8-10 Flashcards
BIND stands for
Berkley Internet Name Domain
What is the default Linux ping packet size?
64 bytes
T/F: The Linux whois command will perform an information lookup on an IP or domain name.
True
T/F: The HTML protocol uses the HTTP programming language across the WWW.
False
The _________ file stores user passwords.
/etc/shadow
T/F: Point to Point networks use dedicated connections and are typically costly.
True
Many services use the Linux _______ service (TPC 111) which allows secure client/server inter-comms.
RPC
What TCP port does ftp utilize?
21
A FQDN is broken up into 2 basic parts. What are they?
domain name
hostname
What two distinct parts are IP addresses are broken up into?
network
host
What protocol does ping utilize?
ICMP
T/F: ftp, http, and https, are all types of internet resources accessible from a web browser.
True
What Linux command can be used to display the local running and listening network services?
netstat
It is mostly used for scanning port mappings on the local machine, not services.
T/F: The root user can use telnet to log into a remote Linux server for management purposes.
False
What works at OSI layer 4? (Protocol)
TCP/UDP
What is the purpose of the Linux host and dig commands?
name to IP lookups
IP to name lookups
What are the two methods of assigning IP addressing to client devices on a network?
Static
DHCP
The ______ file contains services and their common TCP and UDP ports.
/etc/services
What TCP port does telnet utilize?
23
The military _____ network was the beginning of the internet.
ARPANet
There are _____ TCP ports.
65,535
What Linux service created a centralized network database of user credentials?
NIS
(Network Information Service)
Whats the default SN mask for a class C address?
255.255.255.0
What Linux command will display the known MAC address to IP address associations?
arp
What ftp command is used to upload a file?
put
Which one of the below is a service designed for the transfer of files across a network?
ftp
A web browser and a web server are an example of a client/server environment.
True
What command scans a remote system for open network services?
nmap
URL stands for:
Uniform resource locator
WWW stemmed from protocols created when?
1991
What breaks up an IP address into two distinct parts?
Subnet mask
To enable a systemd service or target, the root user can use the ln command from /etc/systemd to /lib/system.
False
The MBR resides in the first 512 bytes of a hard disk.
True
What runlevel is graphical mode?
5
What runlevel is multi-user mode?
3 (2 through 4 actually)
What runlevel is reboot?
6
What runlevel is shutdown?
0
What runlevel is single user mode?
1 (duh)
What is a valid method to discovering a user’s ID number?
the id command
What folder is a recue filesystem mounted to during a rescue attempt?
/mnt/sysroot
The su command stands for
substitute user
What is the r00t users ID number?
0
T/F: System units have wants and requirements which are really just dependencies.
True
The ______ command allows the root user to assign specific admin command to certain users.
sudo
What command can make a bit for bit copy of the HD?
dd
What command will display support files and drives needed by a program or command?
ldd
Only _____ can exit chroot.
root
Members of the wheel group have extended permissions beyond regular user permissions.
True
What systemctl option can dynamically (temporarily) change the runlevel environment?
Isolate
Temporary, does not survive a reboot.
systemctl isolate graphical.target
(graphical environment)
systemctl isolate multi-user.target
(text mode)
What is the predecessor to systemd?
initd
What command diplays the HD partition table?
fdisk
What does the following command do?
dd if=/dev/sda of=/bkup/mbr.img bs=512….
Makes a backup copy of the /dev/sda MBR
of= is actually the destination of the backup.
Users can be assigned additional permissions by adding them to a secondary group.
True
Located in /etc/group
What option with the sudo command will display a users elevated privileges?
-l
sudo -l test.user
What does the below comand do? (to what environment)
ln -sf …./multi-user.target /etc/…./default.target
Sets the server to boot in text mode. If it were graphical, it would be /graphical.target instead.
What command can change a users account expiration?
chage
An _____ sets limits on what networked systems can access given network services.
ACL
What does the below command do?
chroot /mnt/USB
Changes the root filesystem to /mnt/USB
What is the default setting for SELinux?
Enforcing
What does PAM stand for?
Pluggable Authentication Modules
List the order of the DHCP proccess.
Discover
Offer
Request
Acknowledge
What does DIG stand for?
Domain information groper
Most services end in the letter:
d
What web service has the most market share?
NginX
What does VSFTPD stand for?
Very Secure FTP Daemon
What is the PID number of the systemd service?
1
What service (or target) is “required” to run the graphical desktop?
multi-user.target
This is the value of “Requires=” displayed with the systemctl command to determine the requirements of graphical.target.
Needs text before it can boot to graphical.
What does the “dd” command mean or stand for?
data dump
What Linux command sets the default permissions on any new file or directory?
umask
It lists permissions that are not set if executed without options.
Example output:
0022
What is the most restrictive implementation of SELinux policies?
MLS
MultiLevel Security for server
Requires selinux-policy-mls
The other two policies are Targeted (default) and Minimum.
What common Linux service is typically run in a chroot environment?
named
It a DNS service that prevents access outside the fake root directory.
What file can be used to prevent all regular users from logging into the Linux server?
/etc/nologin
Which one of the listed should not have a DHCP address?
routers
What is the name of the main DHCP servers configuration file?
dhcpd.conf (watch out for the extra d, should only have 2!)
What manually installed program opens the SELinux GUI boolean?
system-config-selinux
Installed from policycoreutils-gui
How does PAM work?
It validates that the user exists in /etc/passwd, and validates the password in /etc/shadow.
PAM checks authorization ______ type.
Module
IT checks if files and file configs exist depending on the particular process.
T/F: PAM does not show a reason why authentication has failed.
True
What file details where root can directly login from?
/etc/securetty
If the file does not exist (default), root can login from anywhere
What command and option will lock an account?
passwd -l [user]
This will place “!!” in the shadow file.
The _____ group has elevated permissions when using “sudo”.
wheel
What single user mode for?
Maintenance as the root user.
T/F: Always use “-“ and never su more than one user.
True
What file contains users and what commands they are allowed to execute with root permissions?
/etc/sudoers
When creating sudo commands for users, should you use the full or relative path?
Always full path
Syntax:
user host_computer=(run as) command(s) with full path
“run as” assumes the root user if not present.
What is the “.target” systemd unit type?
A multitude of services grouped together as one.
What are the two most important folders related to systemd and services?
/etc/systemd/system
/usr/lib/systemd/system
/etc/systemd/system contains links to services in /usr/lib/systemd/system. If the links in /etc/… are aqua, they will start at boot.
“systemctl enable [service]” will create the link automatically. The other option is “ln- sf” (symbolic & soft).
Not only does /usr/lib/systemd/system contain links originating from /ect/systemd, it also contains files from _____ installed programs.
manually
Ex: dnf, rpm
What option, when run with the systemctl command, will display loaded services, both failed and active?
- -all
systemctl - -all
After a “systemctl start”, you should always do a systemctl _____.
status
What does pgrep do?
Displays processes owned by the user (pgrep -u [user]).
What command will format partitions?
mkfs
stands for “make filesystem”
