When assigned to the ref attribute for ou=people,dc=example,dc=com, which of the following Show A. Which
of the following parameters should be set in main.cf to enable TLS in Postfix? Which of the following rule directives will email
and when the Mail Configuration rule is violated? The correct crontab entry to execute the script chklog once per hour between 3 p.m. and 5 p.m. on Monday and Thursday each week is, which of the following? A. 0 3,4,5 2,5 chklog Ch. 10 Common Administrative Tasks Ch. 11 Compression, System Backup, and Software Installation Ch. 12 Network Configuration Ch. 13 Configuring Network Services and Cloud Technologies Ch. 14 Security, Troubleshooting, and Performance Upgrade to remove ads Only ₩37,125/year
Terms in this set (442)What is the purpose of the ldd command? ldd prints the shared objects (shared libraries) required by each program or shared object specified on the command line. What is located in the /var directory? Log files List 3 'journaling' file systems? Which one is not a journaling file system? EXT3, XFS, EXT4 EXT2 List two "pseudo" filesystems. What do they contain? /proc which contains processes running on the system and /sys which contains system info about kernel modules and hardware What is an inode? An inode contains information about the file or folder, such as ownership and permissions. The temporary file system that is loaded at boot is called? initrd or initial ramdisk / initial file system What is contained in the /etc/fstab file? It contains the list of mount points and their locations and is used as a reference for automounting file systems. What is the purpose of the /etc/hosts file? This is the local DNS look up location, and by default it is checked first for DNS names. What do you need to make sure is done before running the "fsck" utility on a drive? The drive needs to be unmounted first. In the nmcli tool, what is meant by dev and what is meant by con? dev is short for device and refers to the hardware that is on the computer. con refers to a network connection. What is the output of the following command? This command as written will output the current date and time settings for the system. What is the name of the boot process that allows a client to mount a network share as its root file system? Boot from NFS. In the Pre-Execution Environment, or PXE boot, the client machine searches for a server machine from which to download the boot image over the trivial file transfer protocol. What is network bonding? This is the process of creating a single interface from multiple network interfaces. In system logging via rsyslog, what is the purpose of a third-party agent? It converts the native logging format to one that can be read on the rsyslog server. What is the name of the system used to resolve IP addresses to hostnames? DNS In networked systems, what is the name of the protocol used to dynamically assign IP addresses to network interfaces? DHCP What is the purpose of rotating the log files? This prevents the logs from becoming too large to parse or archive, and it assists with searching the logs for entries if each log file encompasses a smaller time frame. The encrypted passwords for users on the system are located in what file? /etc/shadow Which of the following commands will search for the file exmaple.sh in the current directory, recursively? find . -name example.sh The -name searches recursively Which command is used to view the logs collected by systemd? journalctl When issuing the userdel command, what is the function of the -r flag? This will remove the user's home directory in addition to removing the users account. What is accomplished by the command: usermod -a -G wheel example This will append the wheel group to the list of groups that example is a member of. The command will append (-a) the indicated group (-G wheel) to the groups that the user, in this case example, is a member of. In the /etc/sudoers file, what is the difference between wheel and %wheel? wheel is a user and %wheel is a group. What is located in the directory /etc/cups/? This is the location of the configuration files for the printing subsystem that are set using the interface located at http://localhost:631 What is displayed when we run the ls -Z command? It shows the SELinux related information about the files in the current directory. Which command should be used to edit the sudoers file? sudo visudo In the following octal notation, what are the effective permissions on this file: 0644 This represents read/write for the owner, read for the group, and read for other with no setuid, setgid or sticky bit set. Which of the following are part of a Firewall ACL (Access Control List)? Choose three. Source, Protocol, Destination Which command will generate SSH keys for use when connecting to a computer via SSH? ssh_keygen What is the difference between a privileged and a non-privileged port? Running services on privileged ports requires root privileges. What is the difference between a standard user and a service user? Standard users have login shells, while service users are only to be used for services. They do not have login shells. When connecting to a computer via a secure shell, where is the fingerprint stored so that it can be referenced to ensure that the remote machine is not an impersonator? ~/.ssh/known_hosts
A junior administrator has installed an Apache web server on one of your RHEL instances. The administrator cannot get the Apache instance to log errors. You check into the issue and run ausearch with the following result: type=AVC msg=audit(1455805464.059:137): avc: denied { append } for pid=3128 comm="httpd" name="error_log" dev="sdb1" ino=31221 scontext=system_u:system_r:httpd_t:s0 tcontext=system_u:object_r:var_run_t:s0 tclass=file permissive=0 What is the most likely cause? There is a type mismatch on the source and target contexts. The target context is most likely the issue, since it is not in the httpd_ t context. Which of the following are firewall configuration tools? Choose three. UFW, iptables, firewalld What is the purpose of a pseudoterminal? The pseudoterminal is terminal emulation that is provided to programs. When a service starts and it binds to a port, where is this port binding information located? /etc/services Which of the following are archive and restore utilities? Select three. dd, cpio, tar What is the purpose of the ssh-copy-id command? It is used to copy