Creating a CSR with a SAN - openssl
Fixing ERR_CERT_COMMON_NAME_INVALID by generating an openssl CSR with Subject Alternative Names, using a reusable san.ini config file and openssl req.
VLAN Tagging Mac Thunderbolt NIC IP Traffic
Click-by-click steps for adding an 802.1Q VLAN tag to a Thunderbolt Ethernet adapter on macOS so you can plug a MacBook into a switch's trunk port for testing.
Create Windows KVM VM from Command Line
Create a Windows KVM virtual machine on Ubuntu 18.04 from the command line with qemu-kvm, libvirt, virt-install, and a netplan bridge. No OpenStack required.
Packet Tracing Reference
Quick reference for capturing and filtering network traffic on Ubuntu using tcpdump and tshark. Covers port filters, host filters, combined expressions, and tshark HTTP capture.
Ubuntu NFS Server Setup
Install and configure an NFS server on Ubuntu 18.04 with nfs-kernel-server, set up /etc/exports for a subnet, apply with exportfs, and mount from a client.
Transferring files to Windows through Python's SimpleHTTPServer
Push a one-off file to a locked-down Windows box from Linux by hosting it with `python -m SimpleHTTPServer` and grabbing it in Internet Explorer.
Free HTTPS Certs with LetsEncrypt's Certbot
Install LetsEncrypt's certbot on Ubuntu and issue a free HTTPS certificate using the standalone HTTP challenge, then convert the files for HAProxy use.
Ubuntu: Blindly Trusting the Corporate CA
Extract a corporate CA certificate with openssl s_client and install it on Ubuntu via /usr/local/share/ca-certificates and update-ca-certificates.
Fix shrunken USB drive after using as boot disk
Restoring a USB drive's full size on macOS after dd or Etcher shrank it for a boot disk, using diskutil eraseDisk and, if needed, zeroing the partition with dd.
Remote Access: Build a Dial-Home Device
Build a persistent reverse SSH tunnel from an Ubuntu box at a customer site to your own pivot VPS, so you can remote in without a VPN.
SPF for Trusted Emails
Configure a Sender Policy Framework DNS record so mail servers trust emails from your domain. Covers finding your external IP and setting the TXT record.
Creating a Wireless Router for Wired Servers With Ubuntu Server
Turn an Ubuntu Server into a WiFi-to-wired NAT gateway using netplan, IP forwarding, and iptables MASQUERADE so switched servers can reach the internet.
Connecting Ubuntu 18.04 to WPA WiFi from CLI
Connect Ubuntu Server 18.04 to a WPA2 WiFi network from the command line using wpa_supplicant, iwlist, and netplan, including offline package install steps.
Launching Chrome from a Remote Ubuntu Server over SSH
Run Chrome on a headless Ubuntu server and render it on a Mac with SSH X11 forwarding, XQuartz, and ssh_config tweaks. No VNC, RDP, or desktop install.
Scheduled Availability Email Alerts
Write a cron-driven bash script that pings a host every minute and sends a throttled email alert on failure, using the mail command and a token file.
Postfix Send-Only Mail Service
Install and configure Postfix on Ubuntu as a local send-only SMTP server for alert emails, including hostname setup, main.cf tuning, and the mailutils tools.
Transfer Domain from GoDaddy to Cloudflare
Transfer a domain from GoDaddy to Cloudflare for faster DNS propagation and cheaper registration. Covers unlocking, auth codes, and finalizing the move.