## Documentation

## Index

1. Important notice
2. What is ArpON?
3. Features
4. Supported Operating Systems
5. Required software and libraries
6. Stable release via the HTTP mirror
7. Version
8. Changelog
9. Building and installation
10. Upgrade
11. Quick start
12. ArpON daemon
13. Important note
14. Options summary
15. Files
16. Examples
17. How to use ArpON
18. Uninstallation
19. Support the development
20. Development release via the GIT repository
21. Activity diagrams
22. Compile time bugs
23. Runtime bugs
24. Support the project
25. Author
26. Copyright and licensing
27. Thanks
28. Reference website
29. Notes

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## 1. Important notice

Since ArpON 3.0-ng (next generation), ArpON has been rewritten from scratch, therefore all the old versions of ArpON (lower of 3.0-ng) are deprecated. Please upgrade all installations of ArpON and read carefully this documentation and the man page specified below of ArpON.

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## 2. What is ArpON?

ArpON (ARP handler inspection) is a Host-based solution that make the ARP standardized protocol secure in order to avoid the Man In The Middle (MITM) attack through the ARP spoofing, ARP cache poisoning or ARP poison routing attack.
This is possible using three kinds of anti ARP spoofing techniques:

1. SARPI (Static ARP Inspection) for the statically configured networks without DHCP;
2. DARPI (Dynamic ARP Inspection) for the dynamically configured networks with DHCP;
3. HARPI (Hybrid ARP Inspection) for the statically and dynamically configured networks with DHCP.

The goal of ArpON is therefore to provide a secure and efficient network daemon that provides the SARPI, DARPI and HARPI anti ARP spoofing technique, thus making the ARP standardized protocol secure from any foreign intrusion.

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## 3. Features

The features of ArpON are:

- Free. ArpON is released under the BSD open source license. This means that you have total freedom to modify and use it with your system, even if it's commercial.
- Popular. ArpON is used as the network daemon by many users, both the network managers and academic researchers. ArpON is downloaded several hundred of times every month.
- Tested and reliable. Many users have contributed over the years in testing ArpON on a wide range of Man In The Middle (MITM) attack tools through the ARP spoofing, ARP cache poisoning or ARP poison routing.
- Easy to use. ArpON is distributed as a single tarball that once compiled, runs on every supported Operating System. You launch the executable, and from that moment the Operating System is able to avoid the Man In The Middle (MITM) attack through the ARP spoofing, ARP cache poisoning or ARP poison routing.
- Multi-platform. Many developers have contributed over the years in porting ArpON on a wide range of GNU/Linux distributions.
- Compatible and portable. ArpON is completely compatible with the ARP standardized protocol. ArpON is an network daemon that runs in user space, this also means that ArpON will be easily portable to other Operating Systems.
- Well documented. The documentation of ArpON is easy and complete. The documentation contains the retrieving tutorial; the building tutorial; the installation tutorial; the user tutorial with many examples and scenarios; the development tutorial with the Activity diagrams of the SARPI, DARPI and HARPI anti ARP spoofing technique and with modular source code well commented; the bug report tutorial that takes you step-by-step through all of the features of ArpON.

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## 4. Supported Operating Systems

ArpON supports the GNU/Linux Operating System and a wide range of distributions.

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## 5. Required software and libraries

The source code compilation of the stable release of ArpON requires the following software and libraries installed in the System:

- GNU Binutils
- GNU C Compiler (GCC)
- Cmake 2.6 (or higher)
- GNU Make
- GNU C Library (Glibc) with POSIX Threads (Pthreads)
- GNU C Library (Glibc) with Realtime Extensions (Librt)
- Libpcap with development libraries 1.0.0 (or higher)
- Libnet1 with development libraries 1.1.2.1 (or higher)
- Libdnet with development libraries 1.11 (or higher)

The development release of ArpON also requires the following software installed in the System:

- Git
- GNU C Debugger (GDB)

The documentation of ArpON also requires the following software installed in the System:

- Visual Paradigm
- OpenOffice Draw
- VRT Network Equipment

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## 6. Stable release via the HTTP mirror

The latest stable release of ArpON is available via the HTTP mirror, please follow these steps:

1. First you have to download the tarball via the HTTP mirror:
   `$ wget http://sourceforge.net/projects/arpon/files/latest/download -O arpon.tar.gz`
2. After you have successfully downloaded the tarball, download the MD5 file of the tarball via the HTTP mirror:
   `$ wget http://sourceforge.net/projects/arpon/files/latest.md5/download -O latest.md5`
3. Generate the MD5 of your tarball downloaded:
   `$ md5sum arpon.tar.gz | awk '{print $1}' > arpon.md5`
4. Validate the MD5 of your tarball downloaded:
   `$ diff -u latest.md5 arpon.md5`
   If you have not the output of the diff, the tarball downloaded is valid.
5. If the tarball si valid, untar the tarball downloaded:
   `$ mkdir arpon
   $ tar -xvzf arpon.tar.gz -C arpon --strip-components=1`
6. After you have successfully downloaded and validated the tarball then you must initiate the building and installation.

