Reverse telnet failing/hangin on ...Open

[joshbgosh10592]

Hello all,

I've been searching around the Internet and many forums to try to get reverse telnet working to connect a 3640 Router to a 3550 Switch.

What I know for sure is I need a rollover cable, 8-1, 7-2, etc connected to the router's AUX and the switch's con ports. That is done.

I know that I need to have the aux port on the router configured for:

line aux 0

modem InOut

transport input all

transport output all

Tty Typ Tx/Rx A Modem Roty AccO AccI Uses Noise Overruns Int
* 0 CTY - - - - - 0 0 0/0 -
129 AUX 9600/9600 - inout - - - 0 0 0/0 -
130 VTY - - - - - 1 0 0/0 -
131 VTY - - - - - 0 0 0/0 -
132 VTY - - - - - 0 0 0/0 -
133 VTY - - - - - 0 0 0/0 -
134 VTY - - - - - 0 0 0/0 -

The weird thing is, when I get into line aux 0, nothing ever updates in show run... When I try to "no line aux 0" or even to default it, I receive "% Vty line 129 doesn't exist". To make the changes to run config, I've had to go into config t> line 129, which is atleast the line for AUX 0. When changing the config for line 129, the running config for line aux 0 does reflect.

When doing a show run:
line aux 0
modem InOut
no exec (I read that having exec on causes problems.
transport input all
transport output all

To connect, I'm trying "telnet 192.168.0.1 2129) 192.168.0.1 is my loopback. My LAN is on a 10.9.x.x\16 scheme.
I'm returned with:

BurgerRouter#telnet 192.168.0.1 2129
Trying 192.168.0.1, 2129 ... Open

And then the line freeze and cannot be cleared unless I connect to it using the other means (for example, if I start the telnet to switch from Console, I have to telnet into it to run a clear line 129, which then freeze up the other console).

What are your thoughts?

[acampbell]

Hi,

I think your problem is the config on the aux port.

You have :-

!
line aux 0
 modem InOut
!

This means your "aux port" is waiting for a cts signal from the attached device like a modem etc.
The switch "console port" does not send or receive rts/cts

Try reconfiguring your aux port.

!
line aux 0
no modem InOut
!

Retest and let us know how you get on.

Regards
Alex

[joshbgosh10592]

Hi Alex,

Same problem after testing.

Config

line aux 0
no exec
transport input all
transport output all

Results:

BurgerRouter#telnet 192.168.0.1 2129
Trying 192.168.0.1, 2129 ... Open

[Richard Bradfield]

You need the "exec" command

line aux 0

exec

when you do a sh runn command you wont see the "exec" command as that is the default value

HTH

Richard

[joshbgosh10592]

Hi Richard,

I put that command back in, so my current config is:

line aux 0
transport input all
transport output all

And it still hands on ... Open.

[Richard Bradfield]

Hi Josh,

just thinking the config looks good, so could it be your crossover cable, are you using the Cisco light blue ribbon cable? Have you any other router you could test it on incase the AUX port of the 3640 is stuffed? or the console port of the switch, have you connected to the console port of the switch from a PC ?

just a few thoughts

regards

Richard.

[joshbgosh10592]

I'm using a custom made rollover cable, 8-1, 7-2, etc. I actually just verified the cable with a tester, and all 8 wires are reversed, so it tests good.

Maybe there needs to be a config on the console port on the switch? I just don't understand how this isn't working. I would be using IP 2129, right? 2000+ the line number?

[Richard Bradfield]

Yes 2129 is right. Have you a cable for connecting your PC to the console port of the 3640? if so you should also be able to use it to connect to the Aux port to check it out. I suspect the physical aux port on 3640 or console port on the switch.

[joshbgosh10592]

I know that th console port on the switch is good (I actually used it last night to check the settings on the switch).

So I'd connect the cable from the Router's Aux to a PC? How would I verify that? Would the router accept an incoming connection on the aux?

[Richard Bradfield]

once the router is up and running you can connect to the Aux port the same as the console port.

[joshbgosh10592]

Welp, I just connected my console cable into the aux port, and I'm in. Just to make sure...

BurgerRouter#sho line
Tty Typ Tx/Rx A Modem Roty AccO AccI Uses Noise Overruns Int
* 0 CTY - - - - - 1 0 0/0 -
* 129 AUX 9600/9600 - - - - - 1 0 0/0 -
130 VTY - - - - - 1 0 0/0 -
131 VTY - - - - - 0 0 0/0 -
132 VTY - - - - - 0 0 0/0 -
133 VTY - - - - - 0 0 0/0 -
134 VTY - - - - - 0 0 0/0 -

Line(s) not in async mode -or- with no hardware support:
1-128

BurgerRouter#sho users
Line User Host(s) Idle Location
0 con 0 idle 03:15:18
*129 aux 0 idle 00:00:00

I'm at a loss.. This confirms the aux port works, I know for a fact that the switch's console port works, I verified the cable is in fact a full rollover cable (8-1, 7-2, 6-3, 5-4, etc) and all wires show connectivity in my tester.