a user's keys over to a remote server, thus "keying" the server. When installing a new CUPS print server, you are attempting to access the management console from the server itself, what is the correct URI? Localhost:631 or 127.0.0.1:631 On a system with four CPUs, what percentage of total CPU is being used with a load average of 1.00? The load average is divided among the CPUs. In this case only one of the CPUs is being loaded to 100% and so the actual CPU usage is 25%. By default, on a system that uses a BIOS, how do you access the GRUB boot options menu? Once the system post has completed, and before the OS loads, hold down the shift key. What is the purpose of single user mode? It allows passwordless access as the root user so that emergency maintenance can be performed on the system. A user is having an issue logging in and you are wanting to troubleshoot. Which log file would you inspect to see the authentication error message? /var/log/secure What is the purpose of the partprobe command? Once a new partition is created, the partprobe command is used to update the kernel with the new partition information. What is meant by a chroot jail? This is a technique which changes the effective root of the file system for a process or user so that the user or process can not traverse the directory tree above the new effective root. What command would be used to determine if a file is immutable? lsattr What is a whois lookup? This is a search for the IANA registration for a domain, it provides contact information for the domain administrator What command would be used to configure the network interfaces via from the command line. nmcli What is the purpose of the command lsof? It lists all of the open files on a system. What information is displayed by issuing the free command? The memory usage on the system, both free memory and memory in use What is the purpose of a load balancer? It is placed in front of servers to allow them to be used together, and provides fault tolerance in the event one of the servers goes offline. What is an ARP packet? This is a packet that is used to resolve local network addresses. Which of the following is a benefit of infrastructure as code? Select 2 The state of the infrastructure can be checked in to SCM for versioning and tracking. When load exceeds resources, more resources can be deployed from the code base that are the same as the existing resources. What is the purpose of the $PATH variable? It is a list of locations that are searched for executable files. Once a set of procedures has been identified, what is the term for executing the procedures in a logical order? automation is the logical ordering of procedures. Orchestration is the management of automated tasks. Which of the following are reasons to use configuration management? Select 3 Monitoring, Patch management, Inventory Management What is a unit file? A unit is an object that systemd can control, and a unit file describes how it interacts with that unit. What is meant by "sourcing" a script? This is using the source directive to include an external script file in the current script so that its variables and functions can be referenced. What two files are needed to create a systemd service job? .timer and .service file, each of which must have the same name. What are the 3 sections that need to be present inside of a .timer file? Unit, Timer, Install What needs to be inside of the [Timer] section of a .timer file? OnCalendar (has the time in format *-- 23:00:00 for example), Persistent (boolean), and Unit (the associated .service file) If you have a shell script that is associated with a systemd job, where should it be placed? /usr/local/sbin Where do systemd .timer and .service files go? /etc/systemd/system What three steps do you have to take after creating a systemd job and placing the files in /etc/systemd/system ? - Reload the daemon with "systemctl daemon-reload" What command would you use to find the files that are owned by some user? sudo find / -user USER What command would you run to change the ownership of files in the directory /opt/myapp to some user? sudo chown -R cloud_user:cloud_user /opt/myapp Which directory contains encrypted paswords for accounts listed in /etc/passwd? /etc/shadow Which directory contains items that will automatically be added to a user's home directory when their account is created? /etc/skel Which configuration file is references by useradd command? What sort of things does this file contain? /etc/default/useradd GROUPID, HOME (users home dir), INACTIVE (value of -1 indicates user's account not disabled if expired), EXPIRE What command would we use if we wanted to see which group has an id of 100? getent group 100 How can we lock some user's account with the name of bcalhoun? What flag is used to unlock the account? usermod -L bcalhoun The -U switch is used to unlock the account Which command and flag would be used to create a service (non-user) account called projectx? useradd -r projectx Which shell is given to a service account? What command would be used to modify the shell for service account called projectx? /sbin/nologin usermod -s /sbin/nologin projectx Which command lists and modifies the aging parameters of a user's password? chage Using the chage command, which flag is used for setting the expiration? chage -E 2019-01-01 bcalhoun How would be change the "engineering" group ID from 1004 to 1100 ? groupmod -g 1100 engineering Which file is used to display a message on the console when someone attempts to login with an account that is using /sbin/nologin? /etc/nologin What is ksh? Shell based on bourne shell, with some features of the C shell added. What is zsh? Shell which includes elements of the bash and Korn shells. Which command displays current environment variables? env Which command displays shell settings or or shell variables for the session? set Describe the two main types of shell environments we need to be aware of. Interactive login shell - created when you log into a console or when you login remotely via SSH. Interactive non-login shell - created when a terminal application such as GNOME terminal is started. How can you tell if you're in a login shell or non-login shell? Command: echo $0, if it returns -bash you're in a login shell Which file sets up system wide environment variables, umask values, bash history controls and is the first file read on a login session? /etc/profile