ConnectException: operation timed out
I have the following class that opens a socket connection to query a WHOIS server. Unfortunately, every time I run it (e.g. java WHOIS google.com) it always throws the exception:
Contacting the WHOIS server for 'google.com' at whois.internic.net:43
Exception in thread "main" java.net.ConnectException: Operation timed out
at java.net.PlainSocketImpl.socketConnect(Native Method)
at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:333)
at java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:195)
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:182)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:432)
at java.net.Socket.connect(Socket.java:529)
at java.net.Socket.connect(Socket.java:478)
at java.net.Socket.<init>(Socket.java:375)
at java.net.Socket.<init>(Socket.java:189)
at WHOIS.performWhoisQuery(WHOIS.java:11)
at WHOIS.main(WHOIS.java:28)
The problem seems connection timeout and i tried setting the timeout to a longer value (e.g. 5000) and it didn't work. Does it have to do with proxy and/or firewall? I got stuck whole day on it.
public class WHOIS {
public static void performWhoisQuery(String host, int port, String query) throws Exception {
System.out.println(" Contacting the WHOIS server for '" + query + "' at " + host + ":" + port);
Socket socket = new Socket(host, port);
InputStreamReader isr = new InputStreamReader(socket.getInputStream());
BufferedReader br = new BufferedReader(isr);
PrintWriter out = new PrintWriter(socket.getOutputStream(), true);
out.println(query);
String 开发者_高级运维aLine = "";
while ((aLine = br.readLine()) != null) {
System.out.println(aLine);
}
}
public static void main(String[] args) throws Exception {
String domainNameToCheck = args[0];
performWhoisQuery("whois.internic.net", 43, domainNameToCheck);
}
}
One easy way to check whether it's a firewall issue is by using telnet
to connect to the target host/port from the same computer.
For example, on my Linux box:
aix@aix:~$ telnet whois.internic.net 43 Trying 199.7.57.74... Connected to whois.internic.net. Escape character is '^]'.
If you're able to connect, then the problem is with your Java program. Otherwise the problem is somewhere else (firewall etc).
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