Encrypt Some Basic Data Being Sent From Server To Client?
Oct 11, 2009
I need to encrypt some basic data being sent from server to client.
I was going to open a file in bytes, convert it to chrs (Modify odd numbers by adding 2 and even numbers by adding 3) then use Base 32 (Triacontakaidecimal) or Base 16 (although base 16 will occupy twice the space). Convert the data back to bytes and after do the same with the decryptor.
About using base 32, is there some sort of class in vb.net or maybe an api?
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Mar 30, 2009
I've basically made a basic tcp server/client application. The thing is that I'm behind a router and so will be the other people that use my clients. I've had to use port-forwarding or the software "rinetd"to run quite a few applications online.
Let me explain: I'm on a lan network that connects to the internet. Whenever I want to host a server - for instance a basic ftp or http server. If I give my external IP to anyone, they won't be able to access my server. Even if I portforward, it doesnt work. I have to use rinetd here. For other applications, portforwarding works. I'm not sure how these things work at all.
Anyway, my issue now is that I have created this server/client application. I'm having serious doubts that if I run the server, I'll have to either a) portforward or use rinetd to get people to connect to my server. IF I need to portforward, that's fine. However, using rinetd would really suck... My 2nd concern is as follows: IF the person running the client is in a similar situation as me (i.e he's on a lan that has a router which connects to the net), will he have to portforward or use rinetd as well? If he portforwards that's fine. But I don't think I could get people to use rinetd.... Also, if there are more than 1 person on a lan trying to connect to my server, there is a big problem when they try to portforward: they will only be able to allocate one of their internal ip to that port, and the others won't be able to connect, right? How does this work? I mean, I use many softwares like msn/skype/(some games)/firefox that do not need portforwarding/rinetd. Yet they work. My housemates(other people on the lan) use the same softwares, and it works fine. There's no clash/probs watsoever How come these run fine?
Anyway, back to my issues. Given I have no knowledge about how the above work, I was wondering whether there was a way to host a vb .net server application on an external website (external to my house) so that I might *avoid* the above mentioned problems, and to what extent that would be a sound solution.
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Jun 27, 2011
Hey guys, I am trying to send data from client to server (encrypted) and the string sent from the client is not the same as recieved from the server. I've been killing my brain for hours to get this to work but I cant manage. Im converting everything to Base64 string.
Client:
Public Sub SendMessage(ByVal msg As String)
Try
SyncLock myclient.GetStream
sw = New IO.StreamWriter(myclient.GetStream)
[code]....
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Jan 6, 2011
Im trying to make a basic Client/Server. The server can handle multiple clients and each client can send /recieve messages from the server.It works fine with just 1 client. but as soon as i connect with a second client. The first one no longer works. Anything sent from the first client is ignored by the server and when running the server in debug mode it gets errors from the client 1 stream.
Its as if the server will only hold one stream at a time and whenever another client joins the other streams are shut but the new client works fine. Even though i never close a stream.
[Code]...
Edit: FINALLY FOUND IT! Stupid mistake i forgot to put the ClientN variable up by one for each new client.So i was creating a new space in the array but erasing the first slot for the new client
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Jan 6, 2010
However I have hit a massive brick wall with my program. My program that I'm trying (can't emphasis this word the importance of that word) to create a Client/Server chatroom using TCPClient in Visual Basic. So far I can get my client to speak to my server. However, i'm trying to get the returned data to display in a listbox which never happened, i then tried a label, which again never happened then a text box which I'm sure you can figure out how that went! I'm not great at networking programmers nor am I not bad I'm terrible but duty calls when it comes to projects.
The code I currently have was mostly taken from the net but when I have the program fully work and I understand how the software works I intend to heavily modify for it to suit the needs of what I need to achieve. where I can get my client to display the data from the server that I have already sent to the server (which displays successfully within the server).
[Code].....
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May 31, 2009
I want to make a basic winsock chat server and client, and I just need to know the basics, like.How do you determine where to send the data?How do you determine where to receive data from?How to actually send and receive the data?I just don't want to read from a website that has a lot of extra information. I just want to start off with the basics so I can actually learn.
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Feb 28, 2010
Here's an interesting problem, and I'm looking for a pattern that will keep it all workable. I am building a smart-client app for a school system. It will contain information about students including their report cards, sick days, and so forth. it will generate student-level reports, including their report cards, each rich with very personal commentary by their teachers. The app will retrieve data from the remote server via web services.
