[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: /dev/tcp telnet negotiation

From: Illia Bobyr
Subject: Re: /dev/tcp telnet negotiation
Date: Fri, 29 Apr 2011 10:51:39 -0500
User-agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv: Gecko/20110414 Lightning/1.0b3pre Mnenhy/0.8.3 Thunderbird/3.1.10

On 4/28/2011 7:09 AM, Allan Pinto wrote:

i run a lot telnet scripts using /dev/tcp for cisco routers, lately we
have newer models of cisco routers which have ios-xr which is based on
linux and also some mikrotik routers which are again based on linux,
on these devices when i run my script all i get is  ÿý^Xÿý
ÿý#ÿý'ÿý$ÿý! in my output, no username prompt, on the same device if
if use a netcat -T option which is for telnet negotiation, it works,
Could anyone guide me in the right direction where i can achieve the
same using /dev/tcp
below example script


exec 3<>/dev/tcp/$1/23
sleep 1
echo -e "username">&3
echo -e "password">&3
echo -e "sh ver">&3
#sleep 2
echo -e "logout">&3
cat<&3 > $1.txt


Telnet is not just a pipe.  It is a real protocol.  Though, rather a simple one.
What you see is a telnet options negotiation.
See http://www.faqs.org/rfcs/rfc854.html for details.

Ilya Bobyr

reply via email to

[Prev in Thread] Current Thread [Next in Thread]