I. Inspection1, [[email protected] ~]# telnet
Bash:telnet:command not found
2, query whether to install the Telnet package, the results are as follows:
[[email protected] ~]# Rpm-qa telnet*
telnet-server-0.17-47.el6.i686
3, also inquires the state of xinetd:
[[email protected] ~]# Service xinetd Status
XINETD (PID 2967) is running ...
4. Use the NTSYSV command to turn on the Telnet service, and also view the/etc/xinetd.d/telnet file, change "Disable = yes" to "Disable = no", and restart the service [[email protected] /] #service xinetd restart
In the system service, also checked, Telnet service and xinetd are also working status.
two. Installation Services
Workaround, re-install the Telnet client.
CentOS, Ubuntu
Yum list telnet* viewing Telnet-related installation packages
Yum Install telnet-server telnet Service
Yum Install telnet.* telnet Client
Note that installing #yum install xinetd (Note under root) is needed before installation because Telnet relies on the xinetd service to start, so install the service first
three. Configure Telnet
Method One: Use Ntsysv, in the window that appears, the Telnet is selected, and then press OK!
Method Two: Use the Chkconfig command to open directly
#chkconfig Telnet on
Method Three: Directly modify the configuration file
Vi/etc/xinetd.d/telnet
This is usually the case:
# Default:yes
# description:the Telnet Server servestelnet 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 = yes
}
Just change "disable= yes" to "Disable=no"
iv. activation of services
Telnet is hung under the xinetd, so naturally just reactivate xinetd will be able to re-read the xinetd inside the settings, so just set the telnet nature
can be activated as well.
# servicexinetd Restart
or #/etc/rc.d/init.d/xinetd restart.
Five. Iptables firewall will block Telnet, so it needs to be allowed in iptables, with the following command
When you start the Telnet service, you can use the NETSTAT–TUNLP command to see the port used by the Telnet service, and you can find 23. Use the following command to turn on these ports:
iptables-i input-p TCP--dport 23-jaccept
iptables-i input-p UDP--dport 23-jaccept
Service Iptables Save//Save
Service iptables Restart//restart firewall
or a little ruthless!! Shut down the firewall!
Service iptables Stop
vi. Possible issues:
Let's look at two types of errors:
The first type:
[[email protected] ~]# telnet 192.168.1.87
Trying 192.168.1.87 ...
Telnet:connect to address 192.168.1.87:noroute to host
Telnet:unable to connect-to-remote host:no route to host
Workaround: The firewall does not allow the Telnet service, the connection is blocked, the default CentOS only allows SSH, so go to its custom options, before Telnet tick!
The second type:
[[email protected] xinetd.d]# telnet 172.25.1.3
Trying 172.25.1.3 ...
Connected to 172.25.1.3 (172.25.1.3).
Escape character is ' ^] '.
Getnameinfo:localhost:Success
Temporary failure in name Resolution:illegal seek
Connection closed by foreign host.
This one is the/etc/hosts file configuration problem
Workaround: I add two IP address in it, the content is as follows:
[[email protected] ~]$ more/etc/hosts
# don't remove the following line, orvarious programs
# that require network functionality Willfail.
127.0.0.1localhost.localdomainlocalhost
:: 1localhost6.localdomain6localhost6
192.168.1.88
192.168.1.86
Description: Because the client's name is not written in the letter, the content format should be 127.0.0.1 Pcname
Telnet cannot be used!!! Tip:-bash:telnet:command not found
