So I am kind of new to networking and I'm just interested in the client/server architecture. Let's say you developed a program and the client version ran on a computer and the server version on the server(obviously). In order for the client to connect to the server, it would have to know the ip address of the server (and the port attached so it can be routed to the correct computer/program). Does that mean that the server's ip address can not change? Would you have to specifically tell your ISP to keep the ip address static? Because if both the client and server ip addresses change, then they would have no way to connect and the program wouldn't work... in other words there has to be one constant. When you sign up for a VPS do they give you a static ip address you can bind to from the client version? Thanks!
In order for the client to connect to the server, it would have to know the ip address of the server (and the port attached so it can be routed to the correct computer/program).
Correct.
Does that mean that the server's ip address can not change?
No. In fact, IPs can change at any time. Most servers that are exposed to the public Internet have a static domain name registered in the Internet's DNS system. A client asks DNS to resolve the desired domain name to its current IP address, and then the client can connect to it. But even in private LANs, most routers act as a local DNS server, allowing machines on the same network to discover each other's IP by machine name.
The OS typically handles DNS for you. A client can simply call gethostbyname() or prefferably getaddrinfo(), and the OS will perform DNS queries as needed on the client's behalf and return back the reported IP(s).
Would you have to specifically tell your ISP to keep the ip address static?
You can, but that usually costs extra. And it is not necessary if your server is registered in DNS. And there are free/cheap DNS systems that work with servers that do not have a static IP.
Because if both the client and server ip addresses change, then they would have no way to connect and the program wouldn't work...
That is where DNS comes into play.
in other words there has to be one constant.
A registered domain name that can be resolved by DNS.
When you sign up for a VPS do they give you a static ip address you can bind to from the client version?
It depends on the VPS service, but a more likely scenario would be you are assigned a static sub-domain within the VPS service's main domain. For example, myserver.thevps.com. Or, if you buy your own domain (which can be done very cheaply from any number of providers), you can usually link it to the DNS server operated by your VPS service.
Related
I'm trying to implement a web server on my pc, connected to router.
Since my PC is connected to router, It identifies private IP address, starting with
192.168...
However,it could not accept any clients that is not connected to the same router, even I specified tried with public IP address.
Is it possible to implement Web server that can be accept clients from anywhere with my PC connected to local router?
Or should I connect my web server directly to public IP directly without router?
It'll be pleasure to learn from your answers.
The problem may be, that your web server routing may not be configured correctly to your external IP, or your web server ports may be blocked, or another possibility is that your firewall is blocking your service connections outside the local network.
So, a solution to misconfiguration would be, to forward your port to your internal IP of the web server from your router menu.
And, for the case of firewall blocking, you may give special access to your web server through the firewall by setting inbound and outbound rules.
And if all that is correct then most probably your ISP(Internet Service Provider) is not allowing ports to be opened to you, maybe due to dynamic IP or service restrictions.
For the similar problem, you may refer to my answer to another post Here
What router do you have? go into the router using a web browser, mine is 192.168.0.1 with username and password as admin. or username admin, password blank.
Then set a dmz route or for port forwarding 80 to you own internal IP address.
I need to run an XMPP server for IM with end-to-end encryption and voice calling. I'm trying to set up Prosody, but is it possible to run an XMPP server without a domain name? Without own DNS server and VPN network between clients?
Short Answer: Yes.
You can still configure a XMPP domain for your server. According to the standard, it doesn't has to be an DNS Name or IP address. Something like myserver is fine. Quoting RFC 7622 ยง 3.2:
The domainpart for every XMPP service MUST be a fully qualified domain
name (FQDN), an IPv4 address, an IPv6 address, or an unqualified
hostname (i.e., a text label that is resolvable on a local network).
But if you don't have a DNS name, then clients won't know automatically how to reach your server. Which means you have to configure the IP address and the port in every client.
