chore(kb/netcat): revise article, split by userland

knowledge base/gnu userland/netcat.md

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+# Netcat
+
+> TODO
+
+Intro
+
+1. [TL;DR](#tldr)
+1. [Further readings](#further-readings)
+
+## TL;DR
+
+<details>
+  <summary>Setup</summary>
+
+```sh
+brew install 'netcat'
+```
+
+</details>
+
+<details>
+  <summary>Usage</summary>
+
+```sh
+# Listen (server mode).
+netcat --listen --local-port '8080'
+nc -lp '8080'
+```
+
+</details>
+
+<!-- Uncomment if used
+<details>
+  <summary>Real world use cases</summary>
+
+```sh
+```
+
+</details>
+-->
+
+## Further readings
+
+- [Website]
+- [Codebase]
+
+<!--
+  Reference
+  ═╬═Time══
+  -->
+
+<!-- In-article sections -->
+<!-- Knowledge base -->
+<!-- Files -->
+<!-- Upstream -->
+[Codebase]: https://sourceforge.net/p/netcat/code/HEAD/tree/
+[Website]: https://netcat.sourceforge.net/
+
+<!-- Others -->

knowledge base/netcat.md

@@ -1,55 +0,0 @@
-# Netcat
-
-1. [TL;DR](#tldr)
-1. [Further readings](#further-readings)
-   1. [Sources](#sources)
-
-## TL;DR
-
-Options of interest:
-
-- `-N`: close the network socket when finished; not available in nmap's netcat
-- `-l`: bind to the port and listen for incoming connections (server mode)
-- `-n`: do not resolve hostnames via DNS
-- `-p`: specify the source port to use
-- `-t`: use telnet negotiation
-- `-u`: use UDP
-- `-v`: set verbosity level; can be used several times
-- `-w=SECS`: timeout for connects and final net reads, in seconds
-- `-z`: zero-I/O mode, exit once connected
-
-```sh
-# Install
-dnf install 'nmap-ncat'
-yum install 'nmap-ncat'
-
-# Check ports on hosts.
-nc -Nnvz 192.168.0.81 22-25
-nc -Nvz host.name 443
-nc -Nvz -u dns.server 123
-
-# List hosts with a specific port open.
-# But you might just want to use `nmap`.
-parallel -j 0 "nc -Nnvz -w 2 192.168.0.{} 22 2>&1" ::: {2..254} \
-| grep -v "timed out"
-
-# Wait for a host to be up.
-until nc -Nvz -w 3 pi.lan 22; do sleep 3; done
-
-# Listen mode.
-nc -l 5666
-```
-
-## Further readings
-
-### Sources
-
-- [How To use Netcat to establish and test TCP and UDP connections]
-
-<!--
-  Reference
-  ═╬═Time══
-  -->
-
-<!-- Others -->
-[how to use netcat to establish and test tcp and udp connections]: https://www.digitalocean.com/community/tutorials/how-to-use-netcat-to-establish-and-test-tcp-and-udp-connections

knowledge base/nmap's netcat.md

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+# Nmap's netcat
+
+1. [TL;DR](#tldr)
+1. [Further readings](#further-readings)
+   1. [Sources](#sources)
+
+## TL;DR
+
+Options of interest:
+
+| Option              | Summary                                                                           |
+| ------------------- | --------------------------------------------------------------------------------- |
+| `-l`, `--listen`    | bind to the port given in input and listen for incoming connections (server mode) |
+| `-k`, `--keep-open` | accept multiple connections in listen mode                                        |
+| `-n`, `--nodns`     | do not resolve hostnames via DNS                                                  |
+| `-p`                | specify the source port to use                                                    |
+| `-t`                | use telnet negotiation                                                            |
+| `-u`                | use UDP                                                                           |
+| `-v`                | set verbosity level; can be used several times                                    |
+| `-w=SECS`           | timeout for connects and final net reads, in seconds                              |
+| `-z`                | zero-I/O mode, exit once connected                                                |
+
+```sh
+# Install
+brew install 'nmap'
+dnf install 'nmap-ncat'
+yum install 'nmap-ncat'
+
+# Check ports on hosts.
+nc -Nnvz 192.168.0.81 22-25
+nc -Nvz host.name 443
+nc -Nvz -u dns.server 123
+
+# List hosts with a specific port open.
+# But you might just want to use `nmap`.
+parallel -j 0 "nc -Nnvz -w 2 192.168.0.{} 22 2>&1" ::: {2..254} \
+| grep -v "timed out"
+
+# Wait for a host to be up.
+until nc -Nvz -w 3 pi.lan 22; do sleep 3; done
+
+# Server mode.
+nc -l 5666
+nc -lk 8080
+```
+
+## Further readings
+
+### Sources
+
+- [How To use Netcat to establish and test TCP and UDP connections]
+
+<!--
+  Reference
+  ═╬═Time══
+  -->
+
+<!-- Others -->
+[how to use netcat to establish and test tcp and udp connections]: https://www.digitalocean.com/community/tutorials/how-to-use-netcat-to-establish-and-test-tcp-and-udp-connections