= Network analysis !
Apostolos rootApostolos@swarmlab.io
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:description: Intro and Install
:keywords: sec, tcpdump
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:toc-title: Πίνακας περιεχομένων
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[[cheat-Docker]]
== Install swarmlab-sec (Home PC)

HowTo: See http://docs.swarmlab.io/lab/sec/sec.adoc.html


.NOTE
[NOTE]
====
Assuming you're already logged in
====


**tcpdump** is a common packet analyzer that runs under the command line. It allows the user to display TCP/IP and other packets being transmitted or received over a network to which the computer is attached. Distributed under the BSD license, tcpdump is free software. 

https://en.wikipedia.org/wiki/Tcpdump[More: wikipedia]

== Basic

=== Everything on an interface

Just see what’s going on, by looking at what’s hitting your interface.

[source,bash]
----
tcpdump -i eth0
----

=== Find Traffic by IP

One of the most common queries, using host, you can see traffic that’s going to or from 1.1.1.1.

[source,bash]
----
tcpdump host 1.1.1.1
----


=== Filtering by Source and/or Destination

If you only want to see traffic in one direction or the other, you can use src and dst.

[source,bash]
----
tcpdump src 1.1.1.1
tcpdump dst 1.0.0.1
----

=== Finding Packets by Network

To find packets going to or from a particular network or subnet, use the net option.

[source,bash]
----
tcpdump net 1.2.3.0/24
----


=== Show Traffic Related to a Specific Port

You can find specific port traffic by using the port option followed by the port number.

[source,bash]
----
tcpdump port 3389
tcpdump src port 1025
----

=== Show Traffic of One Protocol

If you’re looking for one particular kind of traffic, you can use tcp, udp, icmp, and many others as well.

[source,bash]
----
tcpdump icmp
----

=== Reading / Writing Captures to a File (pcap)

It’s often useful to save packet captures into a file for analysis in the future. These files are known as PCAP (PEE-cap) files, and they can be processed by hundreds of different applications, including network analyzers, intrusion detection systems, and of course by tcpdump itself. Here we’re writing to a file called capture_file using the -w switch.


[source,bash]
----
tcpdump port 80 -w capture_file
----


== Advanced












[appendix]
== How to use tcpdump


This exercise will show you how to isolate traffic in various ways—from IP, to port, to protocol, to application-layer traffic—to make sure you find exactly what you need as quickly as possible.







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'''

.Reminder
[NOTE]
====
:hardbreaks:
Caminante, no hay camino, 
se hace camino al andar.

Wanderer, there is no path, 
the path is made by walking.

*Antonio Machado* Campos de Castilla
====
