From: Thomwin Chen (thomwin_chen@yahoo.com)
Date: Thu Sep 28 2006 - 03:36:46 ART
Hi Dave,
actually reverse telnet doesn't do anything with Telneting to another router.
it is just the connection made via the router's TTY to another router's console, this way we can reach another router's console connected to the TTY line.
TerminalServer#show host
Default domain is not set
Name/address lookup uses static mappings
Codes: UN - unknown, EX - expired, OK - OK, ?? - revalidate
temp - temporary, perm - permanent
NA - Not Applicable None - Not defined
Host Port Flags Age Type Address(es)
BB1 2065 (perm, OK) 0 IP 1.1.1.1
SW1 2074 (perm, OK) 0 IP 1.1.1.1
SW2 2075 (perm, OK) 0 IP 1.1.1.1
PIX 2076 (perm, OK) 0 IP 1.1.1.1
R4 2069 (perm, OK) 0 IP 1.1.1.1
R2 2067 (perm, OK) 0 IP 1.1.1.1
R3 2068 (perm, OK) 0 IP 1.1.1.1
R1 2066 (perm, OK) 0 IP 1.1.1.1
R6 2071 (perm, OK) 0 IP 1.1.1.1
R5 2070 (perm, OK) 0 IP 1.1.1.1
BB2 2072 (perm, OK) 49 IP 1.1.1.1
BB3 2073 (perm, OK) ** IP 1.1.1.1
TerminalServer#show line
Tty Typ Tx/Rx A Modem Roty AccO AccI Uses Noise Overruns Int
0 CTY - - - - - 10 0 0/0 -
* 65 TTY 9600/9600 - - - - - 5 16 0/0 -
* 66 TTY 9600/9600 - - - - - 38 5181 0/0 -
67 TTY 9600/9600 - - - - - 16 21262 0/0 -
* 68 TTY 9600/9600 - - - - - 41 42578 0/0 -
* 69 TTY 9600/9600 - - - - - 25 3165 0/0 -
* 70 TTY 9600/9600 - - - - - 28 208 0/0 -
* 71 TTY 9600/9600 - - - - - 21 59258 0/0 -
72 TTY 9600/9600 - - - - - 5 268756 0/0 -
73 TTY 9600/9600 - - - - - 0 0 0/0 -
* 74 TTY 9600/9600 - - - - - 20 1555 20515/61650 -
* 75 TTY 9600/9600 - - - - - 26 1926 3199/9635 -
* 76 TTY 9600/9600 - - - - - 19 122 0/0 -
77 TTY 9600/9600 - - - - - 0 0 0/0 -
78 TTY 9600/9600 - - - - - 0 0 0/0 -
79 TTY 9600/9600 - - - - - 0 0 0/0 -
80 TTY 9600/9600 - - - - - 0 0 0/0 -
129 AUX 115200/115200- inout - - - 42 0 1837/0 -
* 130 VTY - - - - - 263 0 0/0 -
* 131 VTY - - - - - 92 0 0/0 -
132 VTY - - - - - 3 0 0/0 -
133 VTY - - - - - 0 0 0/0 -
134 VTY - - - - - 0 0 0/0 -
the asterisk (*) means that the line is currently being used.
in this example, reverse telneting to R3 (Port 2068, line 68) will fail because the line is currently being used.
TerminalServer#R3
Trying R3 (1.1.1.1, 2068)...
% Connection refused by remote host
and reverse telneting to BB2 (Port 2072, line 72) will succeed because the line is currently available.
TerminalServer#BB2
Trying BB2 (1.1.1.1, 2072)... Open
User Access Verification
Username: tom
Password:
if you issue show tcp brief on the terminal server, the output will be something like this :
BB2#
TerminalServer#show tcp brief
TCB Local Address Foreign Address (state)
61DBBC6C 1.1.1.1.32387 1.1.1.1.2072 ESTAB
61DBCC34 1.1.1.1.2072 1.1.1.1.32387 ESTAB
from the output, we can see that the Foreign Address is the Terminal Server router itself.
if you plan to build a terminal server you can use NM-8A, NM-16A on new platform or using the old 2511 router.
TerminalServer#show diag
Slot 2:
Async Port adapter, 16 ports
Port adapter is analyzed
Port adapter insertion time unknown
EEPROM contents at hardware discovery:
Hardware revision 0.1 Board revision L0
Serial number 33541801 Part number 800-02244-05
FRU Part Number: NM-16A=
Test history 0x0 RMA number 00-00-00
EEPROM format version 1
EEPROM contents (hex):
0x20: 01 62 00 01 01 FF CE A9 50 08 C4 05 00 00 00 00
0x30: A8 00 00 00 05 05 06 00 FF FF FF FF FF FF FF FF
HTH and CMIIW
thanks
Rgds,
Thomwin
"Schulz, Dave" <DSchulz@dpsciences.com> wrote:
I am unable to get the following reverse telnet to work .....
R1 has the following set up on the vty....
!
!
line con 0
line aux 0
line vty 0 4
privilege level 15
password cisco
login
rotary 1
!
R1(config)#do sh line
Tty Typ Tx/Rx A Modem Roty AccO AccI Uses Noise Overruns
Int
* 0 CTY - - - - - 4 407 0/0
-
129 AUX 9600/9600 - - - - - 0 0 0/0
-
130 VTY - - 1 - - 1 0 0/0
-
131 VTY - - 1 - - 0 0 0/0
-
132 VTY - - 1 - - 0 0 0/0
-
133 VTY - - 1 - - 0 0 0/0
-
134 VTY - - 1 - - 0 0 0/0
-
On R3.... I am trying to telnet to the first vty port (or any of them).
This is the response:
R3#
R3#telnet 172.16.1.1 2130
Trying 172.16.1.1, 2130 ...
% Connection refused by remote host
R3#
However, telnetting in to the unit without selecting the port works
fine. Any thoughts?
Dave Schulz,
Email: dschulz@dpsciences.com
This archive was generated by hypermail 2.1.4 : Sun Oct 01 2006 - 16:55:41 ART