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40 Cards in this Set
- Front
- Back
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What is the first line of a bash script?
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#!/bin/bash
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In Chmod what do all of the options mean?
chmod augo +wrx a = u = g = o = w = r = x = |
a = all users
u = user g = group o = other w = write r = read x = executable |
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Using grep find the lines that contain “0304 2013" in the file myfile.txt and append it to newfile.txt
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grep "0304 2013" myfile.txt >> newfile.txt
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Use awk to print the first and tenth field delimitated by | in the file myfile.txt
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awk -F "|" '{print $1,$10}' myfile.txt
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Open crontab, add a program myreport to run at 3:47 every Wednesday the 14th of August.
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crontab -e
47 3 14 8 3 myreport |
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Open crontab, add a program "myreport" that runs at 8:00am/pm every thursday.
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crontab -e
0 8,20 * * 4 myreport |
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Use tail to continue to display the last lines
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tail -f
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How to manage users that can run crontab.
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/etc/cron.allow
/etc/cron.deny |
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What does DNS stand for?
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Domain Name Services
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What does BIND stand for?
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Berkley Internet Name Domain
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What port does DNS run on?
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53
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What does DNS do?
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Maps IP's to hostnames and hostnames to IP's
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What file do you edit to make 141.219.16.30 your DNS server?
What do you add to this file? What if you want to add srv01 as a DNS server? |
/etc/resolv.conf
nameserver 141.219.16.30 nameserver srv01 |
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Where do you configure the zone information?
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/etc/named.conf
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Where is the zone file/record created?
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/var/named
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In /var/named what are these kinds of records?
MX = CNAME = A = NS = SOA = TXT = |
MX = mail server
CNAME = alias A = IPv4 address NS= name server SOA = Start of Authority TXT = descriptions |
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How/Where do you change the order of priority for DNS, files, and NIS?
Put DNS server first, then files, then NIS |
/etc/nsswitch.conf
hosts: dns files nis |
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How do you set your DNS nameservers on the interface?
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/etc/sysconfig/network-scripts/ifcfg-eth0
DNS1= srv01 DNS2= 141.219.16.0 |
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Where to manually do IP to hostname mapping?
Map 172.16.2.8 to srv01 |
/etc/hosts
172.16.2.8 srv01 |
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How would you provide IP/host names in a small network using NIS
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vi /etc/nsswitch.conf
hosts: nis files Then /etc/hosts has to be converted into an NIS database file |
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What does ICANN stand for and what does it do?
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Internet Corporation for Assigning Names and Networks
This delegates to root domains and top level domains. |
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What is a zone?
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An administrative space.
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What is a chroot jail?
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This allows you to prevent ordinary users from accessing the root directory. It creates a subdirectory and sections it off.
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In the named.conf file what does ____ do?
listen on allow query allow recursion allow-transfer notify |
listen on- the port that DNS is going to be on
allow query- who is allowed to query the DNS server allow recursion- who is allowed to make recursive queries to this server allow-transfer- what slaves are allowed to transfer slave files notify- notifies slave servers |
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What does the effect of lowering the DNS ttl have?
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Shortens the time the DNS cache lives and will increase load on DNS server because it will have to always look for information.
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How to see what files are being shared from srv01 while on the client machine?
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showmount -e srv01
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Which command line lists the currently mounted NFS directories?
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df -t nfs
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Command to mount /home from server plum to /plum.home on local server.
Unmount it |
mount plum:/home /plum.home
umount /home |
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From a server, how would you allow readonly access to /opt for any system in example.com?
Where would you place this line? |
In /etc/exports
/opt *.example.com(ro,no_subtree_check) |
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root_squash and all_squash map users to UID ___?
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65534
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What does nosuid do?
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This stops programs from running as the root user. This is a security threat.
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Difference between passwd and yppasswd
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Passwd changes password on local machine
Yppasswd changes password on NIS server |
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Why does /etc/passwd file need two NIS maps
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You can look things up by username and uid
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How can you determine if a working directory is the home directory of an NIS user?
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ypcat passwd | grep $(pwd)
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What kind of DNS record will be returned when a Web browser resolves the domain part of a URL?
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A DNS record type
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What are MX resource records for?
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Mail exchange server, they hold the name of the mail server
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Set system to use local DNS server at 192.168.1.254 or ISP DNS at 1.2.3.4
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vi /etc/resolv.conf
nameserver 192.168.1.254 nameserver 1.2.3.4 |
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How to instruct DNS server to respond to queries only from 137.44*
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Edit /etc/named.conf
Add allow-query {137.44.0.0/16} |
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Which part of DNS is most vulnerable to an attack from a malicious user and why?
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Primary master server because requests are recursive here and you could implement a DoS attack
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Outline a method to make DNS support encryption.
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You could use TSIGs to make sure the master/slave server are actually the correct server.
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