aws(1)

- AWS의 svr1과 svr2에 ssh 이용하여 접속하기

PC>  ssh -i 키파일  ubuntu@svr1의IP주소

svr1에 접속 후 

svr1> ssh -i 키파일  ec2-user@svr2의IP주소
 
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- NAT Gateway
  private subnet의 EC2들이 외부(인터넷) 통신이 가능하도록 하는 서비스

  NAT Gateway 생성 :  public subnet에 위치해야하고, 탄력적IP주소를 할당받아서 생성함.

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- private subnet에 있는 EC2에 도커 설치(Amazon Linux 2)

  # sudo amazon-linux-extras install docker
  # sudo service  docker start
  # sudo usermod -a -G docker ec2-user

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- SSH 서비스 : 원격에서 명령을 수행할 수 있는 서비스. 송수신되는 데이터는 암호화됨.
                 TCP 22번.  
                 openssh 패키지를 사용함.(서버프로그램/ 클라이언트 프로그램)
 
- openssh 서버 프로그램 설치 : sudo apt install openssh-server
                                          sudo dnf install openssh-server

- SSH 인증방식 : 패스워드 인증,  공개키 인증
                      1) 패스워드 인증 : ID/PW 인증
                      2) 공개키 인증 : ID/SSH키(개인키) 인증   
                                            공개키 알고리즘(rsa, dsa 중에 rsa 사용함)
                      3) SSH키 생성 :  ssh-keygen -t rsa -b 2048       
                                            키저장 위치와 파일명 지정할 수 있음.
                                            passphrase를 설정할 수 있음.  => SSH키를 보호하기 위한 비밀번호

                      4) SSH키 기본생성위치 :  ~/.ssh    => 사용자의 홈디렉토리에 .ssh 디렉토리 생성됨.
                      5) SSH키를 기본값으로 생성시 
                           id_rsa(개인키)   id_rsa.pub(공개키)
                      6) openssh 서버는 공개키를 authorized_keys에 보관함.
                      7) SSH는 SSH키를 이용해서 세션키(대칭키,비밀키)를 교환하고, 교환된 세션키를
                          이용해서 사용자데이터를 암복호화 함.

- SSH 접속 :  1) 패스워드 인증  
                     ssh 사용자ID@서버IP주소
                     password:
                                     
                  2) 공개키 인증
                     ssh -i 개인키  사용자ID@서버IP주소 

- scp 이용한 파일 복사
                 1) 클라이언트에서 서버로 복사하기
                    scp -i 개인키   복사할파일명  사용자ID@서버IP주소:복사할위치
                    scp -i kyt_keypair.pem  testfile  ubuntu@서버IP주소:/home/ubuntu

                 2) 서버에서 클라이언트로 복사하기
                    scp -i 개인키  사용자ID@서버IP주소:복사할파일위치/파일명    복사될위치
                   scp -i kyt_keypair.pem  ubuntu@서버IP주소:/home/ubuntu/testfile   .

- 공개키를 원하는 서버에 복사하기
  ssh-copy-id 공개키  사용자ID@서버IP주소
  

- ssh 패스워드 인증 가능하도록 설정 변경

sudo vi /etc/ssh/sshd_config
PasswordAuthenticatio yes   로 변경하고 저장

sudo passwd 사용자ID   => 사용자의 패스워드 설정 

sudo systemctl restart sshd    => ssh 서비스 재시작