Help: hex encode contents of secret cookie and pass on to a program via. bash?

[jeffs]

Hello,

I need to encode the contents of a secret cookie (Tor) with hex and use that to AUTHENTICATE a telnet session. I do not know how to do this and I was hoping someone could assist me or get me going in the right direction.

Here's the signal script:

telnet 127.0.0.1 9051
Escape character is '^]'.
AUTHENTICATE <Hexed_Cookie_Contents_Here>
250 OK
signal NEWNYM
250 OK
quit

thank you

[wje_lf]

Read the top part of this.

Hope this helps.

[jeffs]

Hi wje_lf,

Thank you for the link, it confirmed my assumptions. I wrote a couple of lines to try and automate the process but as I'm fairly new to bash scripting I did not get it right...I'm still trying to figure it out by trail and error. (I didn't add any exit codes, etc, yet as I wanted to make it work first.)

Would you mind looking over these lines? I'm pretty sure I did not write the variable with CAT correctly, nor the use of the variable with AUTHENTICATE.

cd ~/.tor
# http://www.warpspeed.com.au/Products/OS2/GU/Manual/hexdump.htm
hexdump control_auth_cookie >>hex_cookie_output.txt

# Set variable of magic cookie hex dump using CAT
HEX_COOKIE="cat $hex_cookie_output.txt"

telnet 127.0.0.1 9051	
# Is the following line needed?
Escape character is '^]'.
# Use magic cookie hex dump variable w/authenticate
AUTHENTICATE "HEX_COOKIE"
250 OK
signal NEWNYM
250 OK
quit

Another issue is that 'hexdump' has an output like:

0000000 fce4 cb66 1640 d895 9a5b f12c 3ed6 c075
0000010 d4dc c325 4dc7 b33b b82c 02cd e08b c752
0000020

...and Tor expects the following hex format with AUTHENTICATE. Should I use a different hex dumping tool? Is there a command or app to remove white space, etc, from 'hexdump' output?

AUTHENTICATE ee10875cb04a837374918510d75ff600f85abc04a33fda23895954dcd69a6a3b

Thank you!

[wje_lf]

You can solve all your hex dumping problems thus:

HEX_COOKIE=$(echo $(hexdump control_auth_cookie | sed -e 's/^.......//') | sed -e 's/ //g')

Your next problem will be finding a way to feed that to telnet. A simple answer here cannot instruct you fully in that. I recommend you do this at the command line:

man expect

expect is a program which lets you write scripts which simulate typing keys (as in, typing info to telnet) and reading responses.

[jeffs]

Hi,

thank you for that code, I have much to learn. I will read the manual of expect.