Fall2020-CEG3120-ExamReview

Exam review for CEG3120 for Fall 2020

Recommendation: since filling out every topic would get ugly, I recommend creating a separate page for each topic.

Midterm Review Outline for Fall 2020

Git / GitHub

add
commit
push
pull
clone vs fork
branch

Features

checkout
merge conflicts
stashing
clean vs reset
GitHub issues
GitHub pull requests

Linux

file & directory permissions
ownership & groups
PATH manipulation
File System - what to expect in root folders
- /etc/
- /var/
- /proc/
- /dev/
- /bin/ & /sbin/
- /boot/
- /home/
User / group management
- Configuration files to note:
  - /etc/passwd , /etc/group, /etc/shadow
Service management
- systemctl
System logs
- Log files can cause disk bloat
- journalctl
  - Find user associated logs
  - Find service related logs

IT Knowledge

Partition tables, partitions, filesystems
Mounting partition(s)
- Role of /etc/fstab
RAID 0, 1, 5, 6
- Given situation, which RAID would you recommend?
cronjobs
- Where to add a cronjob - crontab
- Format of a cronjob

Networking

dotted quad (format of IPv4 address)
host
subnet
- Network prefix
- Subnet mask
- CIDR notation (substitute for long form subnet mask)
gateway
routing
- Read a routing table for where traffic will be routed
MAC addresses
- arp table associates MAC with IP
Hardware interface names (common)
- eth0, wifi0 / wlan0, lo
DNS
- Local hostname resolution
  - Role of /etc/hosts
  - Role of /etc/resov.conf
Ports (common)
- 22 (SSH), 80 (HTTP), 443 (HTTPS)
- Read output of netstat with flags (-n -t -l)
What an IP address tells you about the network:
- Private network prefixes:
  - 10.0.0.0/8
  - 192.168.0.0/16
  - 172.16.0.0/12
- Local network prefixes:
  - 127.0.0.0/8
Router (as separate hardware):
- NAT
- DHCP
Firewall
- INPUT, OUTPUT, FORWARD chains
- Can be managed at router level or host level
- Host level management in Linux: iptables
- Packet is blocked by first rule that matches in chain
Forward proxy vs VPN
Reverse proxies:
- Caching
- Load balancing (web servers)
  - Monitor services?
  - Allocation strategies
  - Connection maintainence
  - Session persistence

System level process control

Background processes
- move to background
- bring to foreground
User generated process independent of terminal connection
- nohup
- screen

Bash

IO redirection
Different types of quotes
~/.bashrc vs ~/.profile
source vs ./ vs running script using name
Variables and accessing variable values
Use arguments
- In a script
- In a script function
Conditionals (using the test command)
if statements
functions

SSH

keys (private vs public)

Final Overview for Fall 2020

Bigger Topics

User management
- directory vs database
- PAM
  - needs to know authentication methods
- SSSD
  - needs to know about auth servers, like LDAP
Load Balancing Proxy
- Layer 4 vs Layer 7
Web Servers
- default location of website
- Apache2 vs NGINX

Git

add
commit
push
pull
clone vs fork
init
branch
merge
checkout
hooks
- does a given hook belong server side or client side
- recommend a hook that goes with an action

System Files

/etc/hosts: Configure alias names for host ip-to-DNS
/etc/hostname: Personal machine's renaming

SSH

authorized_keys: A home for public keys
config: A file to resolve IdentityFiles to Hosts
role of private vs public key

Networking

private vs public IPs
CIDR notation
ports
traffic rules (security / firewall)

AWS

VPC
Security Groups
Instances (AMIs)
Regions (resource limitations)
Elastic IPs
cloud formations

Bash

wget
sftp
IO redirection
Different types of quotes
source vs ./ vs running script using name
Variables and accessing variable values
Use arguments
- In a script
- In a script function
Conditionals (using the test command)
if statements
loops
functions