Cannot assign requested address using ServerSocket socketBind

Question

When I m trying to set up a socket server  I ve got an error message   Exception in thread  main  java net BindException  Cannot assign requested address  JVM Bind     at java net PlainSocketImpl socketBind Native Method      at java net PlainSocketImpl bind PlainSocketImpl java 383      at java net ServerSocket bind ServerSocket java 328      at java net ServerSocket  lt init gt  ServerSocket java 194      at java net ServerSocket  lt init gt  ServerSocket java 106      at socketyserver SocketyServer main SocketyServer java 12  Java Result  1   Whole code is simplest as it can be   public static void main String   args  throws UnknownHostException  IOException       ServerSocket serverSocket      serverSocket   new ServerSocket 9999       I m 100  sure that my ports are forwarded  Windows Firewall is off  Nothing blocks port 9999  What else can go wrong

User · Accepted Answer

As other people have pointed out  it is most likely related to another process using port 9999  On Windows  run the command   netstat -a -n   grep  LIST    And it should list anything there that s hogging the port  Of course you ll then have to go and manually kill those programs in Task Manager  If this still doesn t work  replace the line   serverSocket   new ServerSocket 9999     With   InetAddress locIP   InetAddress getByName  192 168 1 20    serverSocket   new ServerSocket 9999  0  locIP     Of course replace 192 168 1 20 with your actual IP address  or use 127 0 0 1

User · Answer

java net BindException  Cannot assign requested address   According to BindException documentation  it basically      Signals that an error occurred while attempting to bind a socket to a local address and port  Typically  the port is in use  or the requested local address could not be assigned    So try the following command   sudo lsof -i 8983   to double check if any application is using the same port and kill it   If that s not the case  make sure that your IP address to which you re trying to bind is correct  it s correctly assigned to your network interface

User · Answer

As the error states  it can t bind - which typically means it s in use by another process   From a command line run      netstat -a -n -o   Interrogate the output for port 9999 in use in the left hand column   For more information  http   www zdnetasia com see-what-process-is-using-a-tcp-port-62047950 htm

User · Answer

Just for others who may look at this answer in the hope of solving a similar problem  I got a similar message because my ip address changed   java net BindException  Cannot assign requested address  bind     at sun nio ch Net bind Native Method      at sun nio ch ServerSocketChannelImpl bind ServerSocketChannelImpl java 126      at sun nio ch ServerSocketAdaptor bind ServerSocketAdaptor java 59      at org eclipse jetty server nio SelectChannelConnector open SelectChannelConnector java 182      at org eclipse jetty server AbstractConnector doStart AbstractConnector java 311      at org eclipse jetty server nio SelectChannelConnector doStart SelectChannelConnector java 260      at org eclipse jetty util component AbstractLifeCycle start AbstractLifeCycle java 59      at org eclipse jetty server Server doStart Server java 273      at org eclipse jetty util component AbstractLifeCycle start AbstractLifeCycle java 59

User · Answer

Java documentation for java net BindExcpetion      Signals that an error occurred while attempting to bind a socket to a   local address and port  Typically  the port is in use  or the   requested local address could not be assigned    Cause   The error is due to the second condition mentioned above  When you start a server Tomcat Jetty etc  it listens to a port and bind a socket to an address and port  In Windows and Linux the hostname is resolved to IP address from  etc hosts This host to IP address mapping file can be found at C  Windows System32 Drivers etc hosts  If this mapping is changed and the host name cannot be resolved to the IP address you get the error message   Solution   Edit the hosts file and correct the mapping for hostname and IP using admin privileges   eg    127 0 0 1 localhost 192 168 52 1 localhost   Read more  java net BindException   cannot assign requested address

User · Answer

For me it was because a previous jmeter properties change was still in play  httpclient localaddress 12 34 56 78

User · Answer

In my case  delete from  etc hosts   127 0 0 1 localhost 192 168 100 20 localhost  lt  lt  lt  lt ----  delete or comment

User · Answer

The error says Cannot assign requested address  This means that you need to use the correct address for one of your network interfaces or 0 0 0 0 to accept connections from all interfaces   The other solutions about ports only work after sometimes-failing black magic  like working after some computer restarts but not others  because the port is completely irrelevant

User · Answer

The port is taken by another process  Possibly an unterminated older run of your program  Make sure your program has exited cleanly or kill it

User · Answer

I came across this error when copying configurations from one server to another   I had the old host s hostname in my   JETTY BASE  start ini jetty host property  Setting the correct jetty host property value solved the issue for me   Hope this helps someone in the future who has to work on multiple servers at once

User · Answer

if your are using server  there s  public network IP  and  internal network IP   Use the  internal network IP  in your file  etc hosts and  public network IP  in your code  if you use  public network IP  in your file  etc hosts then you will get this error

User · Answer

It may be related to a misconfiguration in your  etc hosts  In my case  it was like this  192 168 1 11 localhost instead of 127 0 0 1 localhost

User · Answer

if you happened on CentOS   You should try to this     service network restart  or  reboot your server

[java] Cannot assign requested address using ServerSocket.socketBind

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