[Richard Bradfield]

Yes that proves the Aux port configured ok

have you a username/password setup for the router.

might need something like 

username Cisco priv 15 password cisco123

aaa authentication login default local

so then when you telnet to 192.168.0.1 2129 you should get a username and password prompt, after you enter the router username password, you shou;d then get a login prompt from the switch.

[joshbgosh10592]

I added exactly the username command you provided, but before I put the second line "aaa authentication login default local", I had to run "aaa new" first.

I ran the telnet command "telnet 192.168.0.1 2129" Logged in using the credentials in the first command, and hung after hitting enter after the password.

Also, thank you for your input on my other issue posted.

[Richard Bradfield]

This really puzzleing, its as if you have no connection at all,

I know most new routers have line 1 as the Aux port, so what happens if you try and connect to 192.168.0.1 2001? most probably be rejected!

[joshbgosh10592]

After I commented, I realized that I had forgotten to move the cable back, so that last test was invalid...

I didn't commit the two commands you posted above to start-config, and reloaded the router last night. I corrected the cabling, and tried both ports, 2129 and 2001, both did fail - %Connection refused by remote host.

Just to see if maybe we're missing something, here's a dump of the current running config.

Router#sho run
Building configuration...

Current configuration : 1511 bytes
!
version 12.4
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname Router
!
boot-start-marker
boot-end-marker
!
enable secret 5 $1$yvku$3ExvHb9Jf6R4Ka9WXT7bP0
enable password password
!
aaa new-model
!
!
aaa authentication login default local
!
aaa session-id common
!
!
ip cef
!
username Cisco privilege 15 password 0 cisco123
!
interface Loopback0
no ip address
!
interface Ethernet0/0
description Uplink
ip address 10.9.0.160 255.255.0.0
half-duplex
no mop enabled
!
interface Ethernet0/1
description To MDF
ip address 192.168.0.1 255.255.255.0
half-duplex
!
interface Ethernet1/0
no ip address
shutdown
half-duplex
no cdp enable
!
interface Ethernet1/1
no ip address
shutdown
half-duplex
no cdp enable
!
interface Serial3/0
no ip address
shutdown
!
interface Serial3/1
no ip address
shutdown
no cdp enable
!
interface Serial3/2
no ip address
shutdown
no cdp enable
!
interface Serial3/3
no ip address
shutdown
no cdp enable
!
ip default-gateway 10.9.0.1
ip http server
no ip http secure-server
ip route 0.0.0.0 0.0.0.0 10.9.0.1
ip route 0.0.0.0 0.0.0.0 Ethernet0/0 10.9.0.1
!
control-plane
!
line con 0
exec-timeout 0 0
password password
transport output all
line aux 0
transport input all
transport output all
line vty 0 4
password Password0
!
no process cpu extended
no process cpu autoprofile hog
!
end

Switch:

MDF1#sho run
Building configuration...

Current configuration : 6026 bytes
!
version 12.2
no service pad
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname MDF1
!
enable secret 5 $1$b3s.$uzzAh3l2xwzNc2UNJAIuc1
enable password LINE
!
username Josh password 0 Password0
aaa new-model
!
!
aaa authentication enable default group word none
!
!
!
aaa session-id common
clock timezone EST -5
clock summer-time EDT recurring 1 Sun Mar 2:00 last Sun Oct 2:00
ip subnet-zero
ip domain-name name.local
ip name-server 10.9.0.1
!
!
!
crypto pki trustpoint TP-self-signed-2413871872
enrollment selfsigned
subject-name cn=IOS-Self-Signed-Certificate-2413871872
revocation-check none
rsakeypair TP-self-signed-2413871872
!
!
crypto pki certificate chain TP-self-signed-2413871872
certificate self-signed 01 [STRING]
quit
!
!
spanning-tree mode pvst
spanning-tree extend system-id
!
vlan internal allocation policy ascending
!
ip ssh authentication-retries 5
ip ssh version 2
!
!

[ALL Fa/Gi PORTS]

interface Vlan1
ip address 192.168.0.2 255.255.255.0
!
interface Vlan2
ip address 192.168.58.120 255.255.255.0
!
ip default-gateway 10.9.0.160
ip classless
ip http server
ip http secure-server
!
!
control-plane
!
!
line con 0
line vty 0 4
transport input ssh
line vty 5 15
!
ntp clock-period 17180366
ntp server 206.246.122.250
ntp server 131.107.13.100
ntp server 129.6.15.30
ntp server 129.6.15.28
end