We need to set up an ejtserver instance inside an OpenShift cloud and expose it to an external network.
I have been told that a binary protocol is a big no-no in that situation, as it requires an extra, manually-set-up egress route (lots of extra work by external team), and takes up a limited resource (port number - ports numbers for binary egress routes need to be unique).
No such limitations exist for HTTP(S) traffic because the routers know enough about the protocol to differentiate connections through host name, which is an unlimited resource.
So I hope I can make the connection from install4j-maven-plugin to the ejtserver instance through HTTP(S); is this possible?
As of 1.13.1, this is not possible, please contact support#ej-technologies.com for alternative arrangements with build-only license keys.
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I am currently working on a multiplayer game that is meant to handle 20-50 player connections to a single game instance.
My current client connection model:
Client requests connection from server rest endpoint
Server creates 2 new sockets bound to random ports (1 tcp and 1 udp)
Client gets response and connects
I don't see anything glaringly wrong with this, but I am now questioning whether this is the general way that game server connections are done.
To explain further, I am in the process of learning how to use Kubernetes and Agones to deploy and manage app/game instances by wrapping them in Kubernetes pods. I am mostly working off of information found in the official guides (https://agones.dev/site/docs/getting-started/create-gameserver/) and associated github examples (https://github.com/googleforgames/agones/blob/release-1.15.0/examples).
For Agones, my understanding is that client connections are made via the port specified in "hostPort" in the "GameServer" yaml. I have previously deployed some instances with plain Kubernetes, using the "hostNetwork=true" option, which enables my above network model to work by allowing the game instance to bind directly to host ports and be exposed to the outside network. With Agones though, it seems that using this option is, at the very least, not encouraged (https://github.com/googleforgames/agones/issues/1389).
I'm certainly not an expert on networking, so please forgive my ignorance, but how are the client connections meant to be handled here if I'm only exposing one port? Is all the traffic multiplexed, or can I directly pass off connections somehow to other sockets/ports and have them automatically be exposed to the outside network?
Is all the traffic multiplexed, or can I directly pass off connections somehow to other sockets/ports and have them automatically be exposed to the outside network?
I would multiplex the traffic. It sounds like right now you are using the incoming port to determine "who is who". But you could also include that information in the packet flow to a shared port instead.
I am working on an embedded software product that runs on an Ubuntu edge computer with multiple network ports.
The software allows the user to change the IP address of the ports via a locally hosted web interface.
In the scenario that a customer changed an IP on one of our devices, but then forgets their setting I am looking for an easy strategy to walk them through detecting the IP.
Ideally this tool would be usable by non-sophisticated customers (we don’t want to walk them through using Wireshark or command line tools).
Is there a service we can setup on our machine that will broadcast its identity across subnets using another protocol like UDP or EtherNet/IP? Then a simple tool the client could install on their computer to ‘scan’ for our devices?
The edge computers also have USB ports if it is easier to broadcast an identify there.
Changing a local IP address to something invalid (=not compatible with its local subnet) generally disables all L3 communication. Limited broadcasts (to 255.255.255.255) still work, but answering to them by unicast most likely won't. The same goes for multicasting - but you could use that for discovery both ways.
Also, the common link-level discovery protocols (like LLDP or CDP) still work since they don't rely on IP.
However, all that is limited to the connected L2 segment at most. Discovery across subnets isn't possible without some kind of infrastructure (discovery sensors, central server, multicast routing, ...). A reasonable way would be dynamic DNS but then again, that requires IP to work.
I think you'd need to take a step back and reevaluate your design. One way would be to verify a user's reconfiguration before it becomes permanent. For instance, you could have a user change the IP setup and then forward the session to the new IP address. If the session isn't continued within five minutes or so on the new address, it reverses to the previous config.
Additionally, some kind of out-of-band management could be useful.
I am looking for GCP networking best practice, where I can allow connection of auto-scaled instances to Postgresql server installed on separate instance.
So far I tried whitelisting load-balancer IP within firewall and postgresql config file, but failed.
Any help or pointer is highly appreciated.
