I have setup a windows 2003 ftp server and using chilkat to connect to this ftp inside my customized application. My application is developed in VB6 with ftp support of chilkat. The application works on different places of the city and connects to my ftp. Unable to access ftp and transfer files using the customised application, from some networks like idea netsetter / bsnl. It works perfect on other networks.
Thanks in advance.
Regards,
Sam
This is likely to be a firewall issue at the client end. FTP is often blocked by firewalls.
Just as well, FTP has its problems making it a less than ideal alternative. There are better options such as SFTP or FTPS but support for those is limited in Windows and you'll have to buy both server and client pieces to use one of them.
Fewer firewalls block HTTP and HTTPS though some are finicky enough to block traffic that doesn't look like Web browsing. Stiil, your odds of success go up substantially.
An obvious choice might be to use WebDAV. IIS supports WebDAV and it is pretty easy to write simple WebDAV client logic in VB6 based on one of the many HTTP components available. I'd probably use XmlHttpRequest or WinHttpRequest for that. A search ought to turn up several VB6 classes written to wrap one of them to support WebDAV client operations. You can also buy WebDAV client libraries.
Stick to using HTTPS (which means you need a server cetificate for IIS) and you won't have passwords going over the network in the clear. Even if you use HTTP you'll be no worse off than using FTP, plus it'll work through the vast majority of firewalls except those that specifically block non-browsing HTTP requests.
This could be a firewall configuration on the Client or Server. You're not going to be able to do much about the client, but for the server it may depend on whether your doing Active or Passive FTP connections.
If you are doing Active connections, make sure ports 20 and 21 are open.
If you're doing Passive connections, you may want to check out this article about configuring the PassivePortRange in Server 2003 FTP- http://support.microsoft.com/?id=555022.
Related
Is there any protocol, API or software in existence that can send data/IM/etc directly from one device to another with no server?
Can you not use HTTP GET/POST/DELETE directly between two devices when their device data is known to the user(s)?
I would very much like to know if there is ANY software/protocols that can do this.
thank you!
The internet is build on the Internet Protocol suite. This suite has 5 different layers of protocols: The physical layer, the link layer, the network layer, the transport layer and the application layer. Each depends on the one before.
If you just use the browser, by default HTTP (application layer) is used, which relies on TCP (transport layer), which relies on IP (v4 or v6, network layer), which relies on ethernet (link layer), which finally relies on the actual cable that's plugged into your computer (for WiFi, the first three are the same but the last two differ if I'm not mistaken).
Now to your question: Is there any protocol, API or software in existence that can send data/IM/etc directly from one device to another with no server?
Yes there is. I suggest you start looking at protocols that are in the application layer. To highlight a few standards next to HTTP(S): FTP is for file transfer, IMAP is for emails clients, SMTP is for email servers and SSH is a secure shell which can also be used to tunnel data through.
For your specific case, I think either FTP (FTPS if you want it over SSL), or SSH can be a solution, but it's hard to know for sure without the specifics.
The only thing that these protocols have in common is that one of the two computers will act like server and the other computer as client. This has as downside that port-forwarding might be necessary.
If you've chosen the protocol you'd like to use, then you're up for the next step, selecting a program that can do that for you. For HTTP(S), I'd recommend Apache. If you're using Linux and chose SSH, then you're in luck, there is a build in SSH server in Linux, you can use that. For other protocols, you might just want to search yourself, as I do not have any suggestions.
I hope this answers most of your questions!
Desirius
In browser context, WebRTC is probably what you are looking for: It allows user to user communications.
https://en.wikipedia.org/wiki/WebRTC
https://webrtc.org/
Need to be able to continuously receive calls when a Chrome webpage is open. How do I do that even for users who are inside a strict enterprise network?
WebSockets? (but there's the proxy problems that doesn't know what wss:// is)
HTTP? (but will I have to poll?)
Other?
Since you included the "vLine" tag, I'll reply with some information on how our WebRTC platform will behave in an enterprise network. vline.js will use a secure WebSocket by default if the browser supports it and fall back to HTTPS long polling. As described here, the secure WebSocket may work depending on the exact proxy configuration. Feel free to test it out by using GitTogether or creating your own vLine service for testing.
I have an app, and it makes an https connection to a server. Is it possible to use something like wireshark or charlesproxy to just see the useragent that it's connecting with? I don't want to see any of the actual data, just the useragent - but I'm not sure if that is encrypted as well? (and if it's worth trying)
Thanks
Is it possible to...
No. Browser first establishes secure connection with server, then use it for transfer all data including requests' data, various headers etc.
Too late for the original inquirer, but the answer is that it may be possible in some cases, depending on application implementation.
You can use fiddler, and by turning on the 'decrypt https traffic' you also have visibility to the HTTPS content in some cases.
