I have a linux server has an ad-hoc wireless network for clients to connect to. Once connected I want users to always be redirected to it's own web server no matter what URL they type in. The large solution would be to set up a full DNS server (with BIND or equivalent) but that seems like overkill. All I need is a simple program that will listen for any DNS request and always respond with the same IP address.
I looked around for one but couldn't seem to find one. It would preferably be written in C or Perl as I don't really want to install any other scripting languages.
Use Net::DNS::Nameserver and write your own reply handler.
For C, look at:
How to Build a custom simple DNS server in C/C++
Create custom DNS name server in C
I would suggest using dnsmasq. It's more full-featured than you absolutely need, but it's very well-written, small, and easy to install, and the only configuration you would need to give it is --address='/#/1.2.3.4' to tell it to answer all queries (that don't match some other rule) with the address 1.2.3.4. dnsmasq is well-known and maintained and probably a more robust server than Net::DNS::Nameserver.
I've used fakedns.py when reversing malware. It may be too limited for your situation.
As I answered in the other related question, I wrote a basic DNS server in C++ for a job interview under BSD license.
I think the code was pretty clean, though I didn't made unit tests :-(
I tested it with dig, and it took about a week understanding DNS protocol + implementing + documentation.
If anyone would want to extend it, I guess it would not be very difficult.
Because I think it only supported inverse queries, as that was asked in the exercise.
The code could be found here:
http://code.google.com/p/dns-server/
It was migrated to: https://github.com/tomasorti/dns-server
Related
I was tasked to set up an open-source icap-server to scan files that are uploaded in one of our web applications.
The files base64-encoded withing the upload method and this seems to lead to the fortigate not being able to scan it properly.
Now I managed to set up an icap-server using "c-icap" and tested it with "clamav". So far it seems to work, at least EICAR files are detected.
Now the problem is, that my boss is basically a "Windows-only" person who says that any open-source AV can´t be trusted enough.
He wants me to try to have the requests/uploads sent to the c-icap server, but scanned with Windows Defender. ß Is there any - useful - way to accomplish this? Also, since I am super new to ICAP - are there any restrictions regarding which icap-server can be used?Like, is there any way to force requests to be handled with a metadefender-icap only, and not any other icap server?
Sorry if these questions are a bit unspecific and basic, but just started with ICAP yesterday!
Thank you!
Check out this link: https://techcommunity.microsoft.com/t5/windows-it-pro-blog/metadefender-icap-with-windows-defender-antivirus-world-class/ba-p/800234 to see what Microsoft offers regarding Defender+ICAP.
I have used commercial ICAP solutions in the past (like Bluecoat) that allow plugging in multiple commercial virus engines (Kaspersky, Sophos, ...).
These are appliances, and you don't need to tell your boss their internals are probably some sort of Linux ;-)
You can probably also set up a commercial antivirus solution on your Linux system and use that.
Looking at this link: https://learn.microsoft.com/en-us/windows/security/threat-protection/microsoft-defender-atp/microsoft-defender-atp-linux it may even be possible to run Microsoft's Defender on Linux. I haven't tried it myself though.
Unlike your boss, Microsoft realizes software shouldn't be made to just run on Windows anymore (even MS-SQL Server now runs on Linux).
I'm looking for the simplest possible (cross-platform, but not necessarily cross-browser) code to send data from a local web page to a C (not C++) application running locally. Basically, I have an HTML page with a form and I want to send the data from that form to another process in the simplest way possible. (I know that I can read local data from a webpage relatively easily, especially now with HTML5, but writing outside of the javascript sandbox is a mystery.)
I know that browsers make this very hard to do for security concerns, and I don't want to open up my machine to attacks, but maybe I can run a very simple server inside the C application to receive the submitted data... Either way, I cannot run any standard webserver, so I need to have a C library/app that does it for me.
I've looked into .hta files (seem to only work for Windows) and some C web servers (all I've found are *nix specific). A similar question is how to transfer of data from webpage to a server c program , except that user allows the use of Java and other webserver platforms (I must use C).
UPDATE: Promising libraries: https://stackoverflow.com/questions/175507/c-c-web-server-library
Have you considered FastCGI? I have a fast CGI library written in C that might be helpful. It still needs a lot of work and I'm not sure if I would want to use in a production environment.
If you find any bugs or make any enhancements, please share them so that it can help others.
https://github.com/manvscode/shrewd-cgi
You could write a very simple web server in C, serve the page from it (avoids security issues), and post the form to it.
If you're bound to c, you'll have to go low-level and deal with all the nifty details around the sockets library. (There's a reason why people abstract that in high-level languages). Check out some example code for RPC in C with server and client here. If you can afford to bind to C, e.g. using Tcl, i would implement the server in a tcl script and bind your C functions as a Tcl command. That way you pass the content directly to your c method while avoiding to write all the sockets code low-level.
Send the desired data from web to specific port of your system (for example port X). Then run your application (e.g. APP) in background using following command:
nc -l X | ./APP
And of course you need nc package.
I need to open a lightweight X server in C language. I figure vnc may be lightweight enough and universal in all Linux flavor and windows. Is there a C API to start vnc server? What libraries does it need?
If you know the name of the binary (executable) that you want to start, you can probably just use system() to start it. Assuming the binary is in /usr/bin/vncserver:
system("/usr/bin/vncserver");
Note though, as pointed out in a comment, that your question is fairly confused. A VNC server is not an X server. It's perfectly possible to run a VNC server without running X "inside" it. So starting a VNC server will most likely not help with your problem. I suggest you post a new question with a more clear description of what you're trying to achieve, this sounds a lot like you're "jumping" to a solution.
I want to create an application in C that allows two users to share a file. I'll call the person sending the file the server and the receiver the client. There are a few requirements:
The users need no identification, no "login". You could say they are unknown for my application.
The server selects a file for transfer and gets returned a simple ~10 character ID string/hash that the client can use to retrieve the file.
The same application is used for both serving and receiving.
My application must not need dedicated software running on a remote server, unless it's freely available (e.g. bittorrent trackers).
Now this sounds a lot like bittorrent and I am seriously thinking of doing this through bittorrent. I'm not sure how I would do this. Are there any good libraries for torrent creation / seeding / downloading?
Please answer this question by either:
Posing a viable alternative for bittorrent / other ideas.
Posting good libraries / snippets / implementations of the bittorrent protocol in C.
This does indeed sound like something best done with BitTorrent. Have you had a look at libbt? It's not very well documented but does include a sample client, which is btget.c in /src/.
I have now found this library: rasterbar libtorrent. It's in C++ but I don't mind (I don't know either that well anyway).
Sharing here for future reference if other people are looking for the same thing as me.
And an other solution, send the file through an IRC server (like Freenode). I came up with this solution after I had trouble with opening ports with bittorrent.
I have some C code that parses a file and generates another file of processed data. I now need to post these files to a website on a web server. I guess there is a way to do a HTTP POST but I have never done this in c (using GCC on Ubuntu). Does anyone know how to do this? I need a starting point as I have no clue of doing this in C. I also need to be able to authenticate with the website.
libcurl is probably a good place to start.
I think Hank Gay's suggestion of using a library to handle the details is the best one, but if you want to "do it yourself", you need to open a socket to the web server and then send your data in the HTTP POST format which is described here. Authentication can mean a variety of different things, so you need to be more specific.
Unfortunately, all of the above three jobs involve a fair bit of complexity, so you need to break the question down into stages and come back and ask about each bit separately.