Comments on: How to Code a Tcp Syn Port Scanner in C with Linux Sockets

By: jose alejandro varon carreño

jose alejandro varon carreño — Wed, 04 Jan 2023 00:51:19 +0000

¿tienen esta version pero con winsock ?

By: peacesheep

peacesheep — Sun, 22 May 2022 07:37:07 +0000

Error creating socket. Error number : 93 . Error message : Protocol not supported

By: Tuan Le

Tuan Le — Mon, 28 Mar 2022 16:28:42 +0000

Thank you for posting this!
I have a problem when I send an incorrect SYN-ACK packet to receive a RST packet. But I don’t receive RST packet, I checked on wireshark. What’s happened to me.
Can you help me! Thank you!

By: 4anonz

4anonz — Wed, 14 Jul 2021 21:10:50 +0000

In reply to Steve. Please I want to know why we divide the tcphdr->doff by 4. tcph->doff = sizeof(struct tcphdr) / 4 I have read once that we should provide the exact length of the TCP header

By: Hermann Stamm-Wilbrandt

Hermann Stamm-Wilbrandt — Sat, 25 Aug 2018 09:55:17 +0000

Thank you for posting this!
10 years after you posted this I really needed to send a single SYN packet against a port for taking over video stream of a FPV drone camera. My 1st E52 drone firmware did not respond to SYN packet at all. Until yesterday I worked around the connect() hang on that port by forking each such stealth port connect. The 2nd E52 drone I got had a different firmware, wich responded with [RST, ACK] to [SYN]. There seems to be a problem with connect() since I was not able to make it send a single SYN as needed to get drone video. Instead alwazs two SYNs were sent. This is where your “send single SYN” od your code really was needed. I added it as 1st step to pull_video.c for 1st firmware drone and was able to get rid of the fork()s that way. Now pull_video.c does capture drone camera .h264 streak thingle threaded!
https://github.com/Hermann-SW/wireless-control-Eachine-E52-drone/commit/ab10d132d56a3558bc7ad776826c922cba93db2a

Next step is to use syn(target,port) to unlock 2nd E52 firmware video capturing as well, that where ports responded with [RST, ACK]. Thanks again,

Hermann.

By: Amir

Amir — Fri, 22 Dec 2017 15:04:30 +0000

Hi
I’m really thankful ….
Could you send me a complete code for Fin scan ack scan syn scan connect scan
Thank you very much.

By: srj

srj — Fri, 20 Oct 2017 02:37:36 +0000

Haven’t run the program, but it doesn’t seem to stop !!
lines 232 – 235 are never reached! :/

By: Steve

Steve — Mon, 23 Jan 2017 23:43:22 +0000

In reply to bob. Those are warnings, not errors. If you copy and pasted correctly, everything should work fine.

By: bob

bob — Fri, 16 Dec 2016 22:39:20 +0000

im getting this error when compiling:

PortScanner.c: In function ‘receive_ack’:
PortScanner.c:189:5: warning: implicit declaration of function ‘start_sniffer’ [-Wimplicit-function-declaration]
start_sniffer();
^~~~~~~~~~~~~
PortScanner.c: In function ‘start_sniffer’:
PortScanner.c:232:5: warning: implicit declaration of function ‘close’ [-Wimplicit-function-declaration]
close(sock_raw);
^~~~~

By: Mizmor

Mizmor — Tue, 03 Dec 2013 15:27:00 +0000

Thank you so much! This is the best tutorial out there!

By: Simba

Simba — Tue, 01 Oct 2013 13:01:00 +0000

does (struct ip) == (struct iphdr) ? and exit(0) -> exit(1)?
in function start_sniffer(), when we break from while(1), shall we free(buffer)?

By: Mohammad Yasin

Mohammad Yasin — Fri, 21 Dec 2012 21:54:05 +0000

Hi …
I’m really thankful ….
I have to give a “humble” lecture about Port Scanning , it’s an activity in “Network Programming” in C and java …
this blog is very useful, and very close to our study in this field …
wish I can help you one day … :)

By: Binary Tides

Binary Tides — Fri, 09 Dec 2011 14:59:09 +0000

In reply to ??. linux code has been posted

By: ??

?? — Fri, 19 Dec 2008 03:03:00 +0000

I ‘m really admire your simple and logic roadmap about “Tcp Syn Portscan “.
I desire of the project sourcecode,because a simple test.
Could you send me (jinxinliu@gmail.com).I’m very appreciate for that,It will be a great thanks.Thank you.