To keep things simple, please allow the "assumption" that some code requires the use of a full URL, even though the domain is on the same server, i.e. a simple file path cannot be used.
TCP/IP?? Question:
If a form action target = "http://this-full-URL.com/postdata" (for example) and that URL is also on the same server, then which happens first?
A) Data is sent "out onto the web", and then returns to the same server,
or
B) Before sending any (possibly sensitive) data, the server (Linux, Apache, PHP), first "discovers" the target address is local, so (clearly) no data is sent over the net?
Thank you.
The correct answer is always A. :-)
It just happens that the case where the browser and the server are running on the same machine, "the web" will be short-circuited by the local TCP/IP stack. However, Apache and PHP are not involved in that decision; it's pure functionality of the OS networking stack.
However, if your server is behind a NAT gateway or firewall and the DNS name is resolving to the NAT gateway/firewall, the request will be routed to the NAT gateway/firewall and back to your machine. Thus, in order for the routing to stay on the same machine, the DNS name of the host of the target URL has to resolve to the actual IP address of the server machine, not be tunneled to it.
The network software will resolve the hostname to you machine, then the local TCP stack will route the request locally. Traffic won't ever leave the machine, it'll all be in memory on the server.
Related
I have a server running on my machine. I want to send a request to the server using different IP address to test a web application. I only have the machine on which the server is installed. I have been testing as a single user but now I would like to let the server think that the request is coming from a different ip address even though it is from the same machine. How can I do that?
Here are the 2 solutions that might be possible in your situation
1- To change the ip address :
Pick an ip from the free proxies here: http://www.freeproxylists.net/
And enter the info in firefox just like this page says:
http://www.wikihow.com/Enter-Proxy-Settings-in-Firefox
Note: You may pick a proxy with port 80.
Then you are good to go...
2- Or you might use a Virtual Machine installed on the same computer as the server and access the website right from it but beware not to use bridged connection.
Newbie programmer here. I'm building an app for an API that requires an IP address for authentication. Basically, users have to send the API management their IPs and then each time a computer makes a request to their server, it verifies whether it's coming from a registered IP.
Since I work in a number of different places and thus end up with different IPs, I thought it would be easiest to use DynDNS to establish a URL that points to whatever my current IP is and then send that URL to the API management. So my first question is if this approach would in fact work?
Secondly, assuming this would work, I set up ben.dynalias.com and downloaded the DynDNS Updater client. It appears to be working: the updater says status: OK and displays my current IP. However, when I navigate to the URL (ben.dynalias.com) there's no response. Should this be the case? How can I tell if it's working?
I don't see any reason it shouldn't work as long as your updaters aren't overwriting each other by running at the same time automatically from different locations.
You can ping ben.dynalias.com and see if your current ip matches.
I just hosted ben.dynalias.com and it gave me your IP.
Since there is no web server running on that IP, then your browser will not be able to show you a page result.
You can use http://www.kloth.net/services/nslookup.php
to check and see if you get the correct IP from a host lookup.
Depending on how often your IP changes this might not be a great solution as the DNS will cache your hostname and will not try and resolve it again until the TTL expires normally minimum 1 hour.
whether the API management accepts a hostname instead of an IP address is a question only they can answer. Some will, many won't as it's "easier" to hijack a domain name than to hijack an ip address.
trying to browse to you-address.dynalias.com that points to your own public address rarely works, even if you opened up the right ports because your router will be highly confused. The best way to test such a setup is by using a phone or tablet with 3g/GPRS internet - of course after you set up port forwarding in the router to point the appropriate port to your computer.
When there genuinely is no web server installed on a machine, and the user types in the machine's IP address or FQDN into the web browser, the user will get a genuine "can't connect to the server" message from the web browser.
However, after installing the Apache web server, the direct IP address and the FQDN (i.e. archimedes.example.com) will now show the default "It works!" page. How can I make my server act as if there is no server in these places (for the IP and the FQDN)?
Note that a 404 error does not qualify, because that makes it clear that a web server is available.
Is this even possible to do in the first place?
The goal of this is that I just want my regular websites, say genuinewebsite.com, that is genuinely supposed to be on this server to be recognized. All the other "default" addresses (the IP address and FQDN) that really have no connection to any websites should just act as if there is no web server there in the first place.
No, it is not possible, because to get the hostname the browser used for the request, the browser first has to connect successfully and send it in the request. By that time, you can't really refuse the connection; the best you can do is close it on them which will appear as a connection reset error.
I created an AMP web application that was originally going to be served from a traditional 3rd party host.
