I want to check if a server or ip has ftp service running before connect to it. I have the next code, however if the ftp service is not active I get: "Error: failed to connect to localhost...NNREFUSED (connection refused)"
I want to capture this error to show message if service is offline or continue if is online.
ftpClient.connect(localhost, 21);
Boolean temp = FTPReply.isPositiveCompletion(ftpClient.getReplyCode());
Log.d(TAG,"respuesta server: " + Boolean.toString(temp));
The main problem is that in line 1, logcat shows the error and the lines after it are not executed.
I don't know if with FTPClient is possible, if not, something similar to make a "telnet localhost 21" manually for example.
Note: the error is not a exception.
I want to check if a server or IP has FTP service running before [trying to] connect to it
No you don't. The best way to tell whether it's running is to try to connect to it. If you get a connect exception, it isn't running. No other scheme you can devise will work as well.
Related
I'm trying to write a program in the android studio. I'm shooting the database with the webservice rest api. But I get this error, I couldn't log in.
enter image description here
enter image description here
on your okhttp client builder the connection timeout is 3 second, also make sure you are adding internet permission to the manifest file,
cleartextTrafficPermitted=false on manifest file.
if you are running the web service from the local servers like wamp or xxamp make sure to add all configurations required check this link
When trying to upload file to FTP with java program:
public void upload(String localFile,String remoteFile) throws Exception{
ftp = new FTPClient();
ftp.setControlKeepAliveTimeout(300);
ftp.connect(host,21);
ftp.enterLocalPassiveMode();
ftp.setUseEPSVwithIPv4(false);
ftp.login(user,password);
ftp.setFileType(FTPClient.BINARY_FILE_TYPE);
FileInputStream in = null;
in = new FileInputStream(localFile);
ftp.storeFile(remoteFile,in);
in.close();
ftp.disconnect();
}
I'm getting:
java.net.ConnectException: Connection refused
at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:381)
at java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:243)
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:230)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:377)
at java.net.Socket.connect(Socket.java:539)
at org.apache.commons.net.SocketClient._connect(SocketClient.java:243)
at org.apache.commons.net.SocketClient.connect(SocketClient.java:202)
When I try to upload the same file with command line (from linux), I'm able to do it only when using EPSV:
llnx:~ ftp anonymous#9.20.1.116
Connected to 9.20.1.116.
220 Microsoft FTP Service
331 Anonymous access allowed, send identity (e-mail name) as password.
Password:
230 User logged in.
Remote system type is Windows_NT.
ftp> epsv
EPSV/EPRT on IPv4 off.
ftp> put /tmp/file1.xml /dir_1/file1.xml
local: /tmp/file1.xml remote: /dir_1/file1.xml
227 Entering Passive Mode (10,40,1,149,233,168).
125 Data connection already open; Transfer starting.
100% |*************************************| 117 KB 28.66 MB/s --:-- ETA
226 Transfer complete.
120032 bytes sent in 00:00 (7.96 MB/s)
So, Why does my java code getting Connection refused?
Maybe I'm not using the enterLocalPassiveMode() or setUseEPSVwithIPv4() method the right way?
*** I think the answer is how to run the EPSV command from Java program.
Thank you all.
Eithan.
This is purely a guess but java.net.ConnectException: Connection refused normally happens when there is nothing listening on the target host/port. You don't specify a port in the CLI example so maybe that is the problem. Try changing ftp.connect(host,21); to ftp.connect(host); to use the default. Also confirm the the hostnames are exactly the same.
This assumes that the error is on the call to connect(). You haven't provided a big enough stack trace to indicate either way.
Connection refused means that your TCP connection request has reached the remote server (or more correctly >>a<< remote server) but the server is not expecting / listening for an incoming connection. So it "refuses" it.
Here are the things to check:
Check that you have the correct remote hostname or IP address for the FTP server.
Check that you are using the correct port for the FTP server. Port 21 is the default, but it is possible that the server is on a non-standard port.
Check that the FTP server is actually running.
It is also possible that the problem is due to a firewall doing something deliberately confusing. But that is unlikely for a publicly routable FTP server.
Maybe I'm not using the enterLocalPassiveMode() or setUseEPSVwithIPv4() method the right way?
That can't be the problem. The stacktrace shows that your application failed while trying to establish the initial connection to the server. You haven't gotten to the point where the you can make those calls.
I am developing a mini project using Java and Oracle XE database.
