Nick's technical musings
I recently discovered I had an open mail relay. This situation was particularly frustrating because tools like mxtoolbox kept reporting my mail server as not having an open relay. All the standard tools simply looked at failure to issue commands as evidence that relay access was denied, when in fact that was NOT the case! … Continue reading Find SMTP Open Relays with SWAKS → The post Find SMTP…
I recently needed to take a mysql database export from one docker container and import it into a different docker container. It took a while to get the commands I needed, with this stackoverflow thread helping me to understand what needed to be done. I initially tried to use docker exec -it <container> /bin/bash but … Continue reading Pipe mysql export from a docker container into a different…
I tried to spin up a vanilla mailcow-dockerized setup but couldn’t get it to come up. Logs said that the DNS checks for unbound were failing I tried all sorts of things to no avail. Querying the dns on my host as well as via bash in the container itself worked. What eventually fixed it … Continue reading Fix mailcow unbound DNS resolution failed healthcheck → The post Fix mailcow unbound DNS…
I kept having a frustrating issue where my 40gig link for all hosts in my 3-node mesh network would go down if one host became unresponsive. This would cause the healthy nodes to fence themselves and take the whole cluster down until I rebooted them. I needed a way to fall back to my 1gig … Continue reading Add backup link for Proxmox cluster → The post Add backup link for Proxmox cluster appeared…
I wanted an easy way to forward ports from my VPS to a host on my local network. Firewalld and iptables were giving me grief, so I settled on using ssh port forwarding instead. I came across this gist which was super helpful. Now instead of dealing with firewall and iptables, I simply have an … Continue reading Secure port forwarding with ssh & systemd → The post Secure port forwarding with ssh &…
I had an annoying “chicken and egg” problem with nginx proxy manager. It has hosts configurations that reference DNS names that are only reachable over VPN. It also hosts headscale, which is required for VPN to establish properly for said DNS entries. Brought up from scratch (say, after a reboot) NPM fails to launch because … Continue reading NPM reboot workaround script → The post NPM reboot…
I wanted a quick way in the command line to get the disk usage of a bunch of zip files I downloaded in the previous day. I also wanted them sorted by filename and to have quotes surround each filename. I learned from this stackexchange post that du -ch is the command I want to … Continue reading Get a summary of disk usage from select files with find, sed, du, and xargs → The post Get a summary of…
My manual wireguard site to site solution worked but had latency issues. I wanted a more streamlined way to get my site to site VPN working properly. I decided to finally try out tailscale but didn’t want to rely on their servers, so I spun up headscale and hosted the control server myself. My sites … Continue reading Site to Site VPN with Tailscale subnet router → The post Site to Site VPN with…
I needed to give my CGNAT-backed home internet a way to have a public IP address. My first solution was to use wireguard directly, and forward ports as needed. I came across this article that helped me do it. The key was to enable packed masquerading so the return path could be completed. Example wireguard … Continue reading Port Forward from Internet to Wireguard interface → The post Port Forward…
I had a frustrating issue where prometheus blackbox exporter wasn’t able to check one of my websites and I couldn’t figure out why. I finally found this site which explained you can append &debug=true to the end of your probe in a URL string talking directly to blackbox. For example: http://prometheus:9115/probe?module=http_2xx&target=http://customsite.com:8096/web/&debug=true That finally got me…