Parsing Telnet Commands?

pbd22 · Joined: 08 Aug 2007 Posts: 5

Hi.

Anybody know of any good code examples out there on
how to take a telnet command and parse it?

Thanks!

Archived from group: microsoft>public>dotnet>languages>csharp

Nicholas Paldino [.NET/C# · Joined: 08 Aug 2007 Posts: 71

There is a sourceforge project which claims to parse telnet commands:

http://dotnettelnet.sourceforge.net/

There are some other commercial offerings, I believe.

In the end, you can always do it yourself, using the protocol reference:

http://www.faqs.org/rfcs/rfc854.html

--
- Nicholas Paldino [.NET/C# MVP]
- mvp@spam.guard.caspershouse.com

"pbd22" wrote in message @v29g2000hsf.googlegroups.com...
> Hi.
>
> Anybody know of any good code examples out there on
> how to take a telnet command and parse it?
>
> Thanks!

pbd22 · Joined: 08 Aug 2007 Posts: 5

Thanks.

I'll take a look at the ideas behind the opensource project tonight.

I don't see it being too too complicated (of course, i shouldn't count
my eggs).
The point, really, where I am having problems is this:

telnet command( "open" ) >> .net parser ( "something new").

I mean, a telnet command can be turned into a string, right?

So, if somebody remotely telnets to my computer and then
types some commands, I should be able to use TcpListener
to catch those commands and manipulate them, right?

The point where I am having problems is reading the bytestream
and translating that into a string.

Does anybody out there have some initial ideas?

Barry Kelly · Joined: 08 Aug 2007 Posts: 42

pbd22 wrote:

Telnet (AFAIK) isn't a whole lot more than a terminal emulator stuck
onto the client side of a TCP connection. And you seem to be focused on
the server side, so we can leave aside terminal control codes.

> telnet command( "open" ) >> .net parser ( "something new").
>
> I mean, a telnet command can be turned into a string, right?

The characters typed on the client end get sent over the TCP connection
pretty much literally as ASCII, yes.

> So, if somebody remotely telnets to my computer and then
> types some commands, I should be able to use TcpListener
> to catch those commands and manipulate them, right?

Yes. Create a TCP server program which listens on port 23.

> The point where I am having problems is reading the bytestream
> and translating that into a string.
> Does anybody out there have some initial ideas?

For very basic initial support, read and buffer (in a List for
example) each byte one at a time until you see a line-feed (byte value
10), then convert it into a string using Encoding.ASCII, or maybe by
manually casting the byte values into chars and stuffing into a
StringBuilder.

-- Barry

--
http://barrkel.blogspot.com/

pbd22 · Joined: 08 Aug 2007 Posts: 5

Should I be sending the

username:
password:

prompt when the user initiates the session?
There is no other way to do this, right?

I have hijacked the session so all interactivity
is coming from my program at that point, right?

If this is true, then I need to be reading from some
DB or file for access permissions, right?

Thanks.
Peter

pbd22 · Joined: 08 Aug 2007 Posts: 5

Can somebody please show me what the code would look like for sending
a
username and
password request once a telnet session is started and how to capture
that
information and parse it (if that isnt too tall a call).

Below is what I have (in a nutshell) and I am unclear what to put in
my
"TheConnectionHandler()" method. I am guessing this is where i send
user/pass request, wait for response, and parse accordingly?

I would really appreciate some help and code suggestions in the
Handler.

Thanks!

TcpClient socket;
TcpListener listener = new TcpListener(IPAddress.Any,
23);

listener.Start();

while( true)
{

socket = listener.AcceptTcpClient();
connectionQueue.Enqueue( socket);

Thread workingthread = new Thread( new
ThreadStart(TheConnectionHandler));
workingthread.Start();

}

public void TheConnectionHandler()
{

System.Net.Sockets.TcpClient socket =
(System.Net.Sockets.TcpClient)connectionQueue.Dequeue();
}

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