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How do I use port forwarding to connect to an Oracle database using netsh?

I have a machine(A) that has access to the host running the Oracle listener. I can connect to it fine using SQL Developer.
I have another machine(B) that I would also like to make a connection to the same database but its doesn't have direct access to the host running the listener. However, it does have access to machine (A).
I would like to forward a port on machine A to the Oracle listener host which is listening on port 1521.
Then I should be able to make a database connection from machine B to machine A and then forward a port to the host that has the Oracle listener. Sort of a man in the middle.
However, I'm running into issues. I can't even connect to the Oracle database from machine B using the forwarded port. I have experience using ssh tunnels to do the same thing. In this case, I'm not using ssh and I don't understand why this will not work.
Below is the procedure I'm going through:
Log into machine B - Oracle client is installed. SQL Developer is installed.
Open SQL Developer - Select TNS connection. Enter in credentials. Connection Successful
TNS Names entry:
CRYSTAL=(DESCRIPTION=(ADDRESS_LIST=(LOAD_BALANCE=yes)(FAILOVER=ON)(ADDRESS=(PROTOCOL=TCP)(HOST=testhost.com)(PORT=1521)))(CONNECT_DATA=(service_name=svc1)))
Now setup forwarding:
C:\Windows\system32>netsh interface portproxy add v4tov4 listenaddress=127.0.0.1
listenport=1521 connectaddress=testhost.com connectport=1521
protocol=tcp
If I telnet localhost 1521 , it is able to make a connection.
As a simple test, I make sure I can connect on Machine B using SQL Developer. But this time, I set the connection type to advanced so I can enter the jdbc url.Note, I use 127.0.01 instead of testhost.com because it will be forwarded to testhost.com
jdbc:oracle:thin:#(DESCRIPTION=(ADDRESS_LIST=(LOAD_BALANCE=yes)(FAILOVER=ON)(ADDRESS=(PROTOCOL=TCP)(HOST=127.0.0.1)(PORT=1521)))(CONNECT_DATA=(service_name=svc1)))
This connection fails with "ORA-12516, TNS: listener could not find available handler with matching protocol stack"
I've checked for firewall issues and made sure port 1521 is open.
Any ideas what I might be missing or has anyone else had success forwarding a port to an Oracle listener?

Thanks to the comment from psaraj12, I knew my approach should work. The problem I was having was due to the host name I was given to connect to the database. It works fine if you enter it into SQL Developer as is. However, when I used it in the port forwarding, I could not connect to the database using SQL Developer using the host name localhost. The host name I was given had "scan" in the name. I think this is a Virtual IP. We use Oracle RAC which is a clustering technology. So I suspected to that the VIP selected a node on the cluster and the forwarder could not handle it. So this is how I solved the problem:
Installed Wireshark.
Start recording packets.
Used SQL Developer To Connect with the VIP - Success
In Wireshark, find the TCP Stream that contains something unique about the connection. In this case, the Oracle service name. You should see the IP of the VIP. Something like:
.........6.,.A ...O........:..............................(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=11.3.68.171)(PORT=1521))(CONNECT_DATA=(CID=(PROGRAM=SQL Developer)(HOST=jdbc)(USER=adpc))(SERVICE_NAME=svc1)(CID=(PROGRAM=SQL Developer)(HOST=jdbc)(USER=adpc)))).................6.,.A ...O........:..............................(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=11.3.68.171)(PORT=1521))(CONNECT_DATA=(CID=(PROGRAM=SQL Developer)(HOST=jdbc)(USER=adpc))(SERVICE_NAME=svc1)(CID=(PROGRAM=SQL Developer)(HOST=jdbc)(USER=adpc)))). .......6.A ........ ..........................
Now, go back to the packet and find out what the "real" address is. Here is an example:
Wire shark packet information. This is the destination IP where Oracle listener is.
Now use this to forward the port.
netsh interface portproxy add v4tov4 listenport=1521 connect address=11.3.68.135 connectport=1521 protocol=tcp
Now, when you log in using SQL Developer Basic Connection Type, you can use localhost instead of the VIP and you should be able to connect.
Now, go to another machine that has access to the machine you just set up and you should be able to connect to the database from there as well using the IP of the machine where you have port forwarding setup.