What fiddler does (on windows at least) is register itself within the wininet as system proxy. It can also add certificates (requires your approval when you select to decrypt https traffic) and generates on the fly certificates for the accessed domains, thus being MitM.
Applications using this infrastructure will be 'exposed' to this MitM. I ran fiddler and ran a few applications and was able to view https traffic related to office products (winword, powerpoint, outlook) other MS executables (Searchprotocolhost.exe) but also to some non-microsoft products such as apple software update, cisco jabber)
How does Netnanny or k9 Web Protection setup web proxy without configuring the browsers?
How can it be done?
Using WinSock directly, or at the NDIS or hardware driver level, and
then filter at those levels, just like any firewalls soft does. NDIS being the easy way.
Download this ISO image: http://www.microsoft.com/downloads/en/confirmation.aspx?displaylang=en&FamilyID=36a2630f-5d56-43b5-b996-7633f2ec14ff
it has bunch of samples and tools to help you build what you want.
After you mount or burn it on CD and install it go to this folder:
c:\WinDDK\7600.16385.1\src\network\ndis\
I think what you need is a transparent proxy that support WCCP.
Take a look at squid-cache FAQ page
And the Wikipedia entry for WCCP
With that setup you just need to do some firewall configuration and all your web traffic will be handled by the transparent proxy. And no setup will be needed on your browser.
netnanny is not a proxy. It is tied to the host machine and browser (and possibly other applications as well. It then filters all incoming and outgoing "content" from the machine/application.
Essentially Netnanny is a content-control system as against destination-control system (proxy).
Easiest way to divert all traffic to a certain site to some other address is by changing hosts file on local host
You might want to have a look at the explanation here: http://www.fiddlertool.com/fiddler/help/hookup.asp
This is how Fiddler2 achieves inserting a proxy in between most apps and the internet without modifying the apps (although lots of explanation of how-to failing the default setup). This does not answer how NetNanny/K9 etc work though, as noted above they do a little more and may be a little more intrusive.
I believe you search for BrowserHelperObjects. These little gizmos capture ALL browser communication, and as such can either remote ads from the HTML (good gizmo), or redirect every second click to a spam site (bad gizmo), or just capture every URL you type and send it home like all the WebToolBars do.
What you want to do is route all outgoing http(s) requests from your lan through a reverse proxy (like squid). This is the setup for a transparent web proxy.
There are different ways to do this, although I've only ever set it up OpenBSD and Linux; and using Squid as the reverse proxy.
At a high level you have a firewall with rules to send all externally bound http traffic to a local squid server. The Squid server is configured to:
accept all http requests
forward the requests on to the real external hosts
cache the reply
forward the reply back to the requestor on the local lan
You can then add more granular rules in Squid to control access to websites, filter content, etc.
I pretty sure you can also get this functionality in different networking gear. I bet F5 has some products that do some or all of what I described, and probably Cisco as well. There is probably other proxies out there besides Squid that you can use too.
PS. I have no idea if this is how K9 Web Protection or NetNanny works.
Squid could provide an intercept proxy for HTTP and HTTPs ports, without configuring the browsers and it also supports WCCP.
F
Is there a way to monitor the FTP port so that I can know what commands my FTP application is sending to a FTP server?
I am using a closed-source FTP client application, which is not working with a closed-source FTP application server. The client and the server are not communicating well with each other, and I would like to find out why. I wish to reverse-engineer the client to see what commends the client are sending to the sever. I used a web test tool before that allowed me to monitor the content transferring through HTTP, but I can't seem to find such tool for FTP. I appreciate it if you can help me out, thanks.
Sounds like you need a packet sniffer - assuming your network admins/company policy allows it...I have used wireshark fairly successfully before.
The core FTP commands should be visible in the packets.
You can use the Wireshark application: http://www.wireshark.org/
It should have decent parsing capabilities for FTP as well as other protocols.
Can you configure a proxy with the client? Then you could install an ftp proxy server using the logging on that to see what's going on?
There's a proxy server for Linux here: http://frox.sourceforge.net/doc/FAQ.html
Paul.
Do you have access to ftp-server logs? Its likely those commands would be logged there.
If they aren't, your next option would be to configure the server to log them, if you have access.
If thats not an option or server does not log such things, then you have to go to either packet sniffer or a proxy, as suggested by previous posters.
On Unix, tcpdump might be your friend. Maybe you should first state which OS you're targeting, though.
If you have the ability (often requiring root access) to use a packet sniffer, tcpflow sniffing the TCP control channel will show you the commands and responses going back and forth in an easy-to-read format.
If you don't have such access, tools such as ktrace and strace will allow you to see all data read and written on the socket for this connection, though it will be a little work to extract it.
If you could tell us just what tool you were using for HTTP traffic, that would allow us to look for something similar for FTP traffic.