[Code]...
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May 9, 2009
how to create a client/server... But I couldn't... I don't want anything fancy. Just want the client to send the server 4 numbers, depending on the user's choice; after that, the server would turn off the pc, restart it, etc. It all depends on the number received. Is there a rather "simple" way to do it? If it's not to much trouble you could use Atheist's example. (Btw I don't understand the code and, yes, I've checked on [URL])
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Jun 13, 2010
I am a student and trying to start a programming career, my colleague asked me to make a multi tier or multi client desktop application for the schedule tracking using xml as a database; however the desktop application would be deployed in one or more computers but my leader can monitor the info from her office in addition she wanted me to put administrative privilege to avoid unauthorized access in some database features of the system. an info regarding multi-client desktop app.
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Apr 19, 2011
I have a small program which is a tcp client. I send a string from this client to a device over ethernet (it acts as the tcp server). As soon as the device recieves the input string it will respond back with response data. My problem is i am not getting the entire response data back from the server. (device).
Dim serverStream As NetworkStream = clientSocket2.GetStream()
Dim outStream As Byte() = System.Text.Encoding.ASCII.GetBytes("my-cmd")
serverStream.Write(outStream, 0, outStream.Length)
[code]....
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Jun 21, 2010
We are creating a Who wants to be a millionaire style game in VB. Our server is pulling information such as questions and answers from a Access Database and sending them to the contestants (Clients). All transfer of information is directly from the server to each client. One of the "Life Lines" we want to use is "Ask a friend", where one client is able to Instant message another client for a short time to get help on the question.
[Code]...
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Feb 26, 2010
Can you compress data being sent from client to server and etc? If so how would i do this?
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Jul 12, 2011
i am creating a software that needs to transfer data between client and server. i m storing the data in client in a database. but how does server access every clients data.
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Jun 30, 2011
I have a Linq query on the server side of a Silverlight 4 Ria project that returns a number of distinct items based on a time period(Month).The problem I am getting is when the client callback fires the data has been corrupted and all the items returned from the server are duplicates of the last item in the collection.
Server Call
Public Function GetBusinessHeadCountHistory(ByVal businessUnit As String) As IEnumerable(Of EngineeringHeadCountBusinessHistory)
Return From t In ObjectContext.tblTimes
[code]....
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Aug 20, 2010
I have programmed a chat application in VB but as soon as I send any data from a client the server will send it to all. It should send a reply only to a particular client. This is the function I have used.
[Code]...
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Nov 12, 2011
I've been working on this project for about a year now. It's a basic clientserver chat program. After a long time of improvement, I decided to test out the strength of my server.
On the client, I fired off 200 chat messages ("FLOOD# 1"... "FLOOD# 200") to the server as fast as possible. The result: Server immediately crashes. After some slight tampering, I was able to get the server to process 135 of the 200 messages before giving up. It no longer crashes, but something different happens. The data from the client is received in order, but when I pass that message to a function (myForm.OnLineReceived), The data is completely out of order. If I add a slight delay between the calling of the OnLineRecieved function, The messages are in perfect order.
Each message from the client is first encrypted, then encoded in base64. An "-" is appended to the end so that the server can easily find the end of each data "packet".
Server Code:
Imports System.Net.Sockets
Imports System.Text
' The UserConnection class encapsulates the functionality of a TcpClient connection
' with streaming for a single user.
[Code].....
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Nov 15, 2011
basically i just want client to say "C: emp" ENTER
then, server must reply with all its files in c: emp
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Jul 23, 2008
The problem I have is: When I click on cmdListen in the server form and cmdConnect in the client form,both programs won't respond and they crash for some reason I don't know.
Client source code:
Code:
Imports System.Net.Sockets
Imports System.Text
Public Class Form1
[CODE]...
Code:
Imports System.Net.Sockets
Imports System.Text
Public Class Form1
[CODE]...
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Jul 13, 2009
For example, i installed the windows application in more than one pc. All the pc's are in network. I want to save the data in a single database. How it is possible?
