Nmap Development mailing list archives

so is nmap connect scan broken?


From: "Mike ." <dmciscobgp () hotmail com>
Date: Mon, 9 Feb 2015 06:56:33 +0000

ok. so i have done more than a few tests here to confirm this. first off, this is windows i am on and i am scanning my 
local router. notice i said ROUTER and not localhost so i dont get flamed here. i know the limitations on that for 
windows. i just started noticing this because i normally dont do -sT scans. this post must go with that "operation in 
progress" output because i feel they go together with this issue. so here is my confirmation on it being broken. as i 
scan my router, lets just use a port not open, i get this with a SYN  coming back as a response 


4) 192.168.0.16.46975 > 192.168.0.1.1: S, cksum 0x6272 (correct), 3992783572:3992783572(0) win 1024 <mss 1460>IP (tos 
0x0, ttl  64, id 28202, offset 0, flags [none], proto: TCP (6), length:40) 192.168.0.1.1 > 192.168.0.16.46975: R, cksum 
0x7e1b (correct), 0:0(0) ack 3992783573 win 0  (notice the reset back)

connect() output :
i get this in nmap           1/tcp filtered tcpmux  no-response but notice that packet sniffer output here : 
) 192.168.0.16.40137 > 192.168.0.1.1: S, cksum 0xa50e (correct), 1644903897:1644903897(0) win 8192 <mss 
1460,nop,nop,sackOK>IP (tos 0x0, ttl  64, id 28210, offset 0, flags [none], proto: TCP (6), length:40) 192.168.0.1.1 > 
192.168.0.16.40137: R, cksum 0xf1be (correct), 0:0(0) ack 1win 0
so nmap does not see that reply? anyone feel free to chime in here
m|ke
(btw, this is NOT just on local subnet scanning, this happens even when i fired off packets to google.com. not only 
that, but as the scan finishes, it hangs for about 30 sec-min til close. only on connect it does that)                  
                      
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