How to do same as 'nmap' command from within a D program?

[frame]

On Saturday, 22 January 2022 at 20:55:38 UTC, Daren Scot Wilson 
wrote:

> I don't see any D std.* libraries that do this. Are there a Dub 
> packages I should look at?

If you really want to this in D without any external app or OS 
API you could just ping all possible hosts, see which respond and 
then use `getHostByAddr()` to find the hostname.

Another more professional way is to query the ARP protocol, where 
you send a packet as broadcast to all interfaces in the network 
to find a MAC for a given IP - if any host responses with a MAC, 
the host is up.

You have to build the packet data for yourself, there are 
examples on the web. The socket to use is family:INET, type:RAW 
and protocol:ICMP for ping or RAW for ARP or anything that isn't 
listed in D.

As you can see, it's required to test every possible IP out 
(except for any other discovery protocols supported by your 
network/router). For this reason, any OS does this scan 
periodically and caches the result. On UNIX you can just directly 
read the file `/proc/net/arp`, no need to use nmap.