Which directory contains extra script config files for bash which are read in by /etc/profile? /etc/profile.d Which file does .bash_profile call? .bashrc, which then makes a call to /etc/bashrc What are the differences between MBR (Master Boot Record) and GPT (GUID Partition Tables) MBR supported 26 total partitions and was limited to 2TB. GPT ssupports 128 partitions, and supports up to a zettabyte. GPT also contains EUFI which prevents unauthorized operating systems from booting up the system. Which command do we use to view the contents of an initramfs file? lsinitrd What does the dracut command do? Will ceate a new initramfs for kernals on the system and can be used to add and remove modules and drivers from initramfs builds Which flag is added to dracut to specify modules we don't want to add to the initial RAM disk? -o, for example dracut -o "fcoe-uefi" -M -f where: - f creates new initial ram disk with the same name as the one we have installed If we wanted to create a configuration file for dracut to omit modules for us automatically, where would it go? /etc/dracut.conf.d What does the "uname" command do? displays info about the currently running kernal. -m option is machine type and -a prints out all info about kernal What does the "lsmod" command do? displays listing of all currently loaded kernal modules What does the "modprobe" command do? command used to dynamically load and unload kernal modules at runtime. -r removes a module, no argument when adding a module Which file contains the number of seconds a system will wait before rebooting to recover from a kernel panic? /proc/sys/kernel/panic What is TCP? What is UDP? TCP is the method by which all transactions between IPv4 and IPv6 take place. Relies on a send and acknowledgement system. UDP (user datagram protocol) - a stateless connection between hosts, so there is no "acknowledgement" portion. In other words, data packets are sent to a destination without any verification they were received. Less overhead, but less reliable. What is ICMP? What uses it? intended for networking equipment such as routers, network switches, firewalls, and other devices to send error messages between themselves. It's used by ping and traceroute What does RFC 1918 describe? It describes the 5 ranges that determine how many hosts are available within each class? For RFC 1918 Class A, what is the range and number of hosts? 1 - 126; 16,777,214 For RFC 1918 Class B, what is the range and number of hosts? 128 - 191; 65,534 For RFC 1918 Class C, what is the range and number of hosts? 192 - 223; 254 For RFC 1918 Class D, what is the range and number of hosts? 224 - 239; Reserved for multicast For RFC 1918 Class E, what is the range and number of hosts? 240 - 254; Reserved for future use or research + development What it a network mask? Something that defines the logical network, or subnet, that indicates the start and end of IP addresses. What is the subnet mask for class A networks? 255.0.0.0/8 What is the subnet mask for class B networks? 255.255.0.0/16 What is the subnet mask for class C networks? 255.255.255.0/24 What class would a network belong to that contains 192 ? Class C What class would the following IP address belong to: 10.0.0.10 Class A What is a network gateway? the destination where network traffic does that has no other matching route or that is not intended for the local network. What is a broadcast address? How do you identify it? IP addr. used to broadcast messages to all hosts on a particular network. The last octet is 255. Ex) 192.168.0.255 is the broadcast addr. for 192.168.0.0/24 What is nmcli? NetworkManager command line interface, used for configuring network devices and their connection settings. What is the local loopback address for anything that uses the ICP/IP protocol? 127.0.0.1/8 What are the two ways a connection can get an IP address? Through DHCP and static IP assignment How would we use the ip command to add the IP address 192.168.122.76/24 to the device ens11? ip addr add 192.168.122.76/24 dev ens11 How can we take an interface called "ens11" down with the IP command? ip link set ens11 down How to we send TCP packets via the traceroute command? We specify the -T flag What is the modern equivalent of the netstat tool? ss, or socket statistics What is /etc/hosts used for? systems use this file for a computers hostname. the hostnamectl file will write a system's new hostname to this file. What does /etc/resolv.conf contain? contains the IP address of DNS name servers that the host will use for name resolution. For example, if you go to google.com. linux first checks if it's in /etc/hosts or /etc/hostname, and then since it's not in there, it uses DNS name server. Which command is used to query DNS servers for particular types of DNS records? dig What is the configuration that treats two or more network interfaces as a single network interface? Network bonding Describe the active-backup policy network bonding mode. Sets all interfaces to the backup state while one remains active. If the active goes down, another is taken from the backup state. Describe the XOR Policy network bonding mode. Selects an interface to transmit packages to based on the result of an XOR operation. Describe the IEEE 802.3ad policy network bonding mode. Creates aggregation groups for which included interfaces share the speed and duplex settings. Set this mode on server, and on switch, the ports understand they're working with this policy. Describe the adaptive transmit load balancing policy policy network bonding mode. ensures the outgoing traffic distribution is according to the load on each interface and that the current interface receives all incoming traffic. One interface receives all of the data. How would we create a bridged connection interface? How would we then assign network interfaces to the bridge? > brctl addbr br0 What does /sys contain? information about the system's hardware and kernel modules. no process info listed here. What is a mount point? When you take a partition or disk and mount it to a specific directory. What does /opt contain? Location used for optional software for 3rd party vendors. Which command shows a summary of swap usage on a system? swapon --summary In which directory are hard drives accessed? /mnt In which directory are sysadmin tools located? /sbin What does /var contain? files that vary in size, like log files and printer files What is the partition ID for the standard linux filesystem? 