Linux Operating System Flashcards
What is the first process started by Kernal called?
init
What are processes launched by init called?
child processes
where is the init process typically stored?
/sbin/init
PID
process ID - lots of processes rely on PID
PPID
Parent process id
what is generally used to search for processes?
top and ps
free command
frees memory from processes
ps -u user –forest does what
shows a tree of processes by the user user
ps aux is?
good and adds a user and just makes it look nice? idk 5 this
/lib
dynamic libraries and also supports static files needed for the boot process.
/usr/lib
also dynamic libraries and support static files for the /usr/bin and /usr/sbin
/var/log
logging!
/etc
usually contain teh configuration files for all the programs that run on linux/unix
Where are deamons’ config files stored
in a subdir of /etc
7 layers of internet communcation?
7Application 6Presentation 5Session 4Transport 3Network 2Data link 1Physical
1Physical
literally transmits electrical signals between the hosts. It’s the network card connected to a wire
2Data Link
defines rules for accessing physical layer. Specifies how to verify data recieved from the physical layer.
3Network
Enables routing of data, spefices how to recognize addresses and the next network point to send a node.
Internet and ICMP operate on this level
4Transport
sending host’s 4 recieves data and divides it into packets. The receiving provides error checking and unpacks packets and assembles the data.
5Session
Responsible for establishing and maintaining a connection between two machienes
6Presentation
Ensures information passingthroughout all layers is formatted corretly for 7
7Application
provides applications for a way to access networiking
TCP
a protocal that ensures data exchanged between two network hosts is exchanged reliably
what two protocals are used with IP
TCP and UDP
ICMP stands for?
Internet Control Message Protocol.
ICMP is used for what?
Testing connections between hosts
what layers are ports accessed at
The 4Transport layer
20 21
FTP
23
Telnet
25
SMTP
80
HTTP
443
HTTPS
110
POP3
137 138 139
NetBIOS
Well-know ports
0-1023
For well established services
Registered ports
1024-49151
Special Implementation
Orgs can apply for a reg port number to be assigned to their service
Dynamic Ports
49152-65535
Available for any use by any network service
usually used for temporarilly establish connections between two applications.
what layer does the MAC address oprate
2Data Link.
MAC address is hardcoded on the network board and cannot be changed.
If the last octet in an IP address is 0, what does that mean?
it is the network address. Eg 161.161.161.0. A host cannot use that IP address
what is the last octet of 255 reserved for
broadcast addresses.
Class A private IP range?
10.0.0.0 - 10.255.255.255
Class B private IP range?
172.16.0.0 - 172.31.255.255
Class C private IP range?
192.168.0.0 - 192.168.255.255
what are the two parts of an ipv4 addr?
Network and node(host)
network is first 3, node is final one
