Added TL;DR for tcpdump

knowledge base/tcpdump.md

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+# tcpdump
+
+## TL;DR
+
+```sh
+# Get all packets in and out of an interface.
+tcpdump -i 'eth0'
+
+# Get all packets to or from a host.
+tcpdump host '1.1.1.1'
+
+# Get all packets from a source or for a destination.
+tcpdump src '1.1.1.1'
+tcpdump dst '1.0.0.1'
+
+# Get all packets to or from a network.
+tcpdump net '1.2.3.0/24'
+
+# Get packets to or from ports.
+tcpdump port '3389'
+tcpdump portrange '21-23'
+
+# Get packets of a protocol.
+tcpdump icmp
+
+# Get packages based on their size.
+tcpdump less '32'
+tcpdump greater '64'
+tcpdump <= '128'
+
+# Combine filters.
+tcpdump src port '1025'
+tcpdump -nnvvS src '10.5.2.3' and dst port '3389'
+tcpdump -nX src net '192.168.0.0/16' and dst net '10.0.0.0/8' or '172.16.0.0/16'
+tcpdump dst '192.168.0.2' and src net and not icmp
+tcpdump -vv src 'mars' and not dst port '22'
+tcpdump 'src 10.0.2.4 and (dst port 3389 or 22)'
+
+# Save results to a file.
+tcpdump port '80' -w 'path/to/capture.file'
+
+# Read packets from a file.
+tcpdump -r 'path/to/capture.file'
+
+# Isolate TCP flags.
+tcpdump 'tcp[tcpflags] == tcp-fin'
+```
+
+## Sources
+
+- [A tcpdump tutorial with examples — 50 ways to isolate traffic]
+
+<!-- project's references -->
+<!-- internal references -->
+<!-- external references -->
+[a tcpdump tutorial with examples — 50 ways to isolate traffic]: https://danielmiessler.com/study/tcpdump/