Networking
Ubuntu basics
To see network details:
ip a
Bring an interface up/down:
sudo ifconfig enp4s0 down sudo ifconfig enp4s0 up
DNSMasq
I disabled systemd and use dnsmasq for bitpost routing.
It provides static IPs to LAN via MAC addresses.
It performs DNS caching. Use /etc/resolv.conf to set up fallback DNS.
Update to new ISP
I did this for google fiber on 2022/09/30.
- Set up new ISP while keeping old
 - Update any ethernet cables and NIC cards; I need cat6 from google fiber router GRAY port (2Gbps); I ordered a 10G network card on Amazon, not here yet.
 - Remove old ISP cable from RJ45, plug in new ISP cable
 - ssh 192.168.22.1 to get a terminal to bitpost box
 - check that a new IP was obtained via `ip a`
 - RESTART THE FIREWALL, it MUST BE STARTED after the IP is obtained! This was the kicker that had me scratching my head for an hour.
 
sudo su - edit_firewall # Ctrl-D to save and exit and restart it
- Check that you can ping google.com; check that LAN is up and ready
 - Go update ALL domains.google.com DNS records with the new IP!
 - Pray for IP stability! reddit commentors gave me hope, we will see...
 
Force apt to use a proxy
Edit /etc/apt/apt.conf:
Acquire::http::Proxy "http://myproxy.com:####";