[Net-Telnet] Line feed problems with login

[Adam Stuckey <ad...@marconi.com.au>]

Hi All,

I am having a strange problem when trying to log into a remote system via
telnet.
My code works when logging into a Sun Solaris or HP-UX machine, but fails
when connecting to a particular device (a type of modem).
When I send the username, I append a "\r" to the end.  The remote device
immediately responds with "Invalid Password", before even asking my program
to enter the password.  I have ran an ethereal packet trace of what is
happening, and it appears that when I send "username\r", "username\r\n" is
actually sent to the remote system.  The remote system interprets this as
two enter presses, and believes a blank password was entered. Similarly, if
I send "username\n", "username\r\n" is actually sent to the remote node,
causing the same issue.
Is there a way to either prevent this additional "\n" being appended?  I am
using the out.write( byte ) method rather than out.writeln( byte[] ) so I
don't know where the additional "\n" is coming from.

Regards,
Adam


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Re: [Net-Telnet] Line feed problems with login

[SOMOGYI Erzsebet <rz...@impulzus.sch.bme.hu>]

Hi!

Adam Stuckey wrote:
> Is there a way to either prevent this additional "\n" being appended?  I am
> using the out.write( byte ) method rather than out.writeln( byte[] ) so I
> don't know where the additional "\n" is coming from.

I also had some \r\n problems. TelnetClient always sends \r\n as end of 
line and doesn't care if you tries to send only \r or \n.

Conversion is done in org.apache.commons.net.TelnetOutputStream in 
write(int ch) _and_ in org.apache.commons.io.ToNetASCIIOutputStream in 
write(int ch). Output stream of TelnetClient is a ToNetASCIIOutputStream 
which is initialized with a TelnetOutputStream (see _connectAction_() of 
TelnetClient).

You could try  set __convertCRtoCRLF in TelnetOutputStream to false or 
modify write method, and modify write method of ToNetASCIIOutputStream.

Finally I solved my problem on server side instead of modifing the 
source codes, so I'm not sure about this solution.

Regards,
  Rzso

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