In week 2 of my #SysAdmin class, we're talking about storage models and disks: DAS, NAS, SAN, Cloud storage, disk interfaces, #RAID, LVM, #ZFS, physical disks, and partition types and tables.
The exercises include spinning up #AWS#EC2 instances and filling up disk space, using up all inodes, and moving an EBS volume across different instances and OS.
look at the MBR and boot loaders, manually (well, perhaps tediously) write a bios partition table using dd(1), printf(1), and hexdump(1) (because using fdisk(1) would be just too easy)
pretend to be a (very simple) filesystem (again using dd(1) and friends)
look at the UFS / FFS filesystems and the newfs(8) and dumpfs(8) tools
discuss file types and where they belong (hier(7))
It's week 4 for my #SysAdmin class. We're discussing types of software (firmware, OS, " add-on") and how difficult it is to draw those lines, review the basic steps of OS installation, and then move on to package managers and all the headaches those solve / bring with them.
And yes, we do talk "curl | sudo bash", supply-chain and left-pad.
This week in my #SysAdmin class, we continue with networking.
We start on our box and strace/ktrace a simple telnet command to see how we even get to the point of #DNS resolution (/etc/nsswitch.conf, /etc/hosts, /etc/resolv.conf), then #tcpdump a simple HTTP request to observe:
#ARP / #NDP calls to find the default route and local resolver
It's week 07 of my #SysAdmin class, high time we talk about the cause of (and solution to) all problems: the #DNS.
We look at the history of the DNS and how we used to copy giant hosts file around, trace DNS packets from resolvers to the root servers and the various authoritative NS using our good friend #tcpdump, talk about #TLDs, fetch the root zone from InterNIC to bootstrap our resolver, look at different RRs, reverse lookups, and touch upon #dnssec.
After this week's Spring Break, we return in my #SysAdmin class to dive into #SMTP.
We start with an overview of the ecosystem consisting of MUAs, MTAs, MDAs, Access Agents, and tcpdump a simple manual SMTP session over telnet. We then talk about STARTTLS, MTA-STS and #DANE, before diving into #spam defenses, including #SPF, #DKIM, and #DMARC, all with practical examples, tracking lookups and traffic on the sender and receiver.
We cover "scripting" vs. "programming" vs. software engineering, choosing the right tool for the job, extol the virtues of #perl's taint checking, lambast "clever" code, and frequently refer to F. Brooks and the Mythical Man-Month. (Yes, we could spend a whole semester on this topic, too.)
This week, our #SysAdmin syllabus covers backups and restores, including use of dump(8), #rsync, and flux-capacitors (e.g., ZFS snapshots, Apple TimeMachine, NetApp's WAFL). We also were supposed to talk about #syslog and monitoring, but honestly, chances are we'll spend most of our time on the #xz#backdoor.
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