Linux_Learning_Notes-1

###vncviewer### a. vncviewer -shared -viewonly 192.168.0.254:1 a1. '-shared' - means share session with others a2. '-viewonly' - can not control only view b. vncviewer -shared -viewonly 192.168.0.254:1 -passwd /etc/vncpasswd b1. use 'vncserver create a passwd file in ~/.vnc/passwd, copy to /etc/vncpasswd ###/etc/yum.repos/*### [Server] name=LocalServer baseurl=file:///mnt/server gpgcheck=0 [Cluster] name=Cluster baseurl=ftp://192.168.0.254/pub/5.4/cluster gpgcheck=0 enable=0 ###Package Management with RPM### Features: 1. Compression of packages 2. SHA-256 hashes are used to sign packages 3. RPM DB: '/var/lib/rpm' - tracks installed packages, attributes of package file, etc. 4. 5-Modes of operations: a. Install b. Uninstall c. Upgrade d. Query e. Verify 5. Caveat: Does NOT auto-resolve dependencies: Use 'yum' 6. Caveat: RPM does NOT track non-RPM programs/apps: i.e. '*.tar.gz' || '*.tar.bz2' Tasks: 1. Query a. 'rpm -qa' - dumps ALL installed packages (RPMs) b. 'rpm -qa | grep grep' - 'grep-2.6.3-2.el6.x86_64' 'grep' - main name of package '2.6.3-2' - package version 'el6.x86_64' - RedHat Version & Platform c. 'rpm -qi grep' - returns metadata about 'grep' package d. 'rpm -ql grep' - enumerates the contents of the package: 'grep' e. 'rpm -qf /bin/grep' - enumerates the file's package membership f. 'rpm -qd grep' - enumerates the included documentation g. 'rpm -qc lftp' - enumerates a package's configuration file(s) h. 'rpm -qpi unix2dos-2.2-35.el6.x86_64.rpm 3. Verify - Verifies file system contents against installed package in RPM DB Note: Returns: '.' per test performed if the test passed Note: If test fails, one of the following will be returned: 5(MD5), S(file size), L(symlink), T(mod time), D(device), m(mode), ?(unreadable file), U(user), G(group) a. 'rpm -Vvf /bin/grep' - compares: /bin/grep to 'grep' RPM b. 'mv /bin/grep /bin/grep.original && touch /bin/grep' SM5....T. /bin/grep 3. Install - Works if package does NOT exist on the system a. 'rpm -ivh unix2dos-2.2-35.el6.x86_64.rpm 4. Upgrade - Install and/or Upgrades a. 'rpm -Uvh unix2dos-2.2-35.el6.x86_64.rpm' b. 'rpm -Uvh --replacepkgs unix2dos-2.2-35.el6.x86_64.rpm 5. Uninstall a. 'rpm -e grep' - checks dependencies and warns where appropriate 6. Import RedHat RPM GPG Key to confirm package signatures: a. 'rpm --import /etc/pki/rpm-gpg/RPM-GPG-KEY-redhat-release' b. 'rpm -qa gpg-pubkey*' ###find### 1. find / -mtime +3 - three days ago 2. find / -mtime -3 - within three days 3. find / -newer a.txt ypcat -d <NIS> -h <DNS> passwd ypcat -d <NIS> -h <DNS> shadow yum whatprovides filename su [-] user - the '-' option makes the new shell a login shell e2label /dev/sda1 blkid /dev/sda1 - show UUID and TYPE dumpe2fs /dev/sda1 dd < /dev/sda > mbr bs=512 count=1 default options: rw, suid, dev, exec, acl, async, fuser cryptsetup crypt partition Linux LVM (0x8e) lvreduce -L -100M /dev/vgsrv/home mount -o remount,rw / nice -20 - 19 man -k passwd 1 User Commands 2. System Calls 3. C Library Functions 4. Devices and Special Files 5. File Formats and Conventions 6. Game et. Al. 7. Miscellanea 8. System Administration tools and Deamons man 5 shadow 1. login name 2. encrypted password 3. date of last password change 4. minimum password age 5. maximum password age 6. password warning period 7. password inactivity period 8. account expiration date 9. reserved field 'ln -s' MUST use absolute path 'cp -p' keep the owner and mtime 'mkdir -p a/b/c/d '\rm' do not run alias 'rmdir -p' 'updatedb' 'rsync src dest' 'rsync -r src dest' - sync dir 'rsync -r /etc/ .' - /etc/ == /etc/* - not include '/etc' 'rsync -a src dest' - '-a' == '-rlptgoD' 'rsync -z src dest' - compress 'yum provides */scp' SSH Auto Login 1. ssh-keygen a. id_rsa - key b. id_rsa.pub - lock 2. ssh-copy-id -i ~/.ssh/id_rsa.pub user@192.168.0.101 3. ssh-agent bash 4. ssh-add vncserver -kill :2 vncpasswd setfacl getfacl PasswordAuthEntication yes file-roller tar zcf etc.tar.gz /etc tar jcf etc.tar.bz2 /etc http://localhost/manual /etc/motd /etc/ssh/sshd_conf AllowUsers student PasswordAuthentication no PermitRootLogin no wireshark ip.addr==192.168.0.23 /etc/sysconfig/vncservers vncviewer -via whx@localhost localhost:2 tune2fs -l /dev/sda1 tune2fs -L boot /dev/sd1 tune2fs -o acl /dev/sda3 swapon -s dd if=/dev/zero of=/tmp/swapfile bs=1024k count=100 mkswap /tmp/swapfile swapon /tmp/swapfile update /etc/fstab file /tmp/swapfile swap swap defaults 0 0 AMD - svm Intel - vmx lm - support 64-bit /etc/resolv.conf nameserver 192.168.0.254 echo westos | passwd --stdin root Disable -> Enforcing - need reboot Disable -> Permissive - need reboot Enforcing <-> Permissive - don't need reboot grub> root (hd0,0) grub> kernel /vmlinuz-[TAB] ro root=/dev/mapper/vfsrv-root grub> initrd /initramfs[TAB] grub> boot restorecon -R dir Kernel-Parameters yum -y install kernel-doc console=ttyS0 enforcing=0|1 (0 - Permissive, 1 - Enforcing) selinux=1|1 (0 - disable, 1 - enable) init=/bin/bash pvcreate /dev/sda5 vgextent vol0 /dev/sda5 lvextent -L 30G /dev/vol0/root resize2fs /dev/vol0/root GRUP - press A setenforce 0|1 getenforce vsftp - /var/ftp Google [ index /pub ] Google [ nagios site:www.ibm.com ] if boot is a sym link 'rm -rf boot/' can not delete it