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May 3, 2012
I developed a simple examination system with registration forms. I used VB.Net as the programming language. I haven't tried manual coding for my problem yet.Anyway this is a project for the company from which I am an intern. The plan is to get every client pc to have this examination/registration application and this application will send the personal info and the score to a central database(server pc).I used MySql as the dbms and developed the application on the same machine which means that the Database server I used is only on the local host.
Now I was about to try to implement the application to one client pc(as a beta test) and installed the necessary files(.net framework) and I also installed MySQL Server(and workbench) in the server pc.When I run the application in the client PC it didn't detect/connect to the ServerPC's MySQL server instance and therefore was not able to record the dummy values I input in the client application. Take note I changed the connection string of my app to point to the ip address of the serverPC.
Should I install the MySQL Server(and Workbench) to every ClientPC so that I can create a server instance that uses the REMOTE HOST option and configure it such that it will connect to the SERVERPC's Database?How should I setup the server so it gives access to the application I installed in all clientPCs?
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Mar 28, 2012
i wanted to develop an apps that sends sends data from client to server and vice versa. i want to biuld it with
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Sep 9, 2009
I need to solve the following problem:- Create a server application which generates a random number every second- Have any number of client applications access the current random number through a dll (associated to the server) at anytime How would I do this? Anyone has a prototype VB.Net code for the server which does this kind of thing? I'm pretty sure I know how to write the client code.
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Oct 18, 2009
My problem is that I would like to know that if some data from client has arrived to the server, I would know its length.Now I m getting an error at: mClient.GetStream.EndRead(ar). It is saying that ar cannot be empty. [code]
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Apr 20, 2012
I have a TCP Socket Client (using the Socket Class) that is connected to a simple TCP socket server (just for testing)I have this code snippet :
Dim aSocket as Socket
While aSocket.Connected = True
byteRead = aSocket.Receive(dataByte) 'number of bytes
[code].....
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Oct 13, 2010
I'm not sure what I have done wrong, I am trying to get my program to send data (UsernamesPasswords) from client to server, then the server says if it's right or wrong.
The error is on this line:
Dim networkStream As NetworkStream = TcpClient.GetStream()
Heres the Client:
Private Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click
If TextBox1.Text = "" Then
MsgBox("You must enter UN/PW!")
[Code] .....
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Sep 21, 2011
In our project we've decided to put an exam generator using vb.net and after generate you can send it to client computer/students. *server computer/teacher will the one who will use exam generator and send it to the client computer/student*student will recieve it and then send it back again to the server computer/teacher*teachers will going to generate an exam depends on the type of exam, so i think im going to make it a wizard type environment
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Aug 3, 2011
i wanted to develop an apps that sends sends data from client to server and vice versa. i want to build it with help of winsock in vb 2008 using tcp.
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May 16, 2012
I have a Client/ server application where the Server is in java and Client is in Vb.net.When i send large string from client to server am not receiving complete text.code attached below.
client-- VB.net-
Try
Dim clientSocket As New System.Net.Sockets.TcpClient()
[code].....
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Feb 2, 2011
I am facing problem in asynchronous socket communication.
1)I wanted to perform connect(from client to server) operation on enter button and send the data whatever client want to send and disconnect from server. And again client should get connect to server whenever client wanted to send data. this is the mechanism.
i.e how to reuse the socket.
2)Again Server should able to send the data to client.
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Jan 9, 2012
I'm creating a reporting web page as part of a standard VB.NET web application. The page is data driven, with jquery making calls to a web service local to the application to get values of elements that are dynamically created in the DOM. Ultimately these dynamic elements and their values are all wrapped up in a JSON object, so that part of the client side is fine.
Right now, I can pass that JSON object to a method in the web service which creates an SQL Data adapter from the values and queries a database. My ultimate goal is to have this client JSON data be used to query the database and construct an excel file to send back to the user, or failing that a CSV file.
It's my understanding (from working with PDF file generation) that this type of function can only be done on the server side of the web application, not even from the web service (i.e. I can't have the web service return an array of bytes and have JavaScript/jQuery present that as a file).
So, how do I go about this? Now I have my JSON object on the client side, where should I be sending it, how, and how do I go about returning my file?
I've read about either storing the JSON in a hidden field and having the server take the elements value and go from there, or using AJAX to send the JSON to the server just before a postback is made to fire off the server-side function to run the query and return the data.
I just need a little guidance, and a little help understanding where to use the hidden field, or what I am actually doing with the pre-postback AJAX call.
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