The load-balancer doesn't process information by itself, it just redirects Frontend addresse(s) and manage the requests with Instance Groups.
That instance group should manage the HTTP requests and connect with the database instance.
The load-balancer is used to dynamically distribute (or even create additional instances) to handle the requests over the same Frontend address.
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So first you should make it work with a regular instance, configure it and save the instance template. Then you can proceed with creating an instance group that can be managed by a load-balancer.
EDIT - Extended the answer from my comment
"I don't think your problem is related to Google cloud platform now. If you have a known IP address for the PostgreSQL server (connect using an internal network IP address so it doesn't change), then make sure your auto-balanced instances are in the same internal network, use db's internal IP and connect to it."
I'm implementing the PASV mode in a FTP server, and I send to the client the IP address and port of the data end point. This is stupid because the IP is actually where the client is already connecting, so there ire two options:
How could I get the public IP
address from a given instance? Not
the VIP, but the public one.
How could I get the original target
IP address that the user used from
a Socket object? Considering routers and load balancers in the middle :P
An answer to any of this questions would do, although there is another way that could work... may I get the public IP address doing a DNS look up of myapp.cloudapp.net?
A fourth option would be use the Azure Management API library... but, too much trouble :P.
Cheers.
Not sure if you ever figured this out, but here's my take on it. The individual role instances are all behind the Windows Azure load balancer and have no idea what the original, outward-facing IP address is. Also, there's no Management API call that returns IP address - Get Deployment returns the URL but not the IP address. I think the only option is going to be a dns lookup.
Having said that: I don't think you can host a passive ftp server in your role instance (at least not elegantly). You may open up to 25 input endpoints on your role (up from 5 - see my recent blog post about this update), but there's manual work involved in the configuration. I don't know if your ftp application lets you limit your port range to such a small number of ports. Also:
You'd have to define each port as its own input endpoint (this is the manual labor part I mentioned) - input endpoints don't allow a port range to be specified, unlike the internal endpoints.
You'd have to specify the port number that's used internally, and the port numbers would need to be sequential
One last thing on ftp: you should be able to host an sftp server with no trouble, since all traffic comes through one port.
The hack that I'm contemplating right now is to retrieve http://www.icanhazip.com/. It isn't elegant and is subject to the availability of that service, but it gets the job done. A better solution would be appreciated!
Just curious. When developing with Casini development server, one has an infinite number of ports. But, the production servers seem to give a particular importance to port 80.
Has that to do with a technical requirement, a convention, or both? I've checked the web but haven't been able to find a clear response so far.
Thanks for helping.
Many services have specifically-assigned ports This allows users to type, for example http://stackoverflow.com and get the website for SO, without needing to enter a port as well. This isn't a technical requirement; however, using a different port requires the user to know an extra piece of information, which must be entered into the URL every time.
When you connect to a server via TCP/IP you specify particular port you connect to. You do not connect to a server and hope that server guesses which port you would like to talk to.
So in most cases you tell browser to use protocol http, say "http://example.com/" then browser uses default port number assigned to that protocol (http) to connect to server "example.com". In this case port is 80. If for example you specify "https://example.com/" then browser looks for default port for https and then connects to port 443 instead.
So if you do not want to tell to every of your users to specify some non-default port for your service (say "http://example.com:60765/") you better use default one.
BTW there is a way to get port number your service listens to by it's protocol name (by asking a service's host's daemon at port 0) but this method seems to be rarely used (if at all).
See also other answers: default protocol numbers are assigned by IANA
It's a convention: you can use whatever port you feel like. You can look at the evolution of RFCs to see when the convention was official (http://www.faqs.org/rfcs/rfc1700.html)
You can see in the RFC 1060 (http://www.faqs.org/rfcs/rfc1060.html ) that it's the ISO Internet Protocol :)
In a production environment your web server is embedded in a server infrastructure (firewalls, proxies) protecting you against attacks from the internet. In such an environment port 80 is normally open for HTTP traffic. If you use this port there is no need to configure your server infrastructure.