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Operating Systems FINAL
OS FINAL
82
Computer Networking
Undergraduate 1
12/12/2011

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Term
[ifconfig]
Definition
lets you configure your interface
Term
[ifstatus]
Definition
shows the status of network interfaces
Term
Command to toggle Interfaces On or OFF
Definition
[ifup] and [ifdown]
Term
[route]
Definition
lets you see routing table or create static routes
Term
[ip]
Definition
intended to replace ifconfig, but not very popular
Term
]netcat]
Definition
"swiss army knife" Does a lot but sucks at doing it all
Term
[netstat]
Definition
shows all connections to your machine
Term
[netstat -r]
Definition
shows routing table
Term
[netstat -i]
Definition
shows info about your network interface
Term
tcpdump
Definition
protocol analyzer "sniffer” text based. runs in shell, monitors network and reports every packet that it sees. Like Wireshark
Term
ethereal
Definition
similar to TCPdump: diagnosis tool that lets you analyze data packets through a network interface. Like Wireshark.
Term
ZONE FILE RECORD TYPES
Definition
SOA NS MX A PTR CNAME
Term
ZoneFile Record type: SOA
Definition
Start of Authority: defines the Domain
Term
ZoneFile Record type: NS
Definition
Name Server: Name of one of the DNS servers for this domain
Term
ZoneFile Record type: MX
Definition
Mail Exchanger: name and priority of a mail server for this domain
Term
ZoneFile Record type: A
Definition
Address: IP address of a computer
Term
ZoneFile Record type: PTR
Definition
Pointer: Name of a computer
Term
ZoneFile Record type: CNAME
Definition
Canonical Name: alias name for a computer
Term
Zone File
Definition
Holds the address and hostname information within that domain.
Term
Zone Transfer
Definition
the way to zone file is distributed to the other servers. Uses a serial number at the top of the zone file, and Name servers compare it to decide when to update.
Term
resolv.conf
Definition
shows who your names servers are, also adds the search path “.byui.edu” search path is appended
Term
nsswitch.conf
Definition
you tell Linux where it should go to resolve names, if it says [ files dns ] then it will go to local host file first, then to DNS, order matters.
Term
[host]
Definition
test your name servers; replaced [nslookup]
Term
[dig]
Definition
test your name servers, replaced [nslookup] (dig does not append the search path)
Term
[nslookup]
Definition
test your name servers older less powerful command
Term
NFS: Network File System
Definition
used to Linux to Linux machines, allows you to mount a remote file system into any directory tree.
Term
/etc/exports
Definition
where you create permanent export directories used by NFS. export is like sharing on the network.
Term
mount
Definition
can mount from [fstab /home/marko] and mount it
Term
fuser
Definition
lets you find out which users have a file open
Term
CIFS
Definition
Common Internet File System
Lets NetBIOS run on top of TCPIP
Term
SMB
Definition
Server Message Block: protocol that lets Linux communicate with Windows; like mapping network drives [ NetBIOS //server/share]
Term
[testparm] (samba command)
Definition
does a syntax check on /etc/samba/smb.conf
Term
[nmblookup] (samba command)
Definition
displays registered names of a host
Term
[smbclient] (samba command)
Definition
lets you connect Linux client to the windows server
Term
[smbstatus] (samba command)
Definition
lists currently existing connections to the samba server
Term
CUPS
Definition
PORT 631
Print Server
http://localhost:631
Term
PPD
Definition
Postscript Printer Definition: postscript = open standard for printing files
Term
[lpadmin] (Printing Command)
Definition
create printers from the cmd prompt
Term
[lpoptions] (Printing Command)
Definition
to change properties of a printer
Term
[lpr] or [lp] (Printing Command)
Definition
to print something
Term
[lpq] or [lpstat] (Printing Command)
Definition
view the print queue
Term
[lprm] or [cancel] (Printing Command)
Definition
remove a job
Term
NIS: Network Information Services
Definition
do domain wide authentication Services, replicated critical files only works on Linux and Unix. Originally called "Yellow Pages"(YP)
Term
LDAP
Definition
Like NIS but works on all platforms. It is COMPATIBLE WITH WINDOWS ACTIVE DIRECTORY
Term
cn (LDAP record Type)
Definition
canonical name: user name printer file or directory. (lowest level name)
Term
ou (LDAP record Type)
Definition
organizational unit: group users together into an organization (engineering, IT, finance)
Term
dc (LDAP record Type)
Definition
domain component: where you specify your domain, all orgs belong to BYUI +++requires two components dc=byui, dc=edu+++
Term
MIME: Multipurpose Mail Extension
Definition
way we can determine the type of a file, what kind of data and what should we use to open it. (replacement for file types such as .txt .png .jpeg etc)
Term
SMTP: Simple Mail Transfer Protocol
Definition
Used to SEND mail ONLY not to recieve
Term
MTA (Email component)
Definition
Mail transfer agent: used to send the mail to its destination or destination server uses IMAP and POP.