83 What is the partition ID for linux swap partitions? 82 What is the partition ID for Linux LVM volumes? 8e Which legacy command is used to create partitions of MBR DOS type? fdisk Which legacy command is used to create partitions of either MBR or GPT types? parted Which command is used to create the newer GPT partitions on a disk? gdisk Which 3 commands can be used to create a swap partition? fdisk, gdisk, parted Which command is used to format a partition to be used as swap space? How do you create a label with it? mkswap; use the -L flag After creating a swap partition, it disappears when the system is powered off. What do we need to do to have it persist? Edit the /etc/fstab file What partition does EFI need to use? FAT, or VFAT on a linux system How would we create an ext4 file system with label SRV on /dev/sda1? mkfs.ext4 -L SRV /dev/sda1 How do we display a filesystem's UUID? blkid What line would we add in /etc/fstab to mount /dev/sdb1 to /opt? LABEL=opt /opt ext4 defaults 1 2 In the mount command, what does the -o flag allow for? Provides filesystem independent mount options What are some examples of filesystem independent mount options "rw, noexec" which means the filesystem is readable/writable but not executable What command would we use to mount a CD ROM? "mount /root/install.iso -o ro,loop /media" specifying loop so it is continuously read What is the daemon that monitors paths, marks fails, and reactivates paths? multipathd Why are multiple routes to storage devices created? For redundancy. If the route selected fails, the multipath daemon finds anothe route to the host and monitors previous route so when it comes back up, it adds it again to the rotation. What is the "fsck" command and at what location is it configured? The filesystem check utility. Configured in /etc/fstab. What command is used for checking ext2, ext3, and ext4 filesystems? What command is used for creating ext2, ext3, and ext4 filesystems? e2fsck, mke2fs What utility is used to repair XFS filesystems? xfs_repair What command reorganizes data stored in blocks on an XFS filesystem? xfs_fsr What 3 commands can we use to display inode information? ls -i; df -i; du --inodes Which utility is used to convert files from one character encoding to another? iconv Where does "apt" read sources from? /etc/apt/sources.list
Using dpkg, how do we list out files installed for a specific package? dpkg -L What is the yellowdog updater? A package installed for RHEL, CentOS, and older Fedora that handles RPM package dependencies. Which package installer is used on Fedora linux? DNF What does a .rpm package contain? - The application or utility Where is the RPM database located? /var/lib/rpm Where are .so files found in linux? - /lib What file extension is used for statically linked libraries? .a Which file does the ldd command look at? /etc/ld.so.conf Which desktops do GTK+ include? GNOME and XFCE What desktop does Qt based have? KDE What is the X11 system? Core display server that provides protocol service for the X window system. List 3 X11 extensions. RandR, GLX, Xinerama
Where are X-Server configurations found? - /etc/X11/xorg.conf What is Wayland? What is the backwards compatibility tool for it? Replacement for X windows system. XWayland. What is the xhost command? An older/insecure method of allowing client systems the ability to display remote X11 windows. What does the xauth command do? Allows a user to edit and view security information that grants a user the ability to control remote X11 client windows. What is VNC? Virtual Network Computing, enables remote computer to control the graphical display of a remote system. What is the linux device manager? udev What does D-bus do? Sends data messages between applications, a conduit of information about what is going on in the system. Used to notify users when new hardware is attached. What commands do we use to display the following info: PCI devices, USB devices, system processor info, block devices? lspci, lsusb, lscpu, lsblk What does the lpd toolset do? Adds/removes printers, enables and disables them, manages print jobs. How do we view all print queues? lpq -a How do we view and edit a user's cron table file? crontab How do we remove a crontab file for the user Kenny? crontab -r -u Kenny Which directory contains cron jobs for the whole system? /etc/cron.d What is the difference between "cron" and "at"? Cron is for recurring jobs while at is used for one-off jobs to be run. Once we install the "at" package, how do we enable and start it? - systemctl start atd.service How would we make an "at" job that will run 5 minutes from now? at now +5 minutes How do we set up an "at" job with a specific time, say 4:00 AM tomorrow? at 4:00 AM tomorrow rm /root/notes.txt How can we specify an "at" job that runs a script /root/program.sh at 10:15PM on October 8? at -f /root/program.sh 10:15 PM Oct 8 What are the two types of Systemd timers and what parameters does each have? - Monotonic (OnBootSec,OnActiveSec) What are the three sections of a systemd timer file? Unit, Timer, and Install What happens if we try to copy a file to a location and it has the same file name? The copy command won't let us perform the operation. What symbol is used in file globbing to match a single character? How would you use this to find a .txt file with 4 characters? ?; ????.txt What file globbing expression would we use to search for a file that has any of the three characters: a,b,c ? [abc] What would we use to search for some file that begins with either a capital or lowercase "p" and ends in an extension .csv? [Pp]*.csv What file globbing regex would match and of the characters of a file except these: a,b,c ? [^abc] How would you use grep to search for a file where the first letter is g, the second is any character, and the third letter is m? grep g.m Which grep regex searches the beginning of a line? How would we use this to return lines where the first 3 letters of 'rpc'? grep ^rpc passwd Which flag for grep makes character regexes case insensitive? -i Which character searches the end of the line in a regex expression? How would we use this to print out any lines that contain "bash" at the end? grep bash$ passwd What does the egrep command do? What is it equivalent to? Searches a specified file line by line, returning lines that contain a pattern matching a given regular expression. Grep -E.
