Telnet options in Unix

By cq_
in Linux

 Share

Recommended Posts

Experienced

cq_

Posted
Posted

So when I try to telnet to my Mac, or another unix machine (jaguar.it.miami.edu) all i get is "???? ??#??'??$" instead of a login.

(btw a standard command window will telnet just fine, just the telnet i'm using thats built into this device comes up with ???? ??#??'??$)

Has anyone seen this before? Or know of a possible fix ?

Link to comment
https://www.neowin.net/forum/topic/266206-telnet-options-in-unix/
Share on other sites
Grand Master

rezza Veteran

Posted
  • Veteran
Posted

Sounds like it might be something to do with your language settings and/or your term settings. What terminal type is the one you are using to telnet from? Is it vt100, xterm, ansi, something like that? And what language does your system use?

Basically try and be as specific as possible about the process (eg I am using an xterm on vector linux with termtype set to xterm, and using iso-8859-1 encoding, and i am using a standard telenet program to open a connection to a solaris machine with encoding set to utf8) The more info, the easier it is to help.

EDIT: just noticed you said the "telnet built into this device". What exactly is the device?

Experienced

cq_

Posted
  • Author
Posted

man I wish I knew all that stuff. The telnet is built into this contorller I'm using and I can't seem to find out the protocols it uses.

It is weird that it doesn't connect to the UNIX boxes (one is a Tru64 UNIX Version 4.0F(jaguar.it.miami.edu), and one is the Mac OS X 10.3 Unix/BSD or whatever it is)... If I telnet into a windows box, or anything other than these unix machines it works just fine...

Experienced

cq_

Posted
  • Author
Posted
  rezza said:
What exactly is this controller? Make/model number? Type of device? Other features?

585224702[/snapback]

Its an AMX NI-3000, its used for home automation/home theater component control and stuff. It's a neat box, if it would do telnet correctly... I'm calling AMX now to see if they can give me any info on thier version....

oh i changed the port from 23 to 21, and I'm able to use the ftp just fine... just not telnet...

Grand Master

rezza Veteran

Posted
  • Veteran
Posted

OK, found some specs for the ni-3000, but its still not clear what terminal type it tries to conform to, nor what language encoding it uses.

Since this only happens when telnetting, I can only guess that its to do with the way the telnet service is set up on those two machines (the miami one and the OSX one). Do you have any others you could try? In fact, could you specify port 22, and try connecting to motoreffect.ath.cx? What does that give you, more gibberish?

Experienced

cq_

Posted
  • Author
Posted

ok I found something out:

the ni-3000 doesn't use the "telnet negotiation sequence" whatever that means...

anways, ssh doesn't work, all I get is

  Quote
SSH-2.0-OpenSSH_3.9p1

Protocol mismatch.

which is exactly what happens if you do "telnet 82.14.39.112 22" in windows....

know any comands for a "negotiation sequence "?

I really apreciate this

Grand Master

rezza Veteran

Posted
  • Veteran
Posted

No, its not compatible with any telnet client, but it indicates that it can send readable characters to the client, and that's the info I was after.

Signs point to your client and the telnet servers not being compatible. Not sure what you can do about that, really...

Experienced

cq_

Posted
  • Author
Posted

converting that initial giberish to decimal gives me:

255,253,24,255,253,32,255,253,35,255,253,39,255,253,36

and if you look here: http://www.scit.wlv.ac.uk/~jphb/comms/telnet.html

there are all kinds of things:

Name	Decimal Code	Meaning
SE	240	End of subnegotiation parameters.
NOP	241	No operation
DM	242	Data mark. Indicates the position of a Synch event within the data stream. This should always be accompanied by a TCP urgent notification.
BRK	243	Break. Indicates that the "break" or "attention" key was hit.
IP	244	Suspend, interrupt or abort the process to which the NVT is connected.
AO	245	Abort output. Allows the current process to run to completion but do not send its output to the user.
AYT	246	Are you there. Send back to the NVT some visible evidence that the AYT was received.
EC	247	Erase character. The receiver should delete the last preceding undeleted character from the data stream.
EL	248	Erase line. Delete characters from the data stream back to but not including the previous CRLF.
GA	249	Go ahead. Used, under certain circumstances, to tell the other end that it can transmit.
SB	250	Subnegotiation of the indicated option follows.
WILL	251	Indicates the desire to begin performing, or confirmation that you are now performing, the indicated option.
WONT	252	Indicates the refusal to perform, or continue performing, the indicated option.
DO	253	Indicates the request that the other party perform, or confirmation that you are expecting the other party to perform, the indicated option.
DONT	254	Indicates the demand that the other party stop performing, or confirmation that you are no longer expecting the other party to perform, the indicated option.
IAC	255	Interpret as command

There are a variety of options that can be negotiated between a telnet client and server using commands at any stage during the connection. They are described in detail in separate RFCs. The following are the most important.

Decimal code	Name	RFC
1	echo	857
3	suppress go ahead	858
5	status	859
6	timing mark	860
24	terminal type	1091
31	window size	1073
32	terminal speed	1079
33	remote flow control	1372
34	linemode	1184
36	environment variables	1408

which is promising :)

Grand Master

rezza Veteran

Posted
  • Veteran
Posted
  cq107 said:
converting that initial giberish to decimal gives me:

255,253,24,255,253,32,255,253,35,255,253,39,255,253,36

and if you look here: http://www.scit.wlv.ac.uk/~jphb/comms/telnet.html

there are all kinds of things:

[snip...]

which is promising :)

585225076[/snapback]

Yes, that is promising. This thread rocks. "Today at neowin I leaned more about telnet, and the handshaking process it goes through to start a session".

Experienced

cq_

Posted
  • Author
Posted
  rezza said:
Yes, that is promising. This thread rocks. "Today at neowin I leaned more about telnet, and the handshaking process it goes through to start a session".

585225100[/snapback]

YESS1!!!!!!!!!!!!!!!!!!!!

it works... all i did was echo back each thing i got from the terminal

wait 5 SEND_STRING dvServer, "255,253,24,255,253,32,255,253,35,255,253,39,255,253,36";
    wait 10 SEND_STRING dvServer, "255,252,24,255,252,32,255,252,35,255,252,39,255,252,36";
    wait 15 SEND_STRING dvServer, "255,251,3,255,253,1,255,253,34,255,253,31,255,251,5,255,253,33";
    wait 20 SEND_STRING dvServer, "255,253,3,255,251,1,255,252,34,255,252,31,255,254,5,255,252,33";

finally i got:

login:

!!!!!!!!!!!!!!!!!!! :woot: :D

This topic is now closed to further replies.
 Share
Go to topic listing

  • Recently Browsing   0 members

    • No registered users viewing this page.