Merge branch 'master' of gitlab.com:shockrah/csnotes

312/hash.md

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+# Cryptographic Hash Functions
+
+## Random Jargon
+
+_If you made it this far you know what all of this is but we need these terms because "muh academic vernacular"_
+
+* Variable Length Input
+* Fixed size output
+
+```python
+a = {
+	'first',
+	'second',
+}
+```
+Both `first` & `second` as inputs result in distinct references of the same size.
+
+* One-way property
+
+You should **not** be able to use a hash result(i.e. reference) to find an input. 
+
+In English: _Only inputs can find outputs, not the other way around._
+
+* Two-way property/ Collision-free Property
+
+**2** identical data inputs will map to the same output
+
+## What does a hash provide?
+
+* Integrity checks
+
+* Message Digest / Authentication
+
+_Hashes are not secure ffs_. When we say authentication we really mean that we are checking to ensure there has been no changes to the original message.
+_NOTE:_ this really doesn't guarantee anything in communications susceptible to man-in-the-middle attacks.
+
+**Let's get real for minute:** Think of it this way a message is like a car and the key is our hash. If the key doesn't fit in the slot then its not our car, **but** if we sent our car + key oversees whoever steals the car + key has full control and we lose security effectively. Using SSL is _kinda_ like putting that car + key combo in a box that nobody except the recipient can open.
+

312/kerberos.md

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+# Kerberos
+
+Method of distributing keys where we deal with clusters made of two parts:
+
+* Authentication server
+* Ticket-granting server
+
+

312/key-dist.md

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+# Key Distribution
+
+A wants to talk to B but securely(duh).
+A trusted third party steps in to provide keys
+
+
+## Needham-Schoeder
+
+> _used to authenticate users_
+
+Say we have A & B that want to talk.
+
+```
+A sends (IDA, IDB) to KDC
+KDC sends Enc(SessionKeyA, IDB, Nonce1, Enc(SessionKeyB, SharedKeyA, IDA)) to A
+A sends Enc(SessionKeyB, SharedKeyB, IDA) // this bit came in the package from last round
+...
+...
+```
+
+## Denning
+
+Fixes step 3 with timestamps. We also shorten the overall process.
+Problem: both parties need to be time synchronized.
+
+NOTE: the Sessionkey below is shared between A and B. THe SharedKeyX is shared between the Key Distribution Center and the user.
+
+1. A sends {IDA, NonceA} B
+2. B sends {NonceB, Enc(SharedKeyB, [IDA, NonceA, TimeB])} to KDC 
+3. KDC sends {Enc(SharedKeyA, [IDB,, NonceA, SessionKey, TimeB), E(SharedKeyB, [IDA, SessionKey, TimeB]), NonceB} to A
+4. A sends {E(SharedKey, [IDA, SessionKey, TimeB]), E(SessionKey, NonceB} to B
+
+## Kerberos
+
+The model itself can be  thought of similar to 

312/wireless-sec.md

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+# Wireless Security
+
+Let's go over the biggest most issue with wireless networks/communications
+
+> Wireless signals must be broadcast
+
+This means if _anything_ wants to communicate wirelessly then, everything/everyone will be able to hear those messages.
+This also means that wireless receivers have to filter through a ton of noise/signals that aren't meant for it.
+
+Taking the more innocent approach for a minute: it's kinda like walking around a crowded place, while talking to someone, you _can_ hear other people but mentally you are discarding other conversations as you're paying attention to the person you are talking to.
+
+> DOS - Denial of Service
+
+Furthering the crowded room example if you and a friend were talking and someone else started screaming talking to them would become much harder/impossible at some point.
+

412/.gitignore

@@ -1,2 +1,4 @@
 *pdf
 homework/
+todo.md
+

412/data.md

@@ -35,6 +35,10 @@ Outsourcing the storage for users to services like Onedrive because it becomes t
 Ensure that the OS gets its own space/partition on a drive and give the user their own partition to ruin. That way the OS(windows) will just fill its partition into another dimension.
 
 
-# Print Services
+# Backup
+
+Other people's data is in your hands so make sure that you backup data in some way.
+Some external services can be nice if you find that you constantly need to get to your backups.
+Tape records are good for archival purposes; keep in mind that they are slow as hell.
 