What is fgrep? Utility that searches based on strings rather than patterns and uses file globbing instead of regular expressions. What is a symbolic link? Acts as shortcuts files or folders on other operating systems. It's like an alias. How do you create a soft link? ln -s What happens if you make changes to the symbolic link? It modifies the original file. How do we look for a file called "mc.sh" in our current directory? find . -name mc.sh Why is the "find" command computationally expensive? Relies on CPU usage extensively instead of an external database since it searches through computer each time you use it. How would we find a file that has been modified within the last 24 hours? find . -ctime 1 How would we use the "find" command to get rid of empty files? find . -empty -type f -exec rm -f {};
What are the file handles associated with the following: standard error, standard in, standard out? 2, 0, 1 How would we redirect standard error from the script internet.sh to error.log? internet.sh 2> error.log How would we send standard error from internet.sh to standard out? internet.sh 2>&1 | less Which command searches a local database of files and folders looking for items that match the search criteria? locate How do we update the database that "locate" uses? updatedb How do we find the location for a particular command? whereis Which command reads data from stdin and writes it to stdout and files? tee What does "xargs" do? Used to take the standard output of one command and use it as standard input on another. How would we use the "find" command to remove empty test files for us? find test/ -empty | xargs rm -f Why is xargs faster than -exec? It creates sublists and gives the ability to act on all files in one fell swoop. How would we use the "dd" command to put boot.img on /dev/sdc? dd if=boot.img of=/dev/sdc How would we use the "dd" command to back up the master boot record /dev/xvda of size 512 bytes? dd if=/dev/xvda of=/tmp/mbr.img bs=512 count=1 What do the following switches do for tar: -c, -f, -t, -x ? -c tells us we are CREATING an archive, -f tells tar we are createing a name for our archive, -t informs tar we want to see the contents of the tarball, -x opens the tarball back up and copies everything inside the archive back to filesystem What switch tells tar we are going to compress an archive using gzip? -z How would we use tar to compress a folder called content-lpic-1/ into the tarball content-bak.tgz ? tar -czf content-bak.tgz content-lpic-1/ What switch would we use in "tar" to utilize bzip2 for compression? -j Which command extracts .bz2 compressed files? bunzip2 Which command is used to extract .gz files? gunzip Where does the "init" program read configuration settings? /etc/inittab What does init level 0 do? runs scripts that stops and powers off the system What does init level 1 do? Root user is the only user allowed to login to this system. What does init level 2 do? No remote filesystems, no networking, but multiple users can login. What does init level 3 do? No remote filesystems, multiple users can login. What does init level 4 do? Used in the case the admin wants to set up a custom environment. What does init level 5 do? No remote filesystems, multiple users can login, and a graphical desktop is running. What does the redhat service tool "chkconfig" do? Sets queries and runlevel settings for services How would we use the chkconfig command to prevent the bluetooth command from starting at runlevel 3? chkconfig --level 3 bluetooth off What is the redhat textual user interface for managing services based on runlevel? ntsysv How does upstart differ from init? Upstart offers asynchoronous starting of services, which decreases bootup time. How do init and upstart differ from systemd? Init and upstart rely on bash shell scripts/ systemd does not. What is the location of the unit files provided by the package installation for systemd? /usr/lib/systemd/system What is the location of the unit files for systemd that are safe to be edited by system admins? /etc/systemd/system What command can we use to view all unit files on a system? systemctl list-unit-files In a systemd .unit file, what does "Requires" variable have? The unit that is activated, in the form of a .target file. When the kernel boot up process uses systemd, what is /sbin/init symbolically linked to? /lib/systemd/systemd Describe the 3 main locations for systemd unit files. - /usr/lib/systemd/system - provided by package installations What are the two main methods of creating a custom unit file? -
copying an existing unit file from /etc/lib64/systemd/system to /etc/systemd/system and editing the file Which command creates the necessary directory structure etc. for unit files? systemctl edit --full <unit> What is the purpose of a systemd target? Serves as a unit that syncs other units when the computer boots or changes state. How would we show all the unit files for some target? systemctl list-unit-files -t <target> Using systemctl, how would we change the running state of the system from the current target to a different target?
systemctl isolate <target> What command enables a service unit to start at system boot up by creating a symbolic link? systemctl enable <daemon.service> What is the timer unit file meant to be a replacement for? atd and cron systems What corresponding file do you need for a .timer file? .service file List the two types of timer units and their paramters Monotonic (OnBootSec,OnActiveSec) and Realtime (OnCalendar) In which section of the timer file do you put the corresponding .target file? Under the [Install] section, you'd put it equal to the parameter "WantedBy" What is the process ID for systemd and when does it start? PID1, which starts after the kernel finishes booting. Which PID corresponds to user space? How about kernel space? PID1 and corresponding children processes are "user-space". PID2 and corresponding child processes are "kernel-space". How do we list processes in current shell only? Execute "ps" without any flags. Which switch on ps shows processes running for all users? ps -e Which command provides interactive realtime viewing of all processes? top Which command let's you view how long the system has been up, how many users are logged in, and CPU load average? uptime What does the free command do? View used and available memory and swap