Term
MDA (Email component)
Definition
Mail delivery agent: compare the mail to a number of rules, and decide what to do with it. so it Filters. Postfix and Sendmail.
Term
MUA (Email component)
Definition
Mail user agent: your mail client. Examples: Novell Evolution, KMail, Mozilla Thunderbird, Mutt(NO GUI), Pine (NO GUI), mail(NO GUI).
Term
POP and IMAP
Definition
MTA's (Mail Transfer Agents) that distribute mail to clients from server
Term
Postfix
Definition
MDA (mail delivery agent) newer, easier to config and manage. Is compatible with Sendmail
Term
Sendmail
Definition
Old MDA (Mail Delivery Agent) Old and reliable, but difficult to manage
Term
Procmail
Definition
setup file in /home/.procmailrc to configure sorting options
Term
inetd and xinetd
Definition
super daemon: listens on a port and starts a daemon when a request for it comes in. (xinetd is the improved version)
Term
TCP wrapper
Definition
adds security to other less secure daemons, telnet daemon is insecure, so instead of rewriting, use TCP wrapper which wraps itself around it adding more security, uses host.allow and host.deny statements
Term
[hosts.allow] and [hosts.deny]
Definition
statements used by the TCP wrapper similar to access control lists
Term
ssh (Secure Shell)
Definition
More secure version of Telnet with more features. You can copt files and use tunneling of other protocols within the SSH) [ssh -x] allows x server to run across the server
Term
DHCP (Dynamic Host Configuration Protocol)
Definition
assigns a client a network/host address. Uses /etc/dhcpcd.conf and etc/sysconfig/dhcpcp
Term
apache2
Definition
Web Server; home page is in /srv/www/htdocs. To START [rcapache2 start] and STOP [rcapache2 stop]
Term
resident set
Definition
which pages are currently in physical memory
Term
working set size
Definition
number of pages in current memory
Term
thrashing
Definition
when you spend all time moving pages between physical and virtual memory and don’t have any time to get real work done
Term
principle of locality
Definition
program and data references within a process tend to cluster. ( even though I have a process that is this long, how much do i really need right now)
Term
p bit (Paging)
Definition
physical bit: 0=(in physical memory) 1= (in virtual memory)
Term
m bit (Paging)
Definition
modified bit, to know if we need to write something before you reuse the frame. if both aren’t unmodified then replace the LRU file (least recently used) WHO THE L R U?
Term
critical section
Definition
section of the program that we need to protect with a semaphore,We used to lock at beginning and unlock at the end. Instead just isolate the critical code
Term
livelock
Definition
you have two processes concurrently and their contending with each other over some resource, ex: create a Boolean and set it true and other program sets it false, each changes truth value.
Term
race condition
Definition
if two processes are running at the same time running concurrently I get different results than if they were running separately
Term
semaphore
Definition
signaling technique that will lock resources to a process to prevent deadlock, or any problems. (sends our semwait and semsignal codes)
Term
Conditions for Deadlock to Occur
Definition
Mutual Exclusion, Hold-and-Wait, and No Preemption.
Term
mutual exclusion (deadlock causers)
Definition
only one process can do it at a time (printing, updating files)
Term
hold-and-wait (deadlock causers)
Definition
if a process gets a resource it can hold it until it gets the one it needs.
Term
no preemption (deadlock causers)
Definition
resource cannot be removed from a process
Term
Circular Wait
Definition
Means you have dealock
Term
The Whole Shebang (bash scripting)
Definition
#!/bin/bash
Term
parameters (bash scripting)
Definition
get stored in $and, $1, or $2 variables
Term
read (bash scripting)
Definition
[read -p $ans]
Term
UNTIL loop
Definition
Similar to WHILE LOOP but does the check at the end.
Term
-lt versus <
Definition
< is lexicographical; it compares the first character, 12<2 is TRUE (1<2(first letter))
-lt is numerical
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