Nmap Development mailing list archives

nmap supports TCP Fast Open?


From: Stephen Fung <mke2fs () gmail com>
Date: Wed, 21 Jun 2017 11:34:50 +0000

Hi,

Does nmap support TCP Fast Open or understand the corresponding TCP option?



nmap

====

# nmap -sS -Pn -p 80 aa.bb.212.39 -ddddd

[....]

SENT (3.2777s) TCP [xx.yy.190.22:57408 > aa.bb.212.39:80 S seq=2165075824
ack=0 off=6 res=0 win=1024 csum=0x2275 urp=0 <mss 1460>] IP [ver=4 ihl=5
tos=0x00 iplen=44 id=10606 foff=0 ttl=38 proto=6 csum=0xcaba]

**TIMING STATS** (3.2780s): IP, probes
active/freshportsleft/retry_stack/outstanding/retranwait/onbench,
cwnd/ssthresh/delay, timeout/srtt/rttvar/

   Groupstats (1/1 incomplete): 1/*/*/*/*/* 10.00/75/* 1000000/-1/-1

   aa.bb.212.39: 1/0/0/2/0/0 10.00/75/0 1000000/-1/-1

Current sending rates: 1.98 packets / s, 87.23 bytes / s.

Overall sending rates: 1.98 packets / s, 87.23 bytes / s.

Rejecting TCP packet because of bad TCP header

[....]



TCPDUMP

=======

    xx.yy.190.22.57408 > aa.bb.212.39.80: Flags [S], cksum 0x2275
(correct), seq 2165075824, win 1024, options [mss 1460], length 0

19:19:11.324337 IP (tos 0x0, ttl 118, id 27060, offset 0, flags [DF], proto
TCP (6), length 52)

aa.bb.212.39.80 > xx.yy.190.22.57408: Flags [S.], cksum 0xc0ee (correct),
seq 1645991327, ack 2165075825, win 8192, options [mss 1460,unknown-34
0x01000a05c0a4], length 0





Regards,

Stephen
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