Ping works while telnet fails

pingtelnet

I have a Windows 2008R2 Server named SERV1 connected to a Unix machine UNI1.

I can ping but I can't telnet.

I have installed the telnet client on server R2. I disabled the Windows Firewall on R2. Do I need to check any services running in services.msc on R2 machine?

Best Answer

To telnet from a Windows computer to a Unix computer you need to ensure that

  • Windows has telnet client installed (it is not installed in latest Windows)
  • Windows firewall is not blocking outgoing Telnet (very unlikely)
  • Windows can resolve server's name (e.g. through DNS or local hosts file)
  • Unix server has Telnet service enabled (increasingly being disable to encourage SSH use)
  • No intermdiate firewalls are blocking Telnet (unlikely if both computers are in same subnet)
  • You have valid Unix login credentials (user name and password)

Since you didn't post an actual error message but just said you "can't do telnet" - we can only guess at the problem.

To check if the Telnet service is runnning, log on at the Unix server console and use this command:

netstat -a | grep "telnet.*LISTEN"

The output should be this

tcp        0      0  *.telnet               *.*                    LISTEN

Note: If you have problems, update your question with the actual command and error messages by using cut & paste (then edit only if needed to change confidential details)

Update:

Redhat / Fedora

Use these commands

chkconfig telnet on
chkconfig --list | grep telnet

The output from the second command should be

   telnet: on

Ubuntu

sudo apt-get install telnetd
sudo /etc/init.d/inetd restart

Once installed, from the GUI, select Administration, Services and enable Telnet

Distros using Xinetd

You need a file named /etc/xinetd.d/telnet with contents something like this

# default: on
# description: The telnet server serves telnet sessions; it uses \
#       unencrypted username/password pairs for authentication.
service telnet
{
        flags           = REUSE
        socket_type     = stream
        wait            = no
        user            = root
        server          = /usr/sbin/in.telnetd
        log_on_failure  += USERID
        disable         = no
}

Warning!

You shouldn't be doing this unless you are familiar with Linux, with Linux commands, with editors such as vi and have good backups and are prepared to reinstall if it all goes horribly wrong. If other people rely on this server, you should employ a systems administrator who is familiar with the particular Linux distribution you are using.

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