How can I check which services are listening on all IPv4 interfaces (excluding localhost)?

Another quick command to try is `netstat -ntlpu4`. Just keep in mind, you’ll need to run it as root to get comprehensive results.

Remember, these commands can vary by operating system. For example, in a Linux environment you could use: `ss -4nl ! src 127.0.0.1`. This isn't just a bash-specific command; it can be run in different program environments too. Always check the relevant manual for your system.

About your method: it seems a bit off because you’re losing track of whether the services are TCP or UDP, which could confuse things. If you're looking only for IPv4, just use the `-4` flag with `ss` to simplify your command.

So instead of filtering afterwards, you can do: `ss -4tuln '! src 127.0.0.0/8'`. This avoids needing `grep` and `awk` for such a straightforward task! You can get everything you're looking for more efficiently with this approach.

Both `netstat` and `ss` have `-4` and `-6` flags to filter for IPv4 and IPv6 options. On Debian 12, you should find `ss` readily available. However, if you're working with legacy systems, `netstat` might be the better option overall. If you're only after IPv4 sockets, using `-tuln4` will be a good start.

You could also capture a broader view using auditd logs for the syscall log to bind. This method records all relevant actions across the system instead of just a snapshot in time.