RustScan is considerably slower when using a "host" file rather than CIDR notation for essentially the same number of hosts

[t3chn0t3s]

Greetings,

I'd like to start by stating how amazed I've been with RustScan. It is jaw dropping fast! I recently installed it on Kali 2022.1 using the rustscan_2.0.1_amd64.deb file.

I found that if I scan using the '-a 172.25.170.0/24 -p22,80.443,445 -g' arguments it takes about 6 seconds to scan the 254 hosts.

I'm trying to comply to my scope as much as possible and know that 172.25.170.1 is out of scope. Since I am unaware of a way to instruct RustScan to only scan 172.25.170.2 - 172.25.170.254 I used the following nmap "command" to generate a host file, named scope.txt

nmap -sL -n 172.25.170.2-254 | awk '/Nmap scan report/{print $NF}' | tee scope.txt

I then used the '-a 'scope.txt' -p22,80,443,445 -g' arguments to scan. Unfortunately, this takes considerably longer to scan. For example, my most recent "test" scan took about 13 minutes to complete.

I did also try the '-a 172.25.170.2-254' argument but since I didn't see that format used in the documentation I canceled it about 5 minutes into the scan. I'm not sure that format was valid, but assuming that it was 5 minutes is still considerably longer than the 6 seconds it takes when using the CIDR notation (/24).

Finally, as a sanity check I did check the line count of my scope.txt file and confirmed its about 253 hosts/lines.

Thank you all for such a great tool. I look forward to using it regularly.