Telnetlib get unreadable character while cygwin or putty not

I found a strange problem with python's telnetlib module. When I use the telnetlib to access a server and try to get the information, it always show some strange character, and I am sure its not the encoding problem, the output just like below:

1[2J[3;1HPort Type       IP1             IP2             IP3             IP4[4;1H 01  Real COM  [5;1H 02  Real COM  [6;1H 03  Real COM  [7;1H 04  Real COM  [8;1H 05  Real COM  [9;1H 06  Real COM  [10;1H 07  Real COM  [11;1H 08  Real COM  [12;1H 09  Real COM  [13;1H 10  Real COM  [14;1H 11  Real COM  [15;1H 12  Real COM  [16;1H 13  Real COM  [17;1H 14  Real COM  [18;1H 15  Real COM  [19;1H 16  Real COM  [20;1H

But when I use some shell-like applications to telnet to the server, what I get is quite good and neat, there are no strange characters. Below is the result that I got using cygwin:

Port Type       IP1             IP2             IP3             IP4
01  Real COM   Listen
02  Real COM   Listen
03  Real COM   147.128.14.147
04  Real COM   Listen
05  Real COM   Listen
06  Real COM   Listen
07  Real COM   Listen
08  Real COM   Listen
09  Real COM   Listen
10  Real COM   Listen
11  Real COM   Listen
12  Real COM   Listen
13  Real COM   Listen
14  Real COM   Listen
15  Real COM   Listen
16  Real COM   Listen

Has anyone met the same problem? And why does this happen? How can I get a "neat" result when I use telnetlib?

Below is the simple script:

import telnetlib
if __name__ == '__main__':
    HOST = '10.185.20.2'
    tn = telnetlib.Telnet(HOST)
    r1 = tn.read_until('selection: ', 5)
    print r1
    tn.write('8' + '\r\n')
    r2 = tn.read_until('selection: ', 5)
    print r2
    tn.write('1 ' + '\r\n')
    r3 = tn.read_until('cancel ...', 5)
    print r3

Solution

Those look a lot like terminal escape sequences, with the escape byte (0x1b) missing. In many terminals, certain sequences of bytes have special effects, such as changing the color, moving the cursor, etc. For example, \x1b[3;1H means "move the cursor to row 3, column 1" on VT100 or compatible terminals, which most terminals are. (The VT100 is long dead, but many terminal applications such as Terminal.app, GNOME Terminal, and xterm, still use those escape sequences.)

You might be getting the escape byte (0x1b), but it's being filtered somehow. repr helps here, as it shows you what is actually in your string. You can get a list of common escape sequences, too.