Python Telnet formatting?

[mentaltruckdriver]

Hi everyone:

I posted here a couple days ago looking for some help creating a
Telnet-based chat server. You guys pointed me to Twisted, which has
solved most of my issues.

However, what I want to do is analyze strings received for keywords
such as 'listcmds' and have the server return something to the client.
I know how to do that part, at least.

The issue is, when I use clients like PuTTY, it returns a lot of what
appears to be formatting (e.g. if I typed Hello, it would return "\xff
\xfb\x1f\xff\
xfb \xff\xfb\x18\xff\xfb'\xff\xfd\x01\xff\xfb\x03\xff\xfd\x03Hello".)

How would I go about filtering this stuff out of the strings? The
thing is too, if I use other Telnet programs like Microsoft Telnet,
they don't have this formatting, so I want to be able to recognize if
it does have this formatting and act based on if it does or if it
doesn't.

Any help is appreciated, I know I'm probably asking too many questions
already

Thanks everyone.

 

[Gabriel Genellina]

Hi everyone:

I posted here a couple days ago looking for some help creating a
Telnet-based chat server. You guys pointed me to Twisted, which has
solved most of my issues.

However, what I want to do is analyze strings received for keywords
such as 'listcmds' and have the server return something to the client.
I know how to do that part, at least.

The issue is, when I use clients like PuTTY, it returns a lot of what
appears to be formatting (e.g. if I typed Hello, it would return "\xff
\xfb\x1f\xff\
xfb \xff\xfb\x18\xff\xfb'\xff\xfd\x01\xff\xfb\x03\xff\xfd\x03Hello".)

They are part of the telnet protocol; 0xFF (IAC=Interpret as Command)
starts a two or three byte command sequence.
Weren't you using telnetlib? It's supposed to handle this transparently.

How would I go about filtering this stuff out of the strings? The
thing is too, if I use other Telnet programs like Microsoft Telnet,
they don't have this formatting, so I want to be able to recognize if
it does have this formatting and act based on if it does or if it
doesn't.

Any client could send similar commands at the start of the session, or
even later.

Any help is appreciated, I know I'm probably asking too many questions
already

It isn't too hard to filter them out, if you want to do it by hand. See
the source for telnetlib, and the original Telnet specificacion, RFC 854
http://www.rfc-archive.org/getrfc.php?rfc=854 and RFC 855.

 

[Gabriel Genellina]

Hi everyone:

I posted here a couple days ago looking for some help creating a
Telnet-based chat server. You guys pointed me to Twisted, which has
solved most of my issues.

However, what I want to do is analyze strings received for keywords
such as 'listcmds' and have the server return something to the client.
I know how to do that part, at least.

The issue is, when I use clients like PuTTY, it returns a lot of what
appears to be formatting (e.g. if I typed Hello, it would return "\xff
\xfb\x1f\xff\
xfb \xff\xfb\x18\xff\xfb'\xff\xfd\x01\xff\xfb\x03\xff\xfd\x03Hello".)

They are part of the telnet protocol; 0xFF (IAC=Interpret as Command)
starts a two or three byte command sequence.
Weren't you using telnetlib? It's supposed to handle this transparently.

How would I go about filtering this stuff out of the strings? The
thing is too, if I use other Telnet programs like Microsoft Telnet,
they don't have this formatting, so I want to be able to recognize if
it does have this formatting and act based on if it does or if it
doesn't.

Any client could send similar commands at the start of the session, or
even later.

Any help is appreciated, I know I'm probably asking too many questions
already

It isn't too hard to filter them out, if you want to do it by hand. See
the source for telnetlib, and the original Telnet specificacion, RFC 854
http://www.rfc-archive.org/getrfc.php?rfc=854 and RFC 855.

 

[Bjoern Schliessmann]

They are part of the telnet protocol; 0xFF (IAC=Interpret as
Command) starts a two or three byte command sequence.
Weren't you using telnetlib? It's supposed to handle this
transparently.

With Twisted you don't need Telnetlib, twisted.conch.telnet does the
job. I would definitely look at twisted.words, too.

Regards,


Björn

 

[Grant Edwards]

I posted here a couple days ago looking for some help creating
a Telnet-based chat server. You guys pointed me to Twisted,
which has solved most of my issues.

And we told you that you needed to implement the telnet protocol.

The issue is, when I use clients like PuTTY, it returns a lot
of what appears to be formatting (e.g. if I typed Hello, it
would return "\xff \xfb\x1f\xff\
xfb\xff\xfb\x18\xff\xfb'\xff\xfd\x01\xff\xfb\x03\xff\xfd\x03Hello".)

That "stuff" that you call "formatting" are commands for the
telnet protocol. Apparently you've ignored what I told you
about implementing the telnet protocol (or using something that
does).

How would I go about filtering this stuff out of the strings?

Once again: If you're trying to write a telnet server, you
need to implement the telnet protocol.

The thing is too, if I use other Telnet programs like
Microsoft Telnet, they don't have this formatting,

Different telnet clients act a little differently. Some won't
try to negotiate with the tenlet server until the server starts
the negotiation.

so I want to be able to recognize if it does have this
formatting and act based on if it does or if it doesn't.

You have to handle the telnet protocol if you want to talk to
telnet clients.