Ping, traceroute and DNS

Three network checks, built in. They run on the machine that runs Home Screen, so they tell you what that machine sees: useful on a home server, a NAS or a Raspberry Pi, and for checking a service from the place it actually runs.

Nothing runs while you type. Type the command, and press Enter (or the button) in the panel that opens.

Ping

ping example.com or ping 192.168.1.1 sends four ICMP echo requests and shows each reply time, the packet loss, and the minimum, average and maximum.

• Ping and traceroute use IPv4. A name that has only IPv6 addresses is reported as such.
• Times on Windows are whole milliseconds (that is what the system reports); Linux and macOS show fractions.
• If the system does not allow programs to send ICMP without special rights (a restricted container, for example), the panel says so and shows TCP connect time to port 443 or 80 instead. That measures a handshake, not ICMP, and the result is labelled that way.

Traceroute

trace example.com (or traceroute, tracert) sends probes with a rising time-to-live and lists each router on the way with three timings, up to 20 hops. * means a probe got no answer, which is normal for routers that do not reply. It stops when the host answers, and gives up after about a minute.

If no router answers at all, the panel says so and suggests why (a firewall, or a system that does not pass these replies to programs without special rights) instead of showing a table of stars.

DNS records

dns example.com looks up the A records. Add a type, and optionally the resolver to ask:

Type	Example
dns example.com MX	Mail servers (shortcut: mx example.com)
dns example.com TXT	Text records such as SPF (txt example.com, txt _dmarc.example.com)
dns example.com AAAA, NS, CNAME, SOA, SRV, CAA	The other common types (aaaa, ns, cname, soa, srv, caa work as shortcuts too)
dns 8.8.8.8 or ptr 8.8.8.8	A reverse lookup: the name for an IP address
dns example.com MX @1.1.1.1	Ask a particular resolver instead of this machine’s

The panel shows the status (NOERROR, NXDOMAIN and so on), each record with its TTL, the resolver that answered, and a button for every record type, so you can step through them without retyping. Each row has a Copy button, and Copy result copies the lot as text.

The question goes to the resolvers this machine is set to use (read from Windows’ network settings, or /etc/resolv.conf). If none can be found it asks 1.1.1.1, and says so. Names are looked up exactly as typed: write international names in their xn-- form.

Also widgets

Ping, Traceroute and DNS records are in the widget gallery under Web & network.

Good to know

• These tools only work when the page is opened via localhost, 127.0.0.1 or a name listed in --allowed-hosts, like the curl runner. See Options.
• At most two checks run at once, and each is limited in count, hops and time. Host names are checked before use, and nothing is started as a separate program.
• Docker: ICMP from a container running as a normal user needs Linux’s net.ipv4.ping_group_range to include the container’s group. Current Docker versions set it; where it is not, ping falls back to TCP connect time and traceroute explains that it cannot read the replies. See Docker.
• Because these probe from the machine running Home Screen, anyone who can use the page can ask it to probe hosts the machine can reach. Keep the page private (see Privacy and security).