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Nmap with -sT parameter hangs on 7.94 #2672

randybock opened this issue Jun 23, 2023 · 3 comments

Nmap with -sT parameter hangs on 7.94 #2672

randybock opened this issue Jun 23, 2023 · 3 comments


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randybock commented Jun 23, 2023

Describe the bug
When running nmap with the -sT parameter, the scan never completes. Keeps just saying 0.00% done. Have let it run for more than an hour.

To Reproduce
Run nmap with -sT parameter. Runs fine when the parameter is removed

Expected behavior
I expect it to run within a few seconds. The same command worked perfectly in 7.93.

Version info (please complete the following information):

  • OS: Windows server 2012
  • Output of nmap --version:
  • Nmap version 7.94 ( )
    Platform: i686-pc-windows-windows
    Compiled with: nmap-liblua-5.4.4 openssl-3.0.8 nmap-libssh2-1.10.0 nmap-libz-1.2.13 nmap-libpcre-7.6 Npcap-1.75 nmap-libdnet-1.12 ipv6
    Compiled without:
    Available nsock engines: iocp poll select
  • Output of nmap --iflist
    Starting Nmap 7.94 ( ) at 2023-06-23 16:31 Central Daylight Time
    eth0 (eth0) fe80::5b7f:b21:7155:7e30/64 ethernet down 1500 3C:EC:EF:B2:54:42
    eth1 (eth1) fe80::7561:3224:ade4:5230/64 ethernet up 1500 AC:1F:6B:87:66:D3
    eth1 (eth1) ethernet up 1500 AC:1F:6B:87:66:D3
    lo0 (lo0) ::1/128 loopback up -1
    lo0 (lo0) loopback up -1

eth0 \Device\NPF_{6BCFDEC4-A31F-4CE4-82B1-56C4B1C2F3D5}
eth1 \Device\NPF_{E645965B-E8A9-46EF-BE19-82BAB3D8EBC7}
eth1 \Device\NPF_{E645965B-E8A9-46EF-BE19-82BAB3D8EBC7}
lo0 \Device\NPF_Loopback
lo0 \Device\NPF_Loopback

DST/MASK DEV METRIC GATEWAY eth1 261 eth1 281 eth1 281 eth1 281 lo0 331 lo0 331 lo0 331 eth1 281 lo0 331 eth1 261 eth1 281 lo0 331 eth1 281
fe80::5b7f:b21:7155:7e30/128 eth0 261
fe80::7561:3224:ade4:5230/128 eth1 281
::1/128 lo0 331
fe80::/64 eth0 261
fe80::/64 eth1 281
ff00::/8 eth0 261
ff00::/8 eth1 281
ff00::/8 lo0 331
Additional context

@randybock randybock added the Nmap label Jun 23, 2023
@randybock randybock changed the title Nmap with -sT parameter hangs Nmap with -sT parameter hangs on 9.94 Jun 23, 2023

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dksslq commented Jun 26, 2023

Default parallelism is 0, using --max-parallelism or nmap -sT xx hangs. its a bug specific to nmap windows-edition. check:

maxSocketsAllowed = MIN(maxSocketsAllowed, FD_SETSIZE - 1);

@randybock randybock changed the title Nmap with -sT parameter hangs on 9.94 Nmap with -sT parameter hangs on 7.94 Aug 2, 2023
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Thanks for reporting this. This is a known issue with Nmap 7.94 on Windows which has been fixed in preparation for the next release. The fix is in commit 0890822

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