The same forward connection is working fine in both basic and advanced connection in SQL developer in my machine.
The only difference is machine A,B and Database are in the same network in my case where B can directly connect to the database also
Steps
1)You have to set up forwarding in machine A with machine A ip address as the listen address
2) Use the machine A ipaddress in TNS to connect to Database in machine B
If still, you are facing problems then you can try enabling log and trace files to identify the issue as mentioned in these articles
Oracle Database 10g Debugging Connection problems 1
Oracle Database 10g Debugging Connection problems 2

How to connect to SQL Server 2017 on a network computer (That is listening to a local port)

I would like to connect to a database that runs locally on one of our network computers here at work. I can connect to it just fine with the application that I developed that uses Java's sql driver manager. Now I would like to distribute it to the different computers on the network. To do this, I need a url that will point to the database through the network. The database is listening to port 1434. (Static URL string is "//localhost:1434")
MatsysUI.setConnection(DriverManager.getConnection("jdbc:sqlserver:" + MatsysIO.getStaticURL(), txtUser.getText(), txtPassword.getText()));
Problem is, I don't know where to start to find that, and I would like to avoid using an internet connection to connect to this database. Is there a way to route the connection to the network computer, then to its local port?

There are several possible answers to this.
I just want to restate your situation to make sure I understand:
You have an application, written in Java, which requires access to a SQL Server database.
You want to distribute multiple copies of that application to different client machines.
The client machines and the database server are all on a local network.
SQL Server is listening on port 1434
You need to construct the JDBC connection string on the client machines to access SQL Server.
You give the current connection string as //localhost:1434; in that scheme, localhost is the hostname. You can replace this with the fully qualified domain name of the SQL Server machine (this is almost certainly the simplest option). Using the FQDN allows you to replace the machine, or load balance it, etc. without worrying about the connections - but if the machine name ever changes, all your connections break!
You can also connect by IP address - this allows you to change the machine name, but obviously means the IP address can never change. In most circumstances, that's a bad thing.
Your final option is to look for alL SQL Servers on your network, and show them in a drop down for your user (your code suggests you're using username and password inputs). This means you don't have to distribute a new properties file if you want to change your server details.

how to specify host using ip address instead of name to connect to postgres database using netbeans in a java project?

i want to add database to my netbeans java project using ip address.
my question is that when i specify hostname by name that is "localhost" followed my correct details in the new connection wizard in netbeans connection establishes succesfully. this is as shown below.
but when i specify host by specifying ip address of my own computer that is localhost connection doesn't get established. same is shown below
well my motive is not to put ip of localhost but of another pc for remote database sharing over internet. but i think the problem lies in the method of specifying host using ip. if i get it right database sharing might work between different hosts as well.
also any other methods of sharing postgres database over the internet are also welcome.
i am a newbie in java as well as netbeans so any help is appreciated.

Your sense of thinking that localhost is your IP-Address is itself wrong!You need to have a loop-back address which will direct your operations to itself and not as the case of your IP-Address shown in ipconfig command.
You need to specify this 127.0.0.1 as the IP-Address.
127.0.0.1 is the most-commonly used IPv4 loopback address.
Try this :- jdbc:postgresql://127.0.0.1:5432/nic_project_db
localhost means this computer. It is a hostname that the computer's
software and users may employ to access the computer's own network
services via its loopback network interface. Using the loopback
interface bypasses local network interface hardware. // Taken from Wikipedia.

For future reference to anyone that might have same question here is solution:
In the postgresql database folder open up the postgresql.conf file. Add the following line:
listen_addresses = '*'
Then open up the pg_hba.conf file and add the following line:
host all all 0.0.0.0/0 md5

IO Error: The Network Adapter could not establish the connection

I am new to Oracle, and am trying to run a simple example code with Java, but am getting this error when executing the code.. I am able to start up the listener via CMD and am also able to run SQL Plus. Can anyone give me a hand and tell me what I might be doing wrong?
Update:
I am using JDBC.
Database is local, and I actually had it working but it stopped working just today. I'm not really sure why though. Would you mind giving me some procedures to follow by since I don't know much.

Either:
The database isn't running
You got the URL wrong
There is a firewall in the way.
(This strange error message is produced by Oracle's JDBC driver when it can't connect to the database server. 'Network adapter' appears to refer to some component of their code, which isn't very useful. Real network adapters (NICs) don't establish connections at all: TCP protocol stacks do that. It would have been a lot more useful if they had just let the original ConnectException be thrown, or at least used its error message and let it appear in the stack trace.)