I was able to connect to database, insert, update and run all other queries from my personal computer, but when I tried to run the same program on my college computer (which is networked) it did not run and gave me the following exception message:
io error:network adapter could not establish the connection
I tried researching the error message on the internet and found that it must be a firewall or port number problem, but I am unable to sort it. How can I fix this error?
Here is the connection code that I used:
public void connect()
{
try
{
Class.forName("oracle.jdbc.driver.OracleDriver");
conn=DriverManager.getConnection("jdbc:oracle:thin:#localhost:1521:XE","system","system");
}
catch(Exception e)
{
JOptionPane.showMessageDialog(this, e.getMessage());
}
}
SimpleDateFormat sd=new SimpleDateFormat("dd-MM-yy");
DefaultTableModel table_allrec;
PreparedStatement pstmt,pstmt1;
Connection conn;
ResultSet rs,rs1;
This error is most likely caused by one of these factors:
You are using the wrong URL
The wrong port number or IP address (or DNS host name) was used
The listener is not configured properly
The listener process (service) is not running. You can re-start it with the "lsnrctl start" command or on Windows by starting the listener service.
Please make sure, you are entering correct username, password, hostname, PORT, SID while creating connection in SQL Developer
On the machine where DB is installed,
go to this folder C:\app{{Username_machine}}\product\11.2.0\dbhome_1\NETWORK\ADMIN
P.S. : {{Username_machine}} : This is will differ from machine to machine
Open 2 files inside this listener.ora AND tnsnames.ora
Check hostname, PORT, SID mentioned in the files MUST match with the one you are trying to use in STEP 1.
If any of the value doesn't match, Use the values present in the 2 Files for creating connection in SQL Developer
Try to connect with updated values in case mismatch of values were found
If you are still not able to connect
press windows + R, and type services.msc -- this is will open Services running on your machine
restart all the services that are starting with oracle
Try to reconnect again on SQL Developer
If it fails again,
Open CMD in administrative mode,
Check if Your TNS Listener is up by typing the following command
lsnrctl status
The above command will give error if the Listener is not up
Start the Listener, by typing the following command,
lsnrctl start
In case you are having problems in starting your listener then try starting “OracleOraDb11g_home1TNSListener” windows service. For that open your Run Command and write services.msc this will open your service panel. Here search for the same and right click to start it.
Doing the above steps, will resolve your Problem. Thanks !
I'm trying to add the Derby included with WebLogic as a data source. I'm running WebLogic 10.3.5. I didn't see a Derby flag in the setDomainEnv.cmd, so I added the client driver to the CLASSPATH:
set CLASSPATH=%PRE_CLASSPATH%;%WEBLOGIC_CLASSPATH%;%POST_CLASSPATH%;%WLP_POST_CLASSPATH%;%WL_HOME%\common\derby\lib\derbyclient.jar
in setDomainEnv.cmd. Now when I try to activate my data source in WebLogic I get:
An error occurred during activation of changes, please see the log for
details. Message icon - Error weblogic.application.ModuleException:
Message icon - Error java.net.ConnectException : Error connecting to
server localhost on port 1527 with message Connection refused:
connect.
What else do I need to do to get this to work?
I believe your local derby is not up yet. To check this, issue:
netstat -an | findstr 1527.
See if it returns anything. If nothing is returned, try to start the Derby Network Service manually. Go to <WLS_HOME>\common\derby\bin and click the startNetworkServer.cmd.
Double check with netstat again. If it's there, you can try to add to the datasource.
Note: this only covers manually start the Derby network service (not automatially start it upon weblogic start, which a bit tricky).
Either whatever is supposed to be running on that port isn't running or there is a firewall issue.
i have written a program to connect to ssh server using JSCH lib, the program runs well.
in the catch block i have used
catch(JSchException ee)
{
....
}
when error occurs i get these messages,
com.jcraft.jsch.JSchException: java.net.NoRouteToHostException: No route to host
com.jcraft.jsch.JSchException: Auth fail
com.jcraft.jsch.JSchException: timeout: socket is not established
now i need to display the error message in a dialog box. for each type of error i have to display different output. plz guide me how to process these exceptions and to differentiate them..
Your server seems to be unreachable: "No route to host" so your client cannot connect to it "Auth fail" and the socket reaches its timeout.
Try to ping the server to see its response. Make sure you give the same ip address you use in the program. If you directly provide the server name, check your host file /etc/hosts on Linux or %SystemRoot%\system32\drivers\etc\hosts.
ADD below nuget packages to your solution
DiffieHellman
Org.Mentalis.Security