As we finished up, the client decided to host it internally, on a server in their office network. The application is only meant to be available to staff members, but those staff members will often be off-site. I had no involvement in setting up their network, which uses at least one server running windows server 2003. The client machines I saw were XP.
I set up Apache, MySQL and PHP on the server 2003 machine, and installed the application. The application is built on the CodeIgniter framework, so I set the base_url to the internal IP (192.168...), and we tested from within the network. Everything worked fine.
Next, we asked their network guy to open port 80 for apache. I set the base_url to the external IP, and tested from my home (using the external IP as the web address), and it works fine.
However, when attempting to access the application using the external IP from within the network, they're unable to connect. I can reset the base_url to the network IP, and they can access it using the network IP, but then it the application fails when connecting externally (since the base_url, used throughout the application, is pointing to the internal IP).
It suppose I could let CodeIgniter determine the base_url (by leaving the variable as an empty string), but would rather figure out why the external IP fails in-network, and try to correct that.
The server we're using is not dedicated to the AMP stack (in fact, it has at least one other application broadcasting to the internet that must have been using IIS, as well as an FTP server used for office scanners), so I suppose there might be some conflicts there.
I know very little about windows networking. A quick search suggested this might be because of NAT, but didn't offer a work-around.
Their network guy has no suggestions, and said that everything should be fine.
Is it possible to have users inside the network access the Apache server using the external IP, and if so, what needs to happen to enable that?
TYIA
Your client's NAT router is configured to forward packets arriving on its external interface for its external IP with port 80 to the internal machine, port 80, after re-writing the source and destination IP addresses in the packets.
From within the network, attempts to connect to the external IP address will be routed to the default route on the machines, the router's internal interface. This interface is not configured to forward packets back into the network.
Configure the application to listen on all IP addresses. Make sure that the server knows that the clients know it under several hostnames -- the internal IP address and the external IP address.
You might be able to re-write the NAT firewall rules on the router to perform the port forwarding for the internal interface as well, but off-the-shell equipment common in homes and small businesses do not make this task easy. More expensive gear (or home-built *BSD/Linux router machines) can do this without much effort, but it would needlessly add traffic to the router.
This isn't Apache related, nor is it CI related. It's often impossible to reach the external IP address from within the network.
Frankly, I don't know exactly why that is. I do know that it's related to how NAT (Network Address Translation) works or at least how it's implemented.
For a detailed overview of why this is, you should ask this question on serverfault. If you're simply a programmer who has to deal with it, accept that NAT usually works only from inside to outside and outside to inside, but not inside to inside.
You already mentioned one of the solutions in your question - don't use base_url. You could also simply run the server on an external IP address (not your company IP, but let's say a datacenter or something).
First URL stands for Uniform Resource Locator. It will be very difficult to remember an IP address. Instead of remembering the IP addresses URL came like www.intrepidkarthi.com. Url normally contains three parts. For example http://intrepidkarthi.com/index.php. Here "http" refers to the protocol it uses. Then the server name and then the requested file name.
Here I have enlisted the flow of working mechanism behind your browser
The flow of work
Your browser communicates with a name server to translate the server name "www.intrepidkarthi.com" into an IP Address, which it uses to connect to the server machine. * So your browser will see if it already has the appropriate IP address cached away from previous visits to the site. If not, it will make a DNS query to your DNS server (might be your router or your ISP's DNS server). DNS stands for Domain Name Server - For exapmle if you want to get karthik's phone number then you will look into your telephone directory. Likewise your computer doesn't know intrepidkarthi.com's IP address . So it looks into DNS.
The browser then formed a connection to the server at that IP address on port 80. HTTP protocol uses port number 80
The browser sends a GET request to the server, asking for the file "http://www.google.com/karthikeyan.htm". The webserver then returns the requested page and your browser renders it to the screen.
The firewall will control connections to & from your computer. For the most part it will just be controlling who can connect to your computer and on what ports. For web browsing your firewall generally won't be doing a whole lot.
Your router essentially guides your request through the network, helping the packets get from computer to computer and potentially doing some NAT (Network Address Tranlator) to translate IP addresses along the way (so your internat LAN request can be transitioned onto the wider internet and back).
I don't know what I understood is correct or not. I need to understand it completely till the hardware level at the back.
browser has no DNS cache. your operating system's tcp stack has.
the server name in DNS may have many IP addresses. the browsers usually choose one at random.
DNS is a tree. to get www.google.com, you go to google.com name service and get IP of the computer www.
returned HTML page is a small part of the information. In turn, it points your browser to establish many connections to other servers, to bring scripts, pictures, etc.
otherwise okay.