I need to run a client server application in corba using c++ without using name service or without managing a shared file.
Basically want to run the server on one port and client should connect to this.
But the port will be read in client side and this needs to be communicated to server.
Is there a way to achieve this communicating the port from client to server.
Related
I created the 3 necessary containers for NuoDB using the NuoDB instructions.
My Docker environment runs on a virtual Ubuntu Linux environment (VMware).
Afterwards I tried to access the database using a console application (C# .Net Framework 4.8) and the Ado.Net technology. For this I used the Nuget "NuoDb.Data.Client" from Nuget.org.
Unfortunately the connection does not work.
If I choose port 8888, my thread disappears to infinity when I open the connection.
For this reason I tried to open the port 48004 to get to the admin container.
On this way I get an error message.
"System.IO.IOException: A connection attempt failed because the remote peer did not respond properly after a certain period of time, or the established connection was faulty because the connected host did not respond 172.18.0.4:48006, 172.18.0.4"
Interestingly, if I specify a wrong database name, it throws an error:
No suitable transaction engine found for database.
This tells me that it connects to the admin container.
Does anyone have any idea what I am doing wrong?
The connection works when I establish a connection with the tool "dbvisualizer".
This tool accesses the transaction engine directly. For this reason I have opened the port 48006 in the corresponding container.
But even with these settings it does not work with my console application.
Thanks in advance.
Port 8888 is the REST port that you would use from the administration tool such as nuocmd: it allows you to start/stop engines and perform other administrative commands. You would not use this port for SQL clients (as you discovered). The correct port to use for SQL clients is 48004.
Port 48004 allows a SQL client to connect to a "load balancer" facility that will redirect it to one of the running TEs. It's not the case that the SQL traffic is routed through this load balancer: instead, the load balancer replies to the client with the address/port of one of the TEs then the client will disconnect from the load balancer and re-connect directly to the TE at that address/port. For this reason, all the ports that TEs are listening on must also be open to the client, not just 48004.
You did suggest you opened these ports but it's not clear from your post whether you followed all the instructions on the doc page you listed. In particular, were you able to connect to the database using the nuosql command line tool as described here? I strongly recommend that you ensure that simple access like this works correctly, before you attempt to try more sophisticated client access such as using Ado.Net.
I've created a service inside minikube (expressjs API) running on my local machine,
so when I launch the service using minikube service wedeliverapi --url I can access it from my browser with localhost:port/api
But I also want to access that service from another device so I can use my API from a flutter mobile application. How can I achieve this goal?
Due to small amount of information and to clarify everything- I am posting a general Community wiki answer.
The solution to solve this problem was to use reverse proxy server. In this documentation is definiton what exactly is reverse proxy server .
A proxy server is a go‑between or intermediary server that forwards requests for content from multiple clients to different servers across the Internet. A reverse proxy server is a type of proxy server that typically sits behind the firewall in a private network and directs client requests to the appropriate backend server. A reverse proxy provides an additional level of abstraction and control to ensure the smooth flow of network traffic between clients and servers
Common uses for a reverse proxy server include:
Load balancing
Web acceleration
Security and anonymity
This is the guide where one can find basic configuration of a proxy server.
See also this article.
I'm currently struggling with docker and SSL. Let me give you an overview on what I'm trying to do.
I built a microservice-based architecture which is composed by a react web application and some "backend" services written in python and exposed with gunicorn on docker containers. I need to serve it over SSL because of Auth0 which needs the https communication. So, I built the server, bought a domain and got the SSL certificate for the domain with let's encrypt.
Now, here are the troubles, since mi services communicates to each other with a docker network, say services-network. For this reason they refer each other with the url `service:port/example.
At the moment I'm able to successfully connect to my web app with https but whenever this tries to contact the "backend" services the connection is refused because of it came from a non-secure resource (I used http://service:port/endpoint).
I tried to use the let's encrypt certificate generated for the webapp but the communication is blocked with message requests.exceptions.SSLError: HTTPSConnectionPool(host='service', port=8081): Max retries exceeded with url: /endpoint (Caused by SSLError(CertificateError("hostname 'service' doesn't match 'domain.com'",),))
I understand that a possible workaround for this error is to make the services communicate each other without using the docker network but the external one. Anyway I think that is not a good practice and that the communication among containers needs to be done through the docker network.
Finally, my question is: which is the best way to make the containers communicate through https over the docker network?
I personally like to use nginx as a reverse proxy. You would configure it normally and set it to proxy_pass <dockerIp:port>.
Many people like to use traefik.io which has many features including Let's Encrypt integration.
I am currently communicating with my Redis instance from my iOS client using a websocket. I specify the host address and the listening port and execute some Redis Commands from my IOS client directly.
The reason I am doing that because I am doing real live geolocation tracking and executing these commands from my backend which is in php will result in latency.
I am afraid that this is not the most secure way because if someone knows my host address and ports he will be able to access my Redis Instance.
My question is how can I communicate with my Redis Instance from my iOs client using a websocket but in a more secure way.
#Ahmed,
I read the answer provided by #ThatCampbellKid and the comments and understand your wish to have the iOS client communicate directly with the Redis server.
However, Redis was NOT designed for this approach. As indicated in the documentation (emphasis added):
Redis is designed to be accessed by trusted clients inside trusted environments.
The internet is not a trusted environment and the direct access allows Redis to be accessed by non-trusted clients.
The same documentation gives the following example (emphasis added):
In the common case of a single computer directly exposed to the internet, such as a virtualized Linux instance (Linode, EC2, ...), the Redis port should be firewalled to prevent access from the outside. Clients will still be able to access Redis using the loopback interface.
The correct approach would be to use a dynamic application to authenticate clients and bridge between clients and the Redis server.
You can use JWT (the nginx module suggested by #ThatCampbellKid), PHP, Ruby, node.js, Java, C or whatever you want - but you will need to use something.
I'm sorry to say this, but any other shortcut will expose your system to security risks.
EDIT:
Yes, you can still use WebSocket.
The difference is that this architecture is not secure:
Client <=(WebSockets)=> Redis
And this architecture is secure (if implemented correctly):
Client <=(WebSockets)=> Authentication Layer <=(TCP)=> Redis
There are a couple ways of doing it, depending on how your project is set up. You could add an NGINX loadbalancer in front of your php/redis containers that accepts JSON Web Tokens for authentication.
https://www.nginx.com/blog/authentication-content-based-routing-jwts-nginx-plus/
Redis has the ability to do authentication as well, but isn't considered best practices it looks like, but you can find more information about it here also:
https://redis.io/commands/auth
As you said you are already running Nginx then have a look at the Nchan websockets module
Your Nginx install can then serve websocket connections directly and it has support for several methods of client authentication as well as direct integration with redis
I have a local Ms access database in a local computer connected with internet with dynamic IP. And I have a java web application running on web server. How can I connect to Database in local pc with dynamic ip from the java application running on server
You would have to serve it from the client machine using either a local web server or a VPN tunnel.
Possibly a better idea (I mean, anything sounds better than connecting to a client-side DB, right?) would be to have the client upload the database (depending on the size) and then connecting to the server-side copy.