Telnet IPv6 address

ashok.g · 07-22-2010, 08:07 AM

Hey I have a problem connecting to a IPv6 address via telnet on port 23.
Here is the some useful command output which describe my problem.

Code:

[root@station181 ~]# telnet 2001:db8:0:f101::1
Trying 2001:db8:0:f101::1...
telnet: connect to address 2001:db8:0:f101::1: Connection refused
telnet: Unable to connect to remote host: Connection refused

Code:

[root@station181 ~]# telnet 2001:db8:0:f101::1 80
Trying 2001:db8:0:f101::1...
Connected to stationip6 (2001:db8:0:f101::1).
Escape character is '^]'.
get
<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">
<html><head>
<title>501 Method Not Implemented</title>
</head><body>
<h1>Method Not Implemented</h1>
<p>get to / not supported.<br />
</p>
<hr>
<address>Apache/2.0.52 (Red Hat) Server at localhost.localdomain Port 80</address>
</body></html>
Connection closed by foreign host.

Code:

[root@station181 ~]# nmap -6 2001:db8:0:f101::1

Starting nmap 3.70 ( http://www.insecure.org/nmap/ ) at 2010-07-23 04:43 IST
Interesting ports on stationip6 (2001:db8:0:f101::1):
(The 1657 ports scanned but not shown below are in state: closed)
PORT    STATE SERVICE
22/tcp  open  ssh
80/tcp  open  http
443/tcp open  https

Nmap run completed -- 1 IP address (1 host up) scanned in 0.286 seconds

Code:

[root@station181 ~]# nmap 192.168.1.181

Starting nmap 3.70 ( http://www.insecure.org/nmap/ ) at 2010-07-23 04:43 IST
Interesting ports on 192.168.1.181:
(The 1652 ports scanned but not shown below are in state: closed)
PORT     STATE SERVICE
22/tcp   open  ssh
23/tcp   open  telnet
80/tcp   open  http
111/tcp  open  rpcbind
113/tcp  open  auth
199/tcp  open  smux
443/tcp  open  https
3306/tcp open  mysql

Nmap run completed -- 1 IP address (1 host up) scanned in 0.617 seconds

Please assist me.

Thanks in advance,

AlucardZero · 07-22-2010, 08:11 AM

Are 2001:db8:0:f101::1 and 192.168.1.181 the same machine or something?

If so, telnet just isn't listening on ipv6. Make it do that.

ashok.g · 07-22-2010, 10:00 AM

Quote:

Originally Posted by AlucardZero

Are 2001:db8:0:f101::1 and 192.168.1.181 the same machine or something?

Yes. They are on the same machine.

Quote:

Originally Posted by AlucardZero

If so, telnet just isn't listening on ipv6. Make it do that.

This is for what exactly I made this post.

TB0ne · 07-22-2010, 11:15 AM

Quote:

Originally Posted by ashok.g

Yes. They are on the same machine.

This is for what exactly I made this post.

How about telling us what version/distro of Linux you're using??

And from your first post, telnet isn't showing up in nmap, so it's no surprise you can't connect to it. A Google search turns up lots:

Are you sure your telnet client can use IPv6? There's a program called telnet6 for a reason. Also, if you're going with IPv6, why bother with telnet, which is old, unsafe, and unused (mostly) these days. That's why SSH is usually used.
http://tldp.org/HOWTO/html_single/Linux+IPv6-HOWTO/

You may also need to add "flags = IPv6" in the service entry in /etc/xinetd.d.

ashok.g · 07-26-2010, 01:26 AM

Quote:

Originally Posted by TB0ne

How about telling us what version/distro of Linux you're using??

I'm using RHEL AS 4.

Quote:

Originally Posted by TB0ne

And from your first post, telnet isn't showing up in nmap, so it's no surprise you can't connect to it. A Google search turns up lots:

Are you sure your telnet client can use IPv6?

I'm able to telnet to IPv6 addresses using all ports other than 23.

Quote:

Originally Posted by TB0ne

You may also need to add "flags = IPv6" in the service entry in /etc/xinetd.d.

In which file under /etc/xinetd.d. Is it telnet? I assumed it as telnet and edited the field. But no use.

prasad.k · 11-21-2012, 09:28 AM

My issue got resolved on Linux (release 2.6.18-128.el5) by randomly enabling telnet in one of the three files under /etc/xinetd.d/

telnet
krb5-telnet
ekrb5-telnet

Give a try !

prasad.k · 11-21-2012, 09:31 AM

contd to above post .....

This is how the file should look like

[user@host ~]# cat /etc/xinetd.d/krb5-telnet
# default: off
# description: The kerberized telnet server accepts normal telnet sessions, \
# but can also use Kerberos 5 authentication.
service telnet
{
flags = REUSE IPv6
socket_type = stream
wait = no
user = root
server = /usr/kerberos/sbin/telnetd
log_on_failure += USERID
disable = no
}