telnet 0

[Shahril M]

Hi,

This command opens a new session to the current host. However, I have ever encountered boxes which do not recognise the 0 (zero) parameter.

Can someone share with me where this is configured?


Rgds,
Shahril

[harry d brown jr]

What kind of boxes would that be? Could you tell us the OS, patch level, bit level, hareware model? Security settings? applications?

live free or die
harry

[Wodisch]

Hi,

I used to use "telnet ." on HPUX10.20 and 11.0, but it seems to not work any more on HPUX11i :-(
...and not on S(l)olaris 7/8 and not on linux...

FWIW,
Wodisch

[John Palmer]

It's down to the way that IP name resolution has been implemented, I doubt very much that you'd be able to configure it.

If you try ping 0 or . or .. or ... you'll see a response from 127.0.0.1 the loopback address.

Personally, I wouldn't worry about it - if typing 'telnet localhost' is too much trouble, add a single character hostname as an alias to localhost and use that.

Regards,
John

[Deshpande Prashant]

Hi
Recently I have upgraded couple of my boxes to 11i from 11.0 to find telnet 0 won't work on 11i.

Thanks
Prashant.

[Scott Van Kalken]

I'm not 100% sure (so essentially what I'm saying is that this is pure speculation)

but I should think that the implementation of route.h may have changed.

[Kellogg Unix Team]

Prashant,

We have 11i servers and 'telnet 0' works just fine. We did a fresh install on them.

sysA # uname -a
HP-UX sysA B.11.11 U 9000/800 142575636 unlimited-user license
sysA # telnet 0
Trying...
Connected to 0.
Escape character is '^]'.
Local flow control on
Telnet TERMINAL-SPEED option ON

HP-UX sysA B.11.11 U 9000/800 (te)

login:

...Manjeet

[Kellogg Unix Team]

Shahril,

How does your /etc/hosts look like? Does it have an entry for localhost?

Also, are you making use of /var/adm/inetd.sec file? If yes, can you post telnet-related entries?

Rgds
...Manjeet

[Shahril M]

Hi John,

I just want to learn how it is configured.

Hi Manjeet,

My /etc/hosts is normal:
127.0.0.1 localhost loopback
followed by the various machine entries

And, no, I am not using inetd.sec.


Rgds,
Shahril

[Kellogg Unix Team]

Shahril,

Looking at the responses so far (and checking for 11i myself), I don't see problem to be an OS limitation. When you say you are unable to "telnet 0" for some servers, were you -

1. able to do "telnet localhost" successfully?
2. ping 0 (as suggested by John) successfully?
3. telnet to the server (as opposed to remsh)?

I vaguely remember seeing this problem somewhere. If you can post more details viz. under what circumstances you see this problem, that will help.

Rgds
...Manjeet

[Shahril M]

Hi Manjeet,

I think I have led you astray. All my machines allow telnet 0, but those at the HP classrooms when I go for training do not.

I had asked my instructor, but he does not know.

As I have told John, this is just for learning's sake.

Nevertheless, appreciate if someone can still assist in figuring this out. Knowledge and points up for grabs.


TIA,
Shahril

[U.SivaKumar_2]

Hi,

It will work on HP-UX 10.X But not working in HP-UX 11.x . Nothing to do with /etc/hosts .

Some hardcoded thing in telnet executable.

regards,
U.SivaKumar

[sven verhaegen]

Hello


I did some tests on the 11.i implementation of HP-UX , we've got several servers running on several patchlevels so I had the chance of testing it several times, these are my results ..

the telnet 0 should work as before , indeed the procedure works by redirecting you to the 127.0.0.1 loopback interface , the only way it could fail is if in the routing does go horribly wrong , testing the loopback with nslookup isn't ok as it would return an error on 0 but when doing ping 0 you should see the 127.0.0.1 interface been pinged , it could however be that someone has made changes on your system so that this feature doesn't work or that some errors have crept into the DNS implementation (or that the system has no patching at all , all my systems do run at least a telnet and an arpa transport patch)

the only way to fix this would be to see if indeed something is wrong with the name resolving as this is the most probable cause of the 'problem/behaviour" you see at the HP classroom environment

if this doesn't help could you be more specific to what reply telnet gives , is it a simple hostname unknown or a more elaborate message or error code