vi /etc/mail/local-host-names
# local-host-names - include all aliases for your machine here.
my.centos7.com
3. sendmail 서비스 시작
service sendmail start
#sendmail 이 리눅스 부팅시 실행되도록 설정.
chkconfig --level 2345 sendmail on
4. RELAY (IP 허용) :/etc/mail/access
접속 허용 IP 대역 추가 (Connect:192.168 RELAY)
access ip 적용 : makemap hash access < access
vi /etc/mail/access
# By default we allow relaying from localhost...
Connect:localhost.localdomain RELAY
Connect:localhost RELAY
Connect:127.0.0.1 RELAY
Connect:192.168 RELAY
cd /etc/mail
makemap hash access < access
5. sendmail 테스트
5-4 번이 헷갈릴수도 있습니다.
꼭 DATA 입력후 엔터를 누른신 후 본문을 작성해 주세요 .
본문 작성이 끝나면 마침표로 "." 작성 완료를 해주세요
5-1.telnet 접속 telnet centos7 25
5-2.발신 메일 주소 입력 MAIL FROM:example@test.com
5-3.수신 메일 주소 입력 RCPT TO:test_user@tmax.co.kr
5-4. "DATA" 입력 후 본문 입력 "." 마침표로 메세지 발송 DATA
SUBJECT:Test Mail
5-5. 접속 종료
quit
telnet centos7 25 Trying 192.168.17.56... Connected to centos7. Escape character is '^]'. 220 my.centos7.com ESMTP Sendmail 8.14.7/8.14.7; Mon, 4 Apr 2022 18:09:28 +0900 MAIL FROM:example@test.com 250 2.1.0 example@test.com... Sender ok RCPT TO:usermail@daum.net 250 2.1.5 usermail@daum.net... Recipient ok DATA 354 Enter mail, end with "." on a line by itself SUBJECT:Test Mail . 250 2.0.0 23499Sdm021395 Message accepted for delivery quit 221 2.0.0 my.centos7.com closing connection Connection closed by foreign host.
$ telnet 192.168.17.56 Trying 192.168.17.56... Connected to 192.168.17.56. Escape character is '^]'.
Kernel 3.10.0-1160.el7.x86_64 on an x86_64 centos7 login: docker_test Password: Last login: Thu Mar 31 15:54:04 on pts/9
3.Telnet Command
아래 명령은 telnet 사용 기본 명령어 입니다.
#telnet 서비스 시작
systemctl start telnet.socket
#시스템 시작 시 자동으로 telnet 서버가 시작될 수 있게 활성화 시킨다.
systemctl enable telnet.socket
#telnet 서비스 정지
systemctl stop telnet.socket
systemctl disable telnet.socket
#tlent 서비스 상태 확인
systemctl status telnet.socket
ubuntu@ubuntu:~$ pwd /home/ubuntu ubuntu@ubuntu:~$ whoami ubuntu ubuntu@ubuntu:~$ sudo passwd root [sudo] password for ubuntu: New password: Retype new password: passwd: password updated successfully ubuntu@ubuntu:~$ su - root Password: root@ubuntu:~# whoami root root@ubuntu:~#
SSH Root 접속 허용 설정 (/etc/ssh/sshd_config)
#PermitRootLogin prohibit-password => PermitRootLogin yes 설정
root@ubuntu:~# vi /etc/ssh/sshd_config
# $OpenBSD: sshd_config,v 1.103 2018/04/09 20:41:22 tj Exp $
# This is the sshd server system-wide configuration file. See
# sshd_config(5) for more information.
# This sshd was compiled with PATH=/usr/bin:/bin:/usr/sbin:/sbin
# The strategy used for options in the default sshd_config shipped with
# OpenSSH is to specify options with their default value where
# possible, but leave them commented. Uncommented options override the
# default value.
Include /etc/ssh/sshd_config.d/*.conf
#Port 22
#AddressFamily any
#ListenAddress 0.0.0.0
#ListenAddress ::
#HostKey /etc/ssh/ssh_host_rsa_key
#HostKey /etc/ssh/ssh_host_ecdsa_key
#HostKey /etc/ssh/ssh_host_ed25519_key
# Ciphers and keying
#RekeyLimit default none
# Logging
#SyslogFacility AUTH
#LogLevel INFO
# Authentication:
#LoginGraceTime 2m
#PermitRootLogin prohibit-password
PermitRootLogin yes
#StrictModes yes
#MaxAuthTries 6
#MaxSessions 10
SSH 서비스 재 시작 후 접속
sudo service ssh restart
일반계정 ssh ROOT 접속
일반계정에서 접속이 가능 한지 확인해보겠습니다.
ubuntu 계정에서 root 로 정상적으로 접속이 되고 있습니다.
ubuntu@ubuntu:~$ ssh root@192.168.58.130 The authenticity of host '192.168.58.130 (192.168.58.130)' can't be established. ECDSA key fingerprint is SHA256:HXSV8v929Lw15GM4sjnyr8Od6Y/84S1jrajWaC7PFtk. Are you sure you want to continue connecting (yes/no/[fingerprint])? yes Warning: Permanently added '192.168.58.130' (ECDSA) to the list of known hosts. root@192.168.58.130's password: tiberoPermission denied, please try again. root@192.168.58.130's password: Welcome to Ubuntu 20.04.4 LTS (GNU/Linux 5.13.0-37-generic x86_64)
17 updates can be applied immediately. To see these additional updates run: apt list --upgradable
Your Hardware Enablement Stack (HWE) is supported until April 2025. *** System restart required *** Last login: Sat Mar 26 07:13:22 2022 from 192.168.58.130 root@ubuntu:~# whoami root
GUI 리스트에서 root 접속 활성화 하기
아래 3개의 파일을 수정 하면 gui 리스트에 root 계정 접속도 가능합니다.
주석 처리 (#) 를 해주세요.
1./etc/gdm3/custom.conf 수정
2./etc/pam.d/gdm-password
3./etc/pam.d/gdm-autologin
vi /etc/gdm3/custom.conf
# Enabling automatic login
AutomaticLoginEnable = true
AutomaticLogin = root
[security]
AllowRoot=true
vi /etc/pam.d/gdm-password
#auth required pam_succeed_if.so user != root quiet_success
vi /etc/pam.d/gdm-autologin
#auth required pam_succeed_if.so user != root quiet_success
