Telnet TC6.0

[soohyung choi]

Hi

We must maintain codec using telnet

Before upgrading to TC6.0, connected codec using telnet.

But After upgrading to TC6.0, cannot

Message:
getnameinfo: localhost: Success
                               Temporary failure in name resolution: Success

(don't have name server)

we need name server necessarily for using telnet?

or What's another method ?

Thanks for your help always

[hashimoto.kotaro · Accepted solution]

Hi Soohyung,

I confirmed the issue happned on our EX60, too.

It seems that the misconfiguration of TC6.0 OS causes this.

I guess we must wait for Cisco releases TC6.0.1.

Anyway, we can use SSH instead, as a workaround.

Kotaro Hashimoto

[Danny De Ridder]

Hello,

I checked TC6.0.1 on our C40 here in Brussels and I see that the codec does a so-called reverse DNS lookup for the host which is connecting to the codec.

In my case, the IP address of the codec is 144.254.13.69 and the unix system which tries to connect has IP address

144.254.10.208. When I do telnet to the codec I see following DNS messages :

Time                Source                Destination           Protocol Length Info

2010-01-27 08:13:29 144.254.13.69         144.254.71.184        DNS      87     Standard query PTR 208.10.254.144.in-addr.arpa

2010-01-27 08:13:29 144.254.71.184        144.254.13.69         DNS      191    Standard query response PTR sweet-brew-7.cisco.com

2010-01-27 08:13:29 144.254.13.69         144.254.71.184        DNS      82     Standard query A sweet-brew-7.cisco.com

2010-01-27 08:13:29 144.254.13.69         144.254.71.184        DNS      82     Standard query AAAA sweet-brew-7.cisco.com

2010-01-27 08:13:29 144.254.71.184        144.254.13.69         DNS      166    Standard query response A 144.254.10.208

2010-01-27 08:13:29 144.254.71.184        144.254.13.69         DNS      142    Standard query response

In linux these lookups can be turned off, but the codec file system will be rebuilt after reload so we would lose any changes. Let me ask in our meeting with escalation whether this can be turned off.

[Martin Koch]

I just tried it on my ex90/tc6 and telnet works fine when DNS is reachable (I have reverse

entries configured) and it does not work if I block the lookup with the same error message.

The ssh connection takes much longer to connect, but at least it works without DNS.

Workarounds could be:

* use ssh (anyhow recommended, what is stopping you to do so? Only reason I see would be the TCNC sw)

* use the webinterface

* properly configure DNS (also recommended :-)

* add the remote hosts ip and name in /etc/hosts

* disable the lookup which locks it

* if its defined as a bug (and not for example as a security features): wait for a upgrade

* possible more

Danny: I would say the workaround could be to add a startup script adding the entry to the hosts file or to

disable the lookup, how / on which level would you do that? os-level, nnswitch, xinetd, telnetd?

[Danny De Ridder]

I think the things are set at xinetd level.

[hdewulf-c40:/etc/xinetd.d] $ pwd

/etc/xinetd.d

[hdewulf-c40:/etc/xinetd.d] $ cat telnet

service telnet

{

    disable     = no

    id          = telnet

    socket_type = stream

    wait        = no

    flags       = REUSE IPv6

    user        = root

    group       = root

    server      = /extra/sbin/in.telnetd

}

[hdewulf-c40:/etc/xinetd.d] $

When I block my traffic to my DNS servers I learnt via DHCP I get my telnet closed indeed.

sweet-brew-7:/home/dderidde # telnet 144.254.13.69

Trying 144.254.13.69...

Connected to 144.254.13.69.

Escape character is '^]'.

getnameinfo: localhost: Success

Temporary failure in name resolution: Success

Connection to 144.254.13.69 closed by foreign host.

sweet-brew-7:/home/dderidde #

Let me raise the question on our weekly call we have with the TelePresence business unit.

[hdewulf]

It's reported via CSCue72551    TC6.0.0.876266: Telneting to EX90/C90 failed .

/Hans

[garryemiller]

Hi Danny,

Any movement on this issue? Thanks in advance

[Danny De Ridder]

Hello,

the root cause of the problem has been fixed. It's now a matter of waiting for released code with the fix integrated. I have no release schedule for TC6.x release(s), so cannot comment on ETA of the release.

[pnorman74]

Our client reset their codec and Dns was not set in the static address setup on the SX20. Set the Dns and the issue was resolved. Thank you all for the info!