space. What is signal 15? What is signal 9? This is the sigterm signal, which is used by the "kill" command. This is the sigkill signal. What happens when you kill a process? It also kills all of the children processes. How would we send a sigkill message to PID 2407? sudo kill -9 2407 Which command is used to monitor the output of processes at specified intervals? watch -n What is the linux modern terminal manager that is like "screen"? How would we use it to reattach back to some session? tmux attach-session -t 0 What is nohup? Some command preceded by this one receives a signal of 1 (NOHUP), so that if the terminal window closes, the process will still run as the login session is not terminated. What commands are used to put a job in the foreground or background? fg, bg What is DNS and what is the associated port? Used to translate domain names into IP addresses; UDP/TCP 53 What packages provide DNS? BIND, dnsmasq, Unbound What port does NTP use? UDP 123 Which services provide NTP? ntpd, chronyd, systemd-timesyncd What does DHCP do? What ports is it associated with? Provides automatically assigned IP addresses to a client on a network; UDP 67,68 Which services provide DHCP? dhcpd, dnsmasq List the ports for LDAP/LDAPS. TCP 389; TCP 636 What is the port associated with certificate authority servers? TCP 443 What is server clustering? Practice of running more that one server that is configured to provide the same service so if one fails the other can continue to provide it. What is the port for syslog? UDP 514 What is the port for secure syslog? TCP 6514 Which packages provide logging services? syslog-ng, rsyslog, systemd-journald What are the ports for SNMP? UDP 161,162 What are the ports for SNMP over TLS? 10161, 10162 Which packages provide monitoring services? SNMP, Nagios, Munin, Zabbix, Monit Which packages provide proxy server services? Squid, Varnish, Apache, Nginx Which packages provide file server services? Samba, NFS What are the ports for Samba? TCP 137,445 What are the ports for NFS? TCP/UDP 111,2049 What is the port for SMTP? TCP 25 What is the port for POP3? TCP 110 What is the port for IMAP? TCP 143 What packages provide email server services? Sendmail, Postfix, Dovecot What is the port for CUPS? TCP 631 What is the port for MySQL? TCP 3306 What is the port for PostgreSQL? TCP 5432
When looking at file permissions, what does an "s" in place of the "x" permission mean for a group? This assigns group ownership to files and is useful for shared groups or directories. What is the sticky bit? This is a "t" in place of the "x" in the "others" section of permissions and only allows the creator of a file to remove the file. How would you set the stuck bit on /srv/sticky with rwx permissions on all 3 sections? chmod 1777 /srv/sticky What is umask? This is the default masking value that gets taken away from the default permissions of files and directories in a system. What are the default permissions for directories? 777 What are the default permissions for files? 666 If the umask is 0002, what would the default permissions for directories become? 777 -> 775 Where would we modify the umask for the entire system? /etc/bashrc Using the umask command, how would we set the user to have full permissions, but the group to have none? umask u=rwx,g=,o= which results in umask of 0077 Which command shows you the file access control list? getfacl How would we use the "setfacl" so that jimmy is the only user who can read file1 ? setfacl -m u:jimmy:r file1 What is the access vector cache? This is a cache of all denies/allows that SELinux has done. In SELinux, how would we change from permissive mode to enforcing mode? sudo setenforce 1 How would we enable the SE boolean for httpd_enable_homedirs? sudo setsebool -P httpd_enable_homedirs Where are SELinux policy files located? /etc/selinux What does SELinux permissive mode do? How do we set it? "setenforce 0" will log exceptions but does not perform denials How would we change the AppArmor profile to complain mode? sudo aa-complain /sbin/dhclient How would we create a new AppArmor profile for Xtightvnc? sudo aa-genprof Xtightvnc What line would we add in the /etc/sudoers file so that user "example" could run "sudoedit" on "/etc/pam.d/password-auth-ac" ? example ALL = sudoedit /etc/pam.d/password-auth-ac How would we add user "example" to the group "passmanagers" ? usermod -a -G passmanagers example What character do you need to put in /etc/sudoers when specifying a group? % What is PAM? Pluggable Authentication Module - common authentication mechanism on linux system with a single configuration location. What is SSSD? System Security Services Daemon provides access to local or networked identity and authentication stores. Used for caching credentials. After we login to some machine using ssh, where will we see a new entry? /.ssh/known_hosts How do we create a private/public ssh key? ssh-keygen How would we copy a generated ssh id into ? ssh-copy-id How would we allow the IP addresses {3.17.167.1, 172.31.100.21} to ssh into our system and deny all others? Edit /etc/hosts.allow to have the line "sshd : 3.17.167.1,172.31.100.21" and edit /etc/hosts.deny to have "sshd : ALL" Which command allows you to see which sudo terminal you're in? tty How does transport mode differ from tunnel mode? In transport mode, data is encrypted, but headers are not encrypted. In tunnel mode, both headers and the data are encrypted. Transport mode is used in remote access VPNs. Tunnel mode is used in site to site VPNs. What layer is IPSec in? Layer 3. Not application dependent. What layer is VPN using SSL/TLS on? It's on the application layer. It is application dependent because it is two applications talking to one another. What can you use instead of OpenVPN? DTLS, Datagram Transport Layer Security, which uses UDP and has less latency. Give an example of MFA. MFA is comprised of a minimum of two factors: something you know (password), something you have (token), something you are (biometrics) What is RADIUS? Remote Access Dial-In User Service. Internet protocol that provides authentication, authorization, and accounting services. It provides a central source for AAA services. What is TACACS? How does it differ from RADIUS? Terminal Access Controller Access-Control System provides AAA services, but it scalable and more secure than RADIUS.