You can use an IP address instead of a domain name, but if that address will be changing on a regular basis, you'll probably need modifications to standard XMPP servers and clients, as they'll not be expecting that.
I went through many Prosody tutorials and I think it is not possible to set up server based only on IP address and using SSL. I even have not found how to configure Prosody on local network with SSL and resolvable name like raspberry.local. My client always gave server not found, or incorrect communication.
Sorry if I have this in the wrong community but I'm hoping one of you can help me out anyway.
I have a web hosting account with a UK company who I'm happy with, but I'd like to set up a little hosting account from my laptop, just to see if it's possible and easy enough to do really.
Trouble is I've been doing a lot of research online but coming up empty whenit comes to more of a "complete guide". Do any of you know of a good resource for setting up a home server for publishing "Live" websites with custom TLD domain names? I have a localhost server running and files hosted on there but I'm really looking for help with the IP and DNS parts for the custom domains.
For reference, I have a machine running Win7, Appserv 2.5.10, UK broadband and a .co.uk domain name registered with 123-reg.
Any help would be hugely appreciated.
You'll need to:
Point your domain to your laptop.
If you get static public IP address from your ISP, then you can just point the A record to this IP address.
Where do I set this A record? Almost all domain registrars give you a nameserver for free. You point your domain to their nameservers (generally ns1.somedomain.com and ns2.samedomain.com etc.). In the nameserver config, create a A (stands for authoritative) record and put in your static IP address.
What if my ISP doesn't give me an static IP address? This is where services like dyndns come into picture. They give you an agent that you'll install on your laptop, it detects the change in IP address and automatically updates the Nameservers accordingly. There are some free variants of dyndns as well if you don't want to spend money on this.
But my laptops IP address is something like 192.168.x.x and my site runs on localhost (127.0.0.1)? Your laptop is most likely NATed. Think about your public IP address to be that of your router. You will need to forward any connection coming to your router on port 80 or 443 to your laptop's (192.168.x.x) corresponding ports. This is called Port-Forwarding and all routers support this. Port-Forwarding is done by logging on to the admin interface of your router (Many times its at http://192.168.0.1 or http://192.168.1.1).
But again my application is accessible at localhost? You need to make sure your apache/nginx listens on 0.0.0.0 or atleast 192.168.x.x interface. This is how computers outside your laptop will be able to make connection to your laptop on port 80/443.
I have been trying to learn socket programming in C++ and got some progress for the basics. But I understood that basics are not fundamentals.
One of those fundamentals is about the question which is stated in the title. Lets say I have two separate applications running on the same computer. One of them has a server socket and the other one has a client.
When the server gets an IP address automatically, how can client find the server? Do I have to assign an IP address that is known by the client? In that case, maybe that IP address is not available on the network.
Or can client find and connect to the server by sone kind of name or id?
Have the server bind to all interfaces and have the client lookup 'localhost' by name; it's resolved locally, (ie. no external DNS service required), to an IP address stored in a 'hosts' file, and is set by default to 127.0.0.1
Google 'hosts file'
The IP address of any server in the same host is 127.0.0.1 unless the server has bound to a specific, different IP address. As #MartinJames points out, you can use 'localhost' as the hostname for that, except on certain broken Linux distributions.
How is it possible to access an internal resource (email server / FTP server) using its external IP address but from within the network ?
The situation is that a number of users have laptops and work out of the office several days per week. I don't want them to have to change the connection details from 217.x.x.x to 10.0.0.x every time they come into the office, then back again when they leave.
I have external access working, so they can connect using the 217.x.x.x IP when on the road, but it doesn't work when they are in the office.
We have a router providing NAT access to the net and different servers for FTP, email etc.
This is what DNS is for - your external DNS provides the 217.x.x.x address for the names, while your internal DNS returns the 10.0.0.x IP address. Clients access resources by hostname, not IP address, and it's done.
Unless you have filters forbidding access to the external NAT'ed address from internal clients, I do not see why it should not work.