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Test open port #38

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opened 2024-11-04 16:05:57 +01:00 by Benjamin_Loison · 7 comments
Benjamin_Loison commented 2024-11-04 16:05:57 +01:00
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Tracked at Benjamin_Loison/nmap/issues/3.

Tracked at [Benjamin_Loison/nmap/issues/3](https://codeberg.org/Benjamin_Loison/nmap/issues/3).
Benjamin_Loison commented 2024-11-04 16:10:50 +01:00
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Maybe already have opened an issue about it.

netcat -h
Output: 
OpenBSD netcat (Debian patchlevel 1.219-1)
usage: nc [-46CDdFhklNnrStUuvZz] [-I length] [-i interval] [-M ttl]
	  [-m minttl] [-O length] [-P proxy_username] [-p source_port]
	  [-q seconds] [-s sourceaddr] [-T keyword] [-V rtable] [-W recvlimit]
	  [-w timeout] [-X proxy_protocol] [-x proxy_address[:port]]
	  [destination] [port]
	Command Summary:
		-4		Use IPv4
		-6		Use IPv6
		-b		Allow broadcast
		-C		Send CRLF as line-ending
		-D		Enable the debug socket option
		-d		Detach from stdin
		-F		Pass socket fd
		-h		This help text
		-I length	TCP receive buffer length
		-i interval	Delay interval for lines sent, ports scanned
		-k		Keep inbound sockets open for multiple connects
		-l		Listen mode, for inbound connects
		-M ttl		Outgoing TTL / Hop Limit
		-m minttl	Minimum incoming TTL / Hop Limit
		-N		Shutdown the network socket after EOF on stdin
		-n		Suppress name/port resolutions
		-O length	TCP send buffer length
		-P proxyuser	Username for proxy authentication
		-p port		Specify local port for remote connects
		-q secs		quit after EOF on stdin and delay of secs
		-r		Randomize remote ports
		-S		Enable the TCP MD5 signature option
		-s sourceaddr	Local source address
		-T keyword	TOS value
		-t		Answer TELNET negotiation
		-U		Use UNIX domain socket
		-u		UDP mode
		-V rtable	Specify alternate routing table
		-v		Verbose
		-W recvlimit	Terminate after receiving a number of packets
		-w timeout	Timeout for connects and final net reads
		-X proto	Proxy protocol: "4", "5" (SOCKS) or "connect"
		-x addr[:port]	Specify proxy address and port
		-Z		DCCP mode
		-z		Zero-I/O mode [used for scanning]
	Port numbers can be individual or ranges: lo-hi [inclusive]

Note:

		-l		Listen mode, for inbound connects
Maybe already have opened an issue about it. ```bash netcat -h ``` <details> <summary>Output:</summary> ``` OpenBSD netcat (Debian patchlevel 1.219-1) usage: nc [-46CDdFhklNnrStUuvZz] [-I length] [-i interval] [-M ttl] [-m minttl] [-O length] [-P proxy_username] [-p source_port] [-q seconds] [-s sourceaddr] [-T keyword] [-V rtable] [-W recvlimit] [-w timeout] [-X proxy_protocol] [-x proxy_address[:port]] [destination] [port] Command Summary: -4 Use IPv4 -6 Use IPv6 -b Allow broadcast -C Send CRLF as line-ending -D Enable the debug socket option -d Detach from stdin -F Pass socket fd -h This help text -I length TCP receive buffer length -i interval Delay interval for lines sent, ports scanned -k Keep inbound sockets open for multiple connects -l Listen mode, for inbound connects -M ttl Outgoing TTL / Hop Limit -m minttl Minimum incoming TTL / Hop Limit -N Shutdown the network socket after EOF on stdin -n Suppress name/port resolutions -O length TCP send buffer length -P proxyuser Username for proxy authentication -p port Specify local port for remote connects -q secs quit after EOF on stdin and delay of secs -r Randomize remote ports -S Enable the TCP MD5 signature option -s sourceaddr Local source address -T keyword TOS value -t Answer TELNET negotiation -U Use UNIX domain socket -u UDP mode -V rtable Specify alternate routing table -v Verbose -W recvlimit Terminate after receiving a number of packets -w timeout Timeout for connects and final net reads -X proto Proxy protocol: "4", "5" (SOCKS) or "connect" -x addr[:port] Specify proxy address and port -Z DCCP mode -z Zero-I/O mode [used for scanning] Port numbers can be individual or ranges: lo-hi [inclusive] ``` </details> Note: ``` -l Listen mode, for inbound connects ```
Benjamin_Loison commented 2024-11-04 16:11:49 +01:00
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netcat -l

netcat: missing port number

netcat -l -p 33927

test

Port being chosen randomly.

telnet lemnoslife.com 33927
Output: 
Trying 54.37.228.22...
Connected to lemnoslife.com.
Escape character is '^]'.
test
```bash netcat -l ``` ``` netcat: missing port number ``` ```bash netcat -l -p 33927 ``` ``` test ``` Port being chosen randomly. ```bash telnet lemnoslife.com 33927 ``` <details> <summary>Output:</summary> ``` Trying 54.37.228.22... Connected to lemnoslife.com. Escape character is '^]'. test ``` </details>
Benjamin_Loison commented 2024-11-04 16:14:20 +01:00
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Related to Improve_websites_thanks_to_open_source/issues/494#issuecomment-2425677.

Related to [Improve_websites_thanks_to_open_source/issues/494#issuecomment-2425677](https://codeberg.org/Benjamin_Loison/Improve_websites_thanks_to_open_source/issues/494#issuecomment-2425677).
Benjamin_Loison commented 2025-03-07 17:52:08 +01:00
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How to test such a port without interaction?

How to test such a port without interaction?
Benjamin_Loison commented 2025-03-07 17:52:46 +01:00
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DuckDuckGo search Linux try to reach a port.

DuckDuckGo search *Linux try to reach a port*.
Benjamin_Loison commented 2025-03-07 17:54:36 +01:00
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ls /dev/tcp/127.0.0.1/22

ls: cannot access '/dev/tcp/127.0.0.1/22': No such file or directory

but have a similar output as the Super User answer 622641 with cat.

```bash ls /dev/tcp/127.0.0.1/22 ``` ``` ls: cannot access '/dev/tcp/127.0.0.1/22': No such file or directory ``` but have a similar output as [the Super User answer 622641](https://superuser.com/a/622641) with `cat`.
Benjamin_Loison commented 2025-03-07 17:56:12 +01:00
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echo -n > /dev/tcp/localhost/22
echo $?

0

echo -n > /dev/tcp/localhost/22222

bash: connect: Connection refused
bash: /dev/tcp/localhost/22222: Connection refused

echo $?

1
```bash echo -n > /dev/tcp/localhost/22 echo $? ``` ``` 0 ``` ```bash echo -n > /dev/tcp/localhost/22222 ``` ``` bash: connect: Connection refused bash: /dev/tcp/localhost/22222: Connection refused ``` ```bash echo $? ``` ``` 1 ```
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Reference: Benjamin_Loison/linux#38