List 4 common kerberos commands. kinit (generates ticket), kpassword (sets kerberos password), klist (lists tickets user has), kdestroy (destroys current ticket) List some things you should do when designing secure systems. Don't use shared IDs. Use a chrooted jail. Separate application from OS data using disk partitions. Discourage USB devices. Use disk encryption. Disable ctrl+alt+del. Add banners. How can we utilize ports to make a system more secure? We can make sure that services are not running on their default ports. Which is better when it comes to securing systems: password authencation or PKI? PKI Which command shows us all of the TCP ports listening on the machine? netstat -plnt What 3 methods can we use to partition and isolate services? Using a chroot jail for services, enforcing context permissions, ensuring logging is enabled. What file would we edit to allow only cloud_user to remotely login to a system? We'd edit sshd_config and add the following: AllowUsers cloud_user Where do authentication attempts get logged at? /var/log/auth.log Which directory contains configuration for log files? /etc/logrotate.d Where is remote logging configured? /etc/rsyslog.conf Which command shows you who's logged in? last Where is the journalctl daemon configured at? /etc/systemd/journald.conf Which command lets you look at the firewalls on linux? iptables -nL How does a stateless firewall work? It provides single packet filtering and no introspection. It doesn't know about the packet in front of it or behind it. Simply accepts IPs from a certain range and sends it to some destination. How do you know you're using a stateful firewall? When you see: RELATED,ESTABLISHED Which layer do application layer firewalls operate at? Layer 7. Which 4 things are ACL filters based on? Source IP, destination IP, source and destination port TCP/UDP, and the protocol TCP/UDP How can we manage ACLs? Using iptables Which file would we edit to enable IP forwarding for IPv4? We'd uncomment the line "net.ipv4.ip_forward=1" in sysctl.conf How would we add ourselves to the IP set called 80_allow? ipset add 80_allow <MY_IP> What monitors servers and updates firewall rules to reject certain IP addresses? fail2ban What are the trusted ports? 0 - 1023 Type the command that uses the uncomplicated firewall tool to allow mysql. ufw allow mysql How would we use ufw to deny all incoming traffic. sudo ufw default deny incoming Which command would we use to identify which zone is the default zone in the firewall? sudo firewall-cmd --get-default-zone Type the two commands you'd use to archive and restore some tar. > tar -cvf backup.tar What is CPIO and how does it work? It's a utility used to create archive files and can take stdin. For example we can do "ls | cpio -ov archive.cpio" How to differential backups work? They contain the changes since the last full backup occurred. Restoration involves restoring the full backup, and then the differential. What are advantages and disadvantages of differential backups? They are faster to create, but slow down as more and more differentials are taken since more backups needs to be restored since the last backup. How does incremental backup work? Only the changes since the last incremental backup are taken. Restoration involves restoring the full backup and then incrementing it forward to the latest change set. What are advantages and disadvantages to incremental backups? These backups are faster, but restoration is more complicated. What is rsync used for? What is it implemented over. Copying files to remote and local filesystems; ssh or the rsyncd daemon. What command would we use to get the MD5 hash for some file? md5sum What command can we use to get information about our ethernet card? lspci | grep -i ethernet What command can we use to see if there are ports that are open that we can use? nmap What command would we use to get round-trip time? traceroute How would we use the netstat command to see if a server is listening to the ssh port? netstat -an | grep ssh What command replaced netstat? ss Which command shows us the routing table that our kernel is using? route Which command shows us hardware addresses associated with certain IPs? arp Which command shows you the TX and RX totals and the rates for each of them. iftop Which command is used to inspect packet drop/timeout? mtr What two command could we use to look at the A-record for google.com ? dig or nslookup Which command gives us registrant information for a domain name? whois What command would we use to initialize the physical volumes /dev/sdb and /dev/sdc? pvcreate /dev/sdb /dev/sdc Which command would we use to create some volume group called vg1 comprised of the physical volumes /dev/sdb and /dev/sdc? vgcreate vg1 /dev/sdb /dev/sdc How would we greate a 9G logical colume on the volume group vg1? lvcreate -n combined_vol -L 9G vg1 After creating a physical volume group and mounting some directory to the physical drive, how would we update everything? Use partprobe Which command shows us how much drive space there is? df -h Which command is used to test disk latency? ioping Explain the IO Scheduler "deadline" mode. This is a first in, first out mode that has both a read and write queue. Explain the IO Scheduler "noop" mode. Doesn't sort the requests. When you're using non-volatile RAM, you want to use noop since it doesn't slow things down. Explain the IO Scheduler "[cfq]" mode. Each process gets its own time slice and the scheduler looks at each time slice. This is a round robin approach. What file needs to be edited to change the IO Scheduler mode? /sys/block/sda/queue/scheduler Which command shows us the load average of a machine in addition to how long it's been running? uptime What command could we use to see what flags are set and running in the kernel? sysctl -a | grep kernel How would we put swap space on /dev/sdb1? > mkswap -c /dev/sdb1 Which command is similar to "free" but gives us processor information as well as free memory space? vmstat What's the best way to prevent the "out of memory killer" from going through processes it doesn't need and killing them? Create swap space and offload memory there. What is the memory referred to that is assigned to a swap device and is used to cache filesystem data? Buffer If we wanted to recover a lost password, what key would we hit at the GRUB boot menu 'e' If we wanted to recover a lost password, what would we enter after root=UUID info? rw init=/bin/bash What command is used to see ALL processes? ps ax List the 5 states that a process can be in. Zombie, Uninterruptible sleep, interruptible sleep, running, stopped/paused (T) When running "ps -l", what does NI stand for? Nice - it's the priority of the process where a lower value is higher priority. What is the highest "nice" value? -20 How would we change the "nice" value to 15 for some process with ID 3701? sudo renice -n -15 3701 What sort of levels of niceness should a cron job be operating at? Lower levels Which command is used to see which process is using the most resources? top Which command can show you how long a process has been active and how long it takes to run? time Which command can tell us which process has which files open? lsof What might be the issue if you can't delete a folder in your home directory? Might be directory above you. Run "lsattr ../" and