리눅스 텔넷 서버

telnet 클라이언트에 대해서는 telnet 문서를 참고하십시오.

linux telnet server
telnet 서버, telnet 서비스, telnet 데몬

1 설치 확인

CentOS 6.0 최소 설치시에는 없었다. telnet과 telnet-server 패키지가 필요하고, telnet-server 패키지에는 xinetd 패키지가 필요하다.

[root@jmnote ~]# rpm -qa | grep telnet

→ telnet과 telnet-server가 설치되지 않았다. ("설치 재확인" 문단과 비교해보라.)

2 설치

xinetd가 설치되지 않았다면 함께 설치된다.

[root@jmnote ~]# yum install telnet-server -y
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
Setting up Install Process
Resolving Dependencies
--> Running transaction check
---> Package telnet-server.x86_64 1:0.17-47.el6 set to be updated
--> Processing Dependency: xinetd for package: 1:telnet-server-0.17-47.el6.x86_64
--> Running transaction check
---> Package xinetd.x86_64 2:2.3.14-34.el6 set to be updated
--> Finished Dependency Resolution

Dependencies Resolved

===================================================================================================================================
 Package                           Arch                       Version                               Repository                Size
===================================================================================================================================
Installing:
 telnet-server                     x86_64                     1:0.17-47.el6                         Daum                      36 k
Installing for dependencies:
 xinetd                            x86_64                     2:2.3.14-34.el6                       Daum                     121 k

Transaction Summary
===================================================================================================================================
Install       2 Package(s)
Upgrade       0 Package(s)

Total download size: 157 k
Installed size: 312 k
... (생략)
Installed:
  telnet-server.x86_64 1:0.17-47.el6                                                                                               

Dependency Installed:
  xinetd.x86_64 2:2.3.14-34.el6                                                                                                    

Complete!

[root@jmnote ~]# yum install telnet -y
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
Setting up Install Process
Resolving Dependencies
--> Running transaction check
---> Package telnet.x86_64 1:0.17-47.el6 set to be updated
--> Finished Dependency Resolution

Dependencies Resolved

===================================================================================================================================
 Package                      Arch                         Version                                Repository                  Size
===================================================================================================================================
Installing:
 telnet                       x86_64                       1:0.17-47.el6                          Daum                        58 k

Transaction Summary
===================================================================================================================================
Install       1 Package(s)
Upgrade       0 Package(s)

Total download size: 58 k
Installed size: 109 k
... (생략)
Installed:
  telnet.x86_64 1:0.17-47.el6                                                                                                      

Complete!

3 설치 재확인

[root@jmnote ~]# rpm -qa | grep telnet
telnet-server-0.17-47.el6.x86_64
telnet-0.17-47.el6.x86_64

4 설정 파일 수정

/etc/xinetd.d/telnet 문서를 참고하십시오.

[root@jmnote ~]# cat /etc/xinetd.d/telnet
# 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		= yes
}

[root@jmnote ~]# vi /etc/xinetd.d/telnet

disable = yes을 disable = no로 바꾸어 저장한다.

5 xinetd 재시작

[root@jmnote ~]# service xinetd restart
Stopping xinetd:                                           [FAILED]
Starting xinetd:                                           [  OK  ]

Stopping에서 FAILED는 신경쓰지 말자.^[1]

6 포트/프로세스 확인

[root@jmnote ~]# netstat -anp | grep ":23"
tcp        0      0 0.0.0.0:23                  0.0.0.0:*                   LISTEN      15330/xinetd

→ xinetd가 텔넷 기본포트인 23을 LISTEN 중이다.

[root@jmnote ~]# netstat -anp | grep ":23"
tcp        0      0 :::23                       :::*                        LISTEN      4601/xinetd

→ "0.0.0.0:23" 대신 ":::23"라고 표시되는 경우도 있는데 의미는 같다.

7 한방 명령어

위 과정을 한번에 실행하는 명령어 모음. 이 명령어 모음을 사용함으로써 발생하는 오류/손해에 대해 책임을 지지 않습니다!

설치 → 설정 → 확인

yum install -y telnet
yum install -y telnet-server
cp /etc/xinetd.d/telnet /etc/xinetd.d/telnet.OLD
sed -i 's/disable\t\t= yes/disable\t\t= no/' /etc/xinetd.d/telnet
diff /etc/xinetd.d/telnet.OLD /etc/xinetd.d/telnet
service xinetd restart
sleep 1
netstat -anp | grep ":23"

8 같이 보기

9 주석

↑ 처음 설치하면 stopped이므로 당연히 stop 불가...

[1] 처음 설치하면 stopped이므로 당연히 stop 불가...

[1]