# error message ping: socket: Operation not permitted sysctl -w net.ipv4.ping_group_range="0 1000"

환경 OS : Ubuntu 20.04 LTS error 'Waiting for cache lock: Could not get lock /var/lib/dpkg/lock-frontend’ solution sudo rm /var/lib/apt/lists/lock sudo rm /var/cache/apt/archives/lock sudo rm /var/lib/dpkg/lock* # 이후 패키지 업데이트 sudo dpkg --configure -a sudo apt update

환경 OS : Ubuntu 20.04 LTS apt install libpam-google-authenticator # 2차 인증 적용할 계정으로 전환 su - ${id} google-authenticator vi /etc/pam.d/sshd # 추가 # google otp auth required pam_google_authenticator.so nullok vi /etc/ssh/sshd_config # 변경 UsePAM yes ChallengeResponseAuthentication Yes systemctl restart sshd # key 조회 가능 cat /home/${user}/.google_authenticator

목적 : sftp 프로토콜 사용시 사용자의 접속 시간, ip, 경로를 확인하기 위함 환경 : Ubuntu 20.04 man sftp-server -f type = DAEMON, USER, AUTH, LOCAL0, LOCAL1, LOCAL2, LOCAL3, LOCAL4, LOCAL5, LOCAL6, LOCAL7. -l type = QUIET, FATAL, ERROR, INFO, VERBOSE, DEBUG, DEBUG1, DEBUG2, DEBUG3 vi /etc/ssh/sshd_config # Logging SyslogFacility local4 #LogLevel DEBUG1 # override default of no subsystems # log_facility, log_level 설정 # add Sub..

vi /etc/nova/nova.conf root@test:/etc/nova# cat nova.conf | egrep allocation # The image preallocation mode to use. For more information, refer to the # Virtual CPU to physical CPU allocation ratio. For more information, refer to #cpu_allocation_ratio = # Virtual RAM to physical RAM allocation ratio. For more information, refer to #ram_allocation_ratio = # Virtual disk to physical disk allocatio..

환경 : Ubuntu 20.04 # ntp install apt-get install ntp # vi /etc/ntp.conf # /etc/ntp.conf, configuration for ntpd; see ntp.conf(5) for help driftfile /var/lib/ntp/ntp.drift # Leap seconds definition provided by tzdata leapfile /usr/share/zoneinfo/leap-seconds.list # Enable this if you want statistics to be logged. #statsdir /var/log/ntpstats/ statistics loopstats peerstats clockstats filegen loopst..

error 1. postdrop: warning: unable to look up public/pickup: No such file or directory mkfifo /var/spool/postfix/public/pickup systemctl restart postfix 2. postmap: fatal: bad string length 0

# postfix 재시작 postfix reload # hash 파일 등록 postmap /etc/postfix/${filename} # postfix 설정 확인 postconf -n # 메일 큐 전체 비우기 postfix flush or postfix -f # 메일 큐 확인 mailq # 메일큐 전체 삭제 postsuper -d ALL # 메일큐 중 deferred 상태만 삭제 postsuper -d ALL deferred

환경 : Ubuntu 20.04 패키지 : postfix, sasl # postfix install apt-get install postfix /etc/postfix/main.cf # See /usr/share/postfix/main.cf.dist for a commented, more complete version # Debian specific: Specifying a file name will cause the first # line of that file to be used as the name. The Debian default # is /etc/mailname. #myorigin = /etc/mailname smtpd_banner = $myhostname ESMTP $mail_name (Ubu..

문제 E: could not get lock /var/lib/dpkg/lock-frontend. It is held by process (unattended-upgr) N: Be aware that removing the lock file is not a solution and may break your system. E: Unable to acquire the dpkg frontend lock (/var/lib/dpgk/lock-frontend), is a nother process using it? 해결방법 killall apt apt-get rm /var/lib/apt/lists/lock rm /var/cache/apt/archives/lock rm /var/lib/dpkg/lock* dpkg --..

# error unable to resolve host ${hostname}: Name or service not known solution vi /etc/hosts 127.0.0.1 ${hostname} #hostname add

root@test1:~# passwd root New password: Retype new password: Sorry, passwords do not match. passwd: Authentication token manipulation error passwd: password unchanged root@test:~# passwd root New password: Retype new password: Sorry, passwords do not match. passwd: Module is unknown passwd: password unchanged solution chmod 0640 /etc/shadow mount -o remount,rw /