Shell: ping, nslookup, port, traceroute, ifconfig and arp (#90)

Network troubleshooting from the device itself, in the Shell and over both
consoles. ping, nslookup, port and traceroute each run on a task of their
own and print as they go, to the console that asked; one at a time, and
`cancel` stops it. ifconfig and arp answer at once: the interfaces (Wi-Fi
and the VPN), which is the default route, the DNS servers, the neighbours.

nslookup asks a DNS server itself, so it can say which server answered and
in how long, and ask another. A sized ping finds what a tunnel really
carries.

With a how-to, "When the network doesn't work", and the rest of the docs.
tls, ntp and netstat from the issue's list are not in this.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EhqxQ49eCju4CzKYNjZzwT

site/content/howto/_index.md

@@ -1,6 +1,6 @@
 +++
 title = "How-tos"
-description = "Short recipes for things you will want to do: move files with your phone, set up the VPN, take a screenshot, record a track, capture radio packets, and what to try when something does not work."
+description = "Short recipes for things you will want to do: move files with your phone, set up the VPN, take a screenshot, find out why the network doesn't work, record a track, capture radio packets, and what to try when something does not work."
 template = "guide-index.html"
 page_template = "guide-page.html"
 sort_by = "weight"