Nmap stuck in ping scan phase #1922
Description
I use the latest Nmap version compiled from source with these scanning options:
ports=80,8080,8081,8090,8000,9080,81,443,8443,4343
"$main_folder/nmap/nmap" \
-PE -PS"$ports" -PP \
-sSV -p "$ports" \
-iL "$input_file" \
-v --open \
--script http-title,http-server-header,ssl-cert,http-headers \
-T5 --script-timeout 5m --host-timeout 5m \
-oA web_recon
(yes my ping options are particular)
From time to time Nmap tends to be stuck in the ping scan phase. It seems to be blocked indefinitely because I discover it in this situation after a few hours with no progress. I kill it and resume the scan. After the resume, the problem does not appear immediately so it is very hard to diagnose and thus I do not think it happens with particular hosts either...
As you can see I already use --host-timeout as a safety against such cases but this does not seem to apply here.
It is still responsive though when I press ENTER or increase/decrease verbosity/debug.
Here is what I get:
Initiating Ping Scan at 14:12
Scanning 4096 hosts [11 ports/host]
Ping Scan Timing: About 16.93% done; ETC: 14:15 (0:02:32 remaining)
Ping Scan Timing: About 30.54% done; ETC: 14:16 (0:02:53 remaining)
Increasing send delay for 10.180.43.38 from 0 to 5 due to 11 out of 12 dropped probes since last increase.
Ping Scan Timing: About 30.65% done; ETC: 14:18 (0:04:00 remaining)
Ping Scan Timing: About 30.74% done; ETC: 14:19 (0:05:06 remaining)
Ping Scan Timing: About 30.84% done; ETC: 14:21 (0:06:12 remaining)
Ping Scan Timing: About 30.93% done; ETC: 14:22 (0:07:18 remaining)
Ping Scan Timing: About 31.03% done; ETC: 14:24 (0:08:22 remaining)
Ping Scan Timing: About 31.12% done; ETC: 14:26 (0:09:27 remaining)
Ping Scan Timing: About 31.21% done; ETC: 14:27 (0:10:30 remaining)
Ping Scan Timing: About 65.81% done; ETC: 14:20 (0:02:44 remaining)
Ping Scan Timing: About 98.93% done; ETC: 14:58 (0:00:30 remaining)
Ping Scan Timing: About 98.93% done; ETC: 14:59 (0:00:30 remaining)
Ping Scan Timing: About 98.93% done; ETC: 14:59 (0:00:31 remaining)
Ping Scan Timing: About 98.93% done; ETC: 15:00 (0:00:31 remaining)
Ping Scan Timing: About 98.93% done; ETC: 15:01 (0:00:31 remaining)
Ping Scan Timing: About 98.93% done; ETC: 15:01 (0:00:32 remaining)
Ping Scan Timing: About 98.93% done; ETC: 15:02 (0:00:32 remaining)
Ping Scan Timing: About 98.93% done; ETC: 15:02 (0:00:32 remaining)
Ping Scan Timing: About 98.93% done; ETC: 15:03 (0:00:33 remaining)
Ping Scan Timing: About 98.93% done; ETC: 15:03 (0:00:33 remaining)
[...]
Ping Scan Timing: About 98.93% done; ETC: 18:30 (0:02:46 remaining)
Ping Scan Timing: About 98.93% done; ETC: 18:33 (0:02:48 remaining)
Ping Scan Timing: About 98.93% done; ETC: 18:36 (0:02:50 remaining)
Stats: 78:24:08 elapsed; 3346473 hosts completed (62423 up), 4096 undergoing Ping Scan
Ping Scan Timing: About 98.93% done; ETC: 18:37 (0:02:51 remaining)
Stats: 78:24:09 elapsed; 3346473 hosts completed (62423 up), 4096 undergoing Ping Scan
Ping Scan Timing: About 98.93% done; ETC: 18:37 (0:02:51 remaining)
Debugging Increased to 1.
Debugging Increased to 2.
Verbosity Increased to 2.
Stats: 78:35:04 elapsed; 3346473 hosts completed (62423 up), 4096 undergoing Ping Scan
Ping Scan Timing: About 98.93% done; ETC: 18:48 (0:02:58 remaining)
Current sending rates: 0.00 packets / s, 0.00 bytes / s.
**TIMING STATS** (282967.9062s): IP, probes active/freshportsleft/retry_stack/outstanding/retranwait/onbench, cwnd/ssthresh/delay, timeout/srtt/rttvar/
Groupstats (44/4096 incomplete): 1/*/*/*/*/* 1.00/2/* 300000/124671/153714
a.b.c.d: 0/11/0/0/0/0 10.00/75/0 300000/-1/-1
w.x.y.z: 0/11/0/0/0/0 10.00/75/0 300000/-1/-1
[44 lines in total with different IPs but same values]
Current sending rates: 0.00 packets / s, 0.00 bytes / s.
Overall sending rates: 1.64 packets / s, 64.48 bytes / s.
I am not aware of the internals of the scanning engine so I have troubles interpreting this output.
Do you have any suggestion for me? Could I be helpful in providing more information or performing some action to help in debugging this?