 

412/mail.md

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+# Email Service
+
+> Standards 
+
+Try to keep things with standard protocols
+
+> Automation
+
+Have some system that can create emails for you instead of manually creating them
+
+> Redundancy
+
+Backup mail servers to insure against partial loss
+
+> POP/IMAP
+
+Most servers accept IMAP and not POP anymore
+
+> Encryption
+
+For the most part we use SSL on the mail server to retain privacy among the users.
+

412/midterm.md

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+# Midterm Sample Questions
+
+Difference between NAS and SAN?
+
+Subnet: 
+
+* What kind of class is the given IP?
+
+* What is the subnet mask, network address, etc?
+
+* Subnet addresses?
+
+`Host & subnet mask(classless)`
+
+BTW: this is the analog of the network address(classful addressing). When we talk about network addresses we are implying a classful network.
+
+* Subnet bits
+
+i.e. 21 => 8+8+5+0 <= `5` is the odd one out so we have _5 subnet bits_
+
+* VLSM - Variable Length Subnet Mask
+
+
+Suppose we want to assign addresses to the following networks with x many hosts.
+A:600; B:1000; C:200
+
+`150.180.0.0/16`
+`150.181.0.0/16`
+
+Start with the largest network B : requires 1000 hosts.
+
+Hosts part requires 10 bits so we have an IP/22.
+
+Network address then is (subnet address)150.180.0.0/22 - (broadcast address)150.180.3.255/22
+
+**NOTE:** I included both the subnet(network) address and the broadcast for sake of brevity.

412/monitoring.md

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+# Service Monitoring
+
+Several types of monitoring: 
+
+## Building Monitoring System
+
+If your monitoring a lot of _stuff_ know that you will could have lots of stuff going across the network(in some cases).
+Know that we have to _get data, store data, and ultimately view data_.
+
+## Historically
+
+SNMP: Usually you will get back a ton of data 

412/pass.md

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+# OpenFiler
+
+> both on the browser and the regular user account
+openfiler
+openfiler 

412/vlsm.md

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+# VLSM Examples
+
+Say we have the IPs: 210.19.[14 -> 19].0/24
+
+We want to create to networks which support this many hosts
+
+## Part A
+* A: 1000 hosts
+* B: 500 hosts
+
+Doing A first(because it's bigger):
+
+Third octet in our IP has the bit pattern of `0000 11100`
+
+If we want to support 1000 hosts we need to borrow the last two bits of that pattern: 
+
+> __problem__: one of those is 1 which means we can't borrow it as its part of our given network address.
+
+Thus this problem then can't be done given this information.
+
+If we had been given x.x..12.0 we could do it because 12's bit pattern is `0000 1100`, which leaves the last two bits as 0's that we can use for the hosts.
+
+## Part B
+
+This time we need to support 500 hosts so we need 9 bits for the hosts. This time we can use `x.x.14.0` as our network address
+
+Our mask is /23 `255.255.154.0`. This leaves our network address as `210.19.14.0`.
+
+* The first host is x.x.14.1
+
+* The last host is x.x.15.254
+
+* Broadcast is x.x.15.255

readme.md

@@ -1,9 +1,32 @@
-# CSUMB NOTES
+# Everyone else
+
+To some degree these notes are personal so there are a few mistakes that I just can't be bothered dealing with.
+Some mistakes however are just because I wrote those notes during class, likely rushed but meh just take it with a grain of salt sometimes.
+
+# Prelim to Students
+
+Some of these courses are very bs'd or missing information.
+This is (mostly) intentional: some courses cover lower division material that I couldn't be bothered to write down in this repository.
+
+Also I'm basing lower division material on the curriculum of [Irvine Valley College](http://ivc.edu/Pages/default.aspx).
+
+# Directory Guide
 
 ## 311/ - Introduction to Networking and internet Programming
 
+## 312/ - Network Security 
+
+## 334/ - Operating Systems
+
 ## 337/ - Introduction to Computer Architecture 
 
+## 338/ - Software Design
+
+**Oh boy**: I'm gonna level with you I took nearly no notes so instead I'm providing a decent source for learning design in software:
+
+
 ## 363/ - Introduction to Database systems
 
+## 370/ - Algorithms
 
+## 412/ - Network Administration