see if it has an immutable flag. How can we change a directory attribute from immutable to mutable? chattr -i ../example/ What are server access issues typically caused by? VPN Where can we get logs with information about authentication on some machine? /var/log/secure If there is space left on the device, but you apparently can't create another file, what might be the problem? There may not be enough inodes. Increase space. If you try creating a file and get an error "disk quota exceeded", what might this mean? You've exceeded the limit of files that can reside on the disk. If you have free space and have not exceeded the inode count, what might be the issue when trying to create a file? The directory is immutable. What command would we use to get Access Vector Cache denies from the SELinux audit log? sealert -a /var/log/audit/audit.log In an SELinux AVC log error, what two things should you check to see if they align? The scontext (source context) and the tcontext (target context) What might be the issue if we can't run basic commands such as "ls" and "clear" ? The user might have added something to their PATH variable, but it is incorrect/they didn't put the whole path. What did SATA replace? IDE (Integrated Device Electronics) What is an HBA? Where does it go? Host Bus Adapter - hardware device that interfaces with external or internal devices. Also serves as a storage adapter. It clicks into the motherboard. What is RAID1? Mirroring
What is RAID0? Striping If you verified that a device is connected in /sys but you're still having issues, what should you check? /etc/fstab for incorrect information and typos What two commands are used to make sure you have enough space free and make sure you have enough inodes? >
df -h What things would you want to check when troubleshooting firewall issues? Restrictive ACLs, blocked ports, and blocked protocols. If something you're using on your machine has a TCP wrapper, where will it look to deny certain hosts? deny.hosts What sort of accounts have /sbin/nologin? Service accoutns created for applications. If we are on CentOS, how can we check the dependencies of some package, such as nginx? yum deplist nginx How can you differentiate between shell variables and environment variables? Env variables are uppercase. Shell are not. Shell variables are set on each child. Environment variables are set on the workspace and the children inherit from these parents. What are exit codes? Integers that get passed back to the parent when a process has completed. What can we use to redirect standard error? >&2 In a bash script, what do we enclose conditionals inside of? [] In a bash script, what would we put after an "if" statement to execute code if the condition is met? then What ends a case statement in a bash script? ;; In a bash script, if we wanted to declare some variable called "var" to be the first argument a user provided when running the script, how would we do this? var=$1 What would a "for" statement look like in a bash script if we wanted to iterate from 1 to 5? for i in {1..5} How can you create positional parameters inside of a script? Using "set", for example, "set -- first1 second1 third1" In git, what does HEAD point to? The current directory of the branch you're in. In git, where do you store any scripts that need to be run when a commit is made? hooks/ Where are commits stored in git? objects/ What distinguishes agent vs. agentless scenarios? Agentless management requires no software installed on target machine. Agent management requires software to be installed on the target machine with elevated privilege. What is an example of agentless software and agent software? Ansible is agentless. Puppet uses agent management. What can inventory reports be used for? Ensures that the commands run on the machines in a system infrastructure are the correct ones. What does infrastructure as code refer to? The process by which all of the objects on an infrastructure are described in code in such a way that they can be reproduced by running that code. What components does infrastructure as code include? Deploying new assets, configuring assets, deploying and managing applications + databases, deploying and managing monitoring and patching. What are two reasons infrastructure as code might be important? Infrastructure resilience and ability to be stable when a hardware issue occurs. Also useful for scaling out when more resources are needed. What are two good examples of infrastructure as code? Docker and Vagrant How do you differentiate automation and orchestration? Automation is the steps taken to build infrastructure. Orchestration is the management of automation to achieve a deployed infrastructure. In automated configuration management, what do the target and master servers contain? Target server has the files to be tracked. Master server contains the manifests for the tracked files. Sets with similar terms
Client Server63 terms Dana_Esmeralda CompTIA A+ 220-902 Practice201 terms kevan_brenay Lesson 1: Installing Servers115 terms Keri_Gatschene CHFI - Chapter 6 (Operating System Forensics)114 terms athenadaniel Sets found in the same folderCompTIA Linux+ XK0-004 Exam Prep161 terms lsmithjr7 Final Review249 terms deadoceans 1 Boot Process Concepts21 terms deadoceans 2 Install, Manage, Config, Monitor Kernel Modules12 terms deadoceans Other sets by this creatorExam Questions Review37 terms deadoceans Writing Words34 terms deadoceans Chapter 3 Information Gathering20 terms deadoceans Chapter 2 Planning and Scoping Penetration Tests R…20 terms deadoceans Verified questionsCOMPUTER SCIENCE Suppose that we have a linear program that is not in standard form. We could produce the dual by first converting it to standard form, and then taking the dual. It would be more convenient, however, to be able to produce the dual directly. Explain how we can directly take the dual of an arbitrary linear program. Verified answer COMPUTER SCIENCE Give context-free grammars generating the following languages. $^A{a}$. The set of strings over the alphabet {a,b} with more a’s than b’s, b. The complement of the language $\left\{\mathrm{a}^{n} \mathrm{b}^{n} | n \geq 0\right\}$, $^A{c}$. $\left\{w \# x | w^{\mathcal{R}}\right.$ is a substring of x for w, $\left.x \in\{0,1\}^{*}\right\}$. d. $\left\{x_{1} \# x_{2} \# \cdots \# x_{k} | k \geq 1\right.$, each $x_{i} \in\{\mathrm{a}, \mathrm{b}\}^{*}$, and for some i and j, $\left.x_{i}=x_{j}^{\mathcal{R}}\right\}$. Verified answer
COMPUTER SCIENCE We talked about the trade-off between using sequential search on an unsorted list as opposed to sorting the list and then using binary search. If the list size is n = 100,000, about how many worst-case searches must be done before the second alternative is better in terms of number of comparisons? (Hint: Let p represent the number of searches done.) Verified answer COMPUTER SCIENCE True/False. A reference variable that does not currently point to an object is called a null reference. Verified answer Recommended textbook solutions Information Technology Project Management: Providing Measurable Organizational Value5th EditionJack T. Marchewka 346 solutions Service Management: Operations, Strategy, and Information Technology7th EditionJames Fitzsimmons, Mona Fitzsimmons 103 solutions
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