System Administration

Week 7, The Domain Name System, Part II

In this video, we dissect #DNS lookups performed on our EC2 instance, then discuss just how a caching resolver performs the lookup before we turn our instance into such a resolver.

https://youtu.be/z55ULZcKP8A

System Administration

Week 7, The Domain Name System, Part I

In this video, we are beginning our discussion of the #DNS, the Domain Name System. We go back to the early days of the internet when copying /etc/hosts from system to system was the way to resolve hosts, and we cover the structure of the domain name space and the creation of the top-level domains.

https://youtu.be/-bpIT7M9i00

System Administration

Week 6, Networking II: ICMP

In this video, we demonstrate the use of the Internet Control Message Protocol or ICMP (and its #IPV6 equivalent ICMP6) by tracing and analyzing ping(1) and traceroute(1) invocations.

https://youtu.be/JQn8PgfZ68M

System Administration

Week 6, Networking II: ARP and NDP

In this video, we illustrate the functionality of the Address Resolution Protocol (ARP) and it's #IPv6 equivalent, the Neighbor Discovery Protocol (NDP).

https://youtu.be/1gtkpbF_h6M

System Administration

Week 6, Networking II: A simple request II

In this video, we pick up our tcpdump output collected in the previous video and begin to analyze the packets we find in there. We observe our AWS instance being scanned by some random host on the internet, see the ARP requests and replies, our DNS query, and the TCP packets for our HTTP request, yielding an illustration how a simple request causes traffic across multiple layers.

https://youtu.be/UDXJSyyp_18

System Administration

Week 6, Networking II: A simple request

In this video, we trace a simple HTTP request made via telnet to find out just how exactly our application knows how to connect to the remote server. In the process we learn about the ktrace(1) utility (strace(1) on #Linux), as well as the nsswitch.conf(5), hosts(5), and resolve.conf(5) configuration files.

https://youtu.be/mw1YzFSYuwE

System Administration

Week 5, Networking I: A Network of Networks

In this video, we look at how independent networks connect to one another, how Autonomous Systems numbers allow us to identify network operators, and how peering between independent ASs works.

https://youtu.be/OOq7jGlhBjY

System Administration

Week 5, Networking I: The Physical Internet

In this video, we look at the physical structure of the internet, with a focus on submarine internet communications cables. Jumping from the bottom of the OSI stack all the way to Layer 9 ("political"), we then discuss how different countries use their political power to enforce internet blocks on their citizens, leading us to warrantless wiretapping in AT&T's room 641A.

https://youtu.be/4YrHdD1uIxs

System Administration

Week 5, Networking I: IP Allocation & IPv4 Exhaustion

Mommy, where do IP addresses come from? We discuss how IANA allocates IP addresses to the Regional Internet Registries and try to illustrate just how large the #IPv6 address space is.

https://youtu.be/r2GXh8uUgWc

System Administration

Week 5, Networking I: #IPv6 Basics

In this video, we get familiar with our Big Hero IPv6, looking at the structure of the IPv6 header and IPv6 address representations.

https://youtu.be/wZ5cmlIlP3I

System Administration

Week 5, Networking I: IPv4 Basics & CIDR subnetting

In this video, we cover the basics of the 32-bit IPv4 address and how we organize networks using Classless Inter-Domain Routing or CIDR subnetting. (Don't worry, #IPv6 comes in our next video.)

https://youtu.be/CxdN-TcpSk8

System Administration

Week 5, Networking I: Layers

In this video, we begin our longer discussion on the topic of "networking". We're using tcpdump(8) to capture a single TCP SYN packet and start looking at the MAC and IP information, teasing out each individual byte. And yes, we will mention those OSI layers...

https://youtu.be/qYWkJ2KyRHU

System Administration

Week 4, Multiuser Fundamentals

We don't have a video for this segment, but here are the slides discussing group dynamics, foundations of trust (and #ZeroTrust), like Least Privilege, headless users or service accounts, group permissions, many examples of different forms of multi-factor authentication #mfa, and raising privileges (a topic we'll come back to again later in the semester).

https://stevens.netmeister.org/615/slides/lecture04.pdf

System Administration

Week 4, Package Manager Pitfalls

In this video, we discuss some of the problems with package managers, native language-specific packaging solutions, and the implications of their use on dependency resolution, package integrity, and trust. We revisit the "left-pad" (2016) and "dependency confusion" (2021) incidents to illustrate some of these problems.

https://youtu.be/R3zlbOND00Q

System Administration

Week 4, Package Management

In this video, we continue our discussion of the difference between the operating system and so-called "add-on software". We conclude that in order to install and maintain all such software, we want to use a package manager, and illustrate common features by example of the 'dpkg', 'rpm', and #NetBSD's #pkgsrc tools.

https://youtu.be/dU66_sPjnXg

System Administration

Week 4, OS Installation

In this video, we run through the manual installation of #NetBSD onto a virtual machine to illustrate the details of the process from partitioning and mounting the disk, extracting the sets, installing the bootloader, creating device nodes to updating /etc/rc.conf.

We also discuss planning of the OS installation by looking at data classification into shareable/non-shareable and static/variable data.

https://youtu.be/XRTDMgIpK68