I had the same problem, and this is how I fixed it.
I was using the wrong port for my connection.
private final String DB_URL = "jdbc:oracle:thin:#localhost:1521:orcll"; // 1521 my wrong port
go to your localhost
(my localhost address) : https://localhost:1158/em
login
user name
password
connect as --> normal
Below 'General' click on LISTENER_localhost
look at you port number
Net Address (ADDRESS=(PROTOCOL=TCP)(HOST=localhost)(PORT=1522))
Connect to port 1522
Edit you connection
change port 1521 to 1522.
done

Another thing you might want to check that the listener.ora file matches the way you are trying to connect to the DB. If you were connecting via a localhost reference and your listener.ora file got changed from:
HOST = localhost
to
HOST = 192.168.XX.XX
then this can cause the error that you had unless you update your hosts file to accommodate for this. Someone might have made this change to allow for remote connections to the DB from other machines.

I figured out that in my case, my database was in different subnet than the subnet from where i was trying to access the db.

I had this error when i renamed the pc in the windows-properties. The pc-name must be updated in the listener.ora-file

Most probably you have listener configured wrongly, the hostname you specify in connection string must be the same as in the listener.
First check the Firewall and network related issues.
Check if Oracle Listener service is available and running. If not you may use Oracle Net Configuration Assistant tool to add and register new listener.
If the above steps are ok then you need to configure Oracle Listener appropriately. You may use Oracle Net Manager tool or edit “%ORACLE_HOME%\network\admin\listener.ora” file manually.
There are 2 options that need to be considered carefully:
Listening Locations associated with the Listener – Hostname(IP) and Port in Listening Location must exactly match the ones used in the connection string.
For example, if you use 192.168.74.139 as target hostname, then there must be Listening Location registered with the same IP address.
Also make sure the you use the same SID as indicated in Database Service associated with the Listener.
https://adhoctuts.com/fix-oracle-io-error-the-network-adapter-could-not-establish-the-connection-error/

IO Error: The Network Adapter could not establish the connection (CONNECTION_ID=iKQM6lBbSLiArrYuDqud8A==)
if you are facing this issue
1- make sure you have downloaded oracle databases like oracle 11g,19c, 21c, or any latest databases.
2- search for services in your computer or type win+r then services.mis then search for oracleservice you will find orcl or xe or any other sid like oracleserviceorcl;
after that you can test your connection using sql developer, sql plus or cmd

To resolve the Network Adapter Error I had to remove the - in the name of the computer name.

In my case, I needed to specify a viahost and viauser. Worth trying if you're in a complex system. :)

For me the basic oracle only was not installed. Please ensure you have oracle installed and then try checking host and port.

I was having issues with this as well. I was using the jdbc connection string to connect to the database. The hostname was incorrectly configured in the string. I am using Mac, and the same string was being used on Windows machines without an issue. On my connection string, I had to make sure that I had the full url with the appending "organizationname.com" to the end of the hostname.
Hope this helps.

Just try to re-create connection. In my situation one of jdbc connection stopped working for no reason. From console sqlplus was working ok.
It took me 2 hours to realize that If i create the same connection - it works.

Whats my hostname on my local MySQL server?

I just set up a MySQL server on my PC for testing Java with JDBC.
At the moment "localhost" works perfectly as hostname for my applications, when running them on the same system.
However what would be the hostname for my MySQL server for applications that are running on different computers? Something like "my_ip:port" would work? I was thinking of writing an applet, which I could upload on a web server and try to connect to my database here. Is it possible to achieve that?

Something like "my_ip:port" would work?
If the MySQL instance has bound to your public interface, and if your firewall allows it, yes. If you connect to the 'net via a router that does NAT (for instance, a combined DSL modem and wireless router allowing you to connect multiple computers), you'll have to set up forwarding rules in the router to tell it which of the local machines to forward requests to.
You don't have to use an IP address. Your machine will also probably have a host name of some kind (either one you've assigned or, if you connect through an ISP, more likely one they've assigned). That would work too.
I was thinking of writing an applet, which I could upload on a web server and try to connect to my database here. Is it possible to achieve that?
With a signed Java applet, yes; otherwise, no. That's because the security sandbox that Java applets run in doesn't let them access servers other than the one they were loaded from (the web server).
A much better approach is to have your client-side code (Java applet, or just DHTML+Ajax stuff) talk to server-side code on the web server, which in turn talks to your DB. That way, the DB is never directly exposed to the outside world, and you don't have to do things like signed applets.

You can always use the ip address of the server running mysql as the hostname or its fully qualified domain name.

That should work, but you also should consider port-forwarding through your firewall.
Go here to get your IP: http://www.whatsmyip.org/
The port is the port mysql is setup on.