Show HN: netq – A script to fetch common network parameters, written in POSIX sh

A handy POSIX-compliant utility script to quickly fetch common network parameters. The script is written with portablity among GNU/Linux distros in mind. Hence, subcommands have numerous fallback tools and remote APIs to rely on for their function.

netq is not designed to be an alternative to ip and the like. It should be thought of as a helper script to be used in other scripts and tools in accordance with the Unix philosophy.

The output is produced on a best-effort basis, and may differ a bit dependeny on the availabilty of dependencies on host OS or the capabilities of remote APIs.

• Query local (private) IP and an indentifier name for the corresponding network (SSID, iface_name, etc)
• Query public IP, with support of many HTTP-based or DNS-based ip-finder methods
• Watch bandwidth usage of an interface
• Supports IPv4 and IPv6

The script is expected to just work on typical GNU/Linux systems, without needing to install non-default tools.

The following lists netq dependencies and the [command] they are used in. Not all of these tools are required. The | between entries means existence of one tool is enough. Not all public IP finders need every [public] tool. Refer to the table above.

• ip | ifconfig | nmcli | hostname : for getting local ip [local, list]
• curl | wget : for getting content from remote API [public, check]
• jq : for processing json [public]
• dig | host | nslookup : for DNS requests [public]
• ping : for pinging remote IP [check]
• awk bc date grep tr uname
• netsh netstat : only required in Windows/MSYS2 [local, list, bandwidth]

Check netq -h:

• netq local : Print local IP and connection name. Suitable for figuring out what the local IP of this machine is, so other devices on local network could access http servers running on this machine

• netq public : Print public IP address of the machine, as seen by remote machines on the internet. Also prints the two-character country code if the finder method supports it

• netq p -l : (used alias p for public) List public IP finder methods

• netq p -e 'dns-*' : Exclude all dns-based IP finder methods and print the public IP. Note that regualr expression dialect should be in POSIX Basic Regular Expression (BRE)

• netq p -e 'dns-*\|bare-*' -l : Exclude all methods that don't support extraction of country, and list the resulting finder methods (note the escape char before |). The -l here is useful for forming up -e

• netq -v p "dns-google,cloudflare.com" : Only use the passed finder methods in the specified priority (note CSV format). The -e switch in this case would act on the passed finders. The global -v switch enables debug logs

• netq p -r "ip-api.com" : Print the raw response of the remote API without any postprocessing. Useful for manually extracting parameters other than IP or country. Output varies depending on finder services

• netq -6 p : Print public IPv6 of the machine

• netq ls : List available interfaces

• netq bw wlp3s0 : Watch bandwidth usage for the passed wireless device. Output is updated on a single line, and Rx/Tx units would scale automatically

• netq check : Check internet connectivity by downloading a default website (https://www.google.com). This is useful to detect whether the machine is behind captive portals or not. Could be used as a pre-condition in systemd services that depend on internet connectivity

• netq c "https://example.com" : Same as above, but download the passed URL instead

• netq c -p : Continuously ping a default IP (8.8.8.8) and halt if ping is successful

For public IP finding, naturally, DNS-based methods (UDP) are faster than HTTP-based ones. What follows is a rough benchmark of supported public IP finders (note that different finders use different post-processing tools hence -r is used in this benchmark. Anyway, I believe network latency is the main bottleneck here):

• bandwidth-monitor : useful for checking desktop traffic usage, e.g. ensuring whether uploading of a file to a web service is progressing

• linter: shellcheck
• formatter: shfmt -i 4 -bn -ci -sr