the select() but before the close(). Abnormal Closure If the remote application dies unexpectedly while the connection is established, the local end will have to initiate closure. In this case TIME_WAIT is unavoidable. If the remote end disappears due to a network failure, or the remote machine reboots (both are rare), the local port will be tied up until each state times out. Worse, some older operating systems do not implement a timeout for FIN_WAIT_2, and it is possible to get stuck there forever, in which case restarting your server could require a reboot. If the