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## 7. Version

The version of ArpON is available in:

`$ cat /path/to/arpon/VERSION`

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## 8. Changelog

The changelog of ArpON is available in:

`$ cat /path/to/arpon/CHANGELOG`

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## 9. Building and installation

To build and install the ArpON, please follow these steps:

- To install the ArpON in the default "/" path:
  `$ cd /path/to/arpon
  $ mkdir build
  $ cd build
  $ cmake ..
  $ make
  $ sudo make install`
- To install the ArpON in an other path:
  `$ cd /path/to/arpon
  $ mkdir build
  $ cd build
  $ cmake -DCMAKE_INSTALL_PREFIX="/path/to/install" ..
  $ make
  $ sudo make install`
  Usually the paths of the installation are: "/", "/usr" or "/usr/local".
- If the your dependencies are installed in the other paths:
  `$ cd /path/to/arpon
  $ mkdir build
  $ cd build
  $ cmake -DCMAKE_INCLUDE_PATH="/path/to/include1;/path/to/include2" \
  -DCMAKE_LIBRARY_PATH="/path/to/library1;/path/to/library2" ..
  $ make
  $ sudo make install`
- If you want personalize the CFLAGS compiler parameters:
  `$ cd /path/to/arpon
  $ mkdir build
  $ cd build/
  $ cmake -DCMAKE_C_FLAGS="your-cflags-here" ..
  $ make
  $ sudo make install`

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## 10. Upgrade

To upgrade the ArpON, please follow the steps of the building and installation (with the same path of your previous installation of ArpON) that will overwrite all the files of ArpON.

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## 11. Quick start

To start quickly with ArpON, please follow these guidelines:

1. See the documentation file of ArpON. It contains the retrieving tutorial; the building tutorial; the installation tutorial; the user tutorial with many examples and scenarios; the development tutorial with the Activity diagrams of the SARPI, DARPI and HARPI anti ARP spoofing technique and with modular source code well commented; the bug report tutorial that takes you step-by-step through all of the features of ArpON. Please note that:
   If you chose the default "/" path of the installation, open with a browser web this file:
   `/usr/share/doc/arpon/index.html`
   Else open with a browser web this file:
   `PATH/share/doc/arpon/index.html`
   where PATH is the path of your installation.
2. See the man page of ArpON:
   `$ man 8 arpon`
3. See the help screen of ArpON:
   `$ sudo arpon -h`

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## 12. ArpON daemon

The synopsis of ArpON daemon command is:

`arpon [OPTIONS] [SARPI | DARPI | HARPI]`
ArpON sets of policies in the ARP cache for all the static and or dynamic entries matching the specified network interface (or that matching the several specified network interfaces if run concurrently several daemons of ArpON for different network interfaces), through the run of SARPI, DARPI or HARPI anti ARP spoofing technique.
ArpON have to be run with the root privileges. ArpON have to be configured using command-line options and a configuration file. ArpON reloads the configuration of the specified network interface and rereads its configuration file when it receives a hangup signal (SIGHUP) by executing itself with the name and options it was started with. ArpON exits correctly when it receives an interrupt signal (SIGINT) or a termination signal (SIGTERM).

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## 13. Important note

The ArpON daemon sets two fundamental kernel network parameters via the sysctl interface on the specified network interface:

1. The arp_ignore kernel parameter of the specified network interface is always setted to 8 by ArpON. This is done to disable, in the specified network interface of the Operating System, the sending of the ARP replies in response to received ARP requests for all local addresses (the ARP replies on the specified network interface, will be sent by ArpON instead of the Operating System).
2. The arp_accept kernel parameter of the specified network interface is always setted to 0 by ArpON. This is done to disable, in the specified network interface of the Operating System, the creating of the new IP entries in the ARP cache triggered by the unsolicited and gratuitous ARP requests and replies (the IP entries in the ARP cache on the specified network interface, will be created or updated by ArpON as static or dynamic IP entries instead of the Operating System).

The ArpON daemon restores the previously values read from the arp_ignore and arp_accept kernel parameters of the specified network interface when it receives an interrupt signal (SIGINT) or a termination signal (SIGTERM). Remember to restore the values of the arp_ignore and arp_accept kernel parameters of the specified network interface (the default values are 0 for both), if you have terminated the ArpON daemon with other signals, e.g. kill signal (SIGKILL).

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## 14. Options summary

The available options of ArpON daemon command are:

- General options:
  `-d, --daemon
  Daemonize the ArpON.
  -i, --interface <interface>
  Use the specified network interface.`
- SARPI 'Static ARP Inspection' option:
  SARPI anti ARP spoofing technique manages and sets the policies in the ARP cache only for all the static entries matching the specified network interface, in order to avoid the Man In The Middle (MITM) attack through the ARP spoofing, ARP cache poisoning or ARP poison routing. Therefore SARPI is an optimal choice in those statically configured networks without DHCP. SARPI sets these policies:
  1. CLEAN: SARPI cleans from the ARP cache only all the entries matching the specified network interface, that are present or not present in the configuration file;
  2. UPDATE: SARPI updates in the ARP cache only all the static entries matching the specified network interface, that are present in the configuration file;
  3. REFRESH: SARPI refreshes in the ARP cache only a static entry matching the specified network interface, that is present in the configuration file;
  4. ALLOW: SARPI sets up in the ARP cache only a dynamic entry matching the specified network interface, that is not present in the configuration file.
  Therefore SARPI requires a specified network interface and the specification in the configuration file of the ARP cache only for all the static entries matching the specified network interface.
  `-S, --sarpi
  Run SARPI anti ARP spoofing technique.`
- DARPI 'Dynamic ARP Inspection' option:
  DARPI anti ARP spoofing technique manages and sets the policies in the ARP cache only for all the dynamic entries matching the specified network interface, in order to avoid the Man In The Middle (MITM) attack through the ARP spoofing, ARP cache poisoning or ARP poison routing. Therefore DARPI is an optimal choice in those dynamically configured networks with DHCP. DARPI sets these policies:
  1. CLEAN: DARPI cleans from the ARP cache only all the entries matching the specified network interface;
  2. ALLOW: DARPI sets up in the ARP cache only a dynamic entry matching the specified network interface;
  3. DENY: DARPI cleans up from the ARP cache only a dynamic entry matching the specified network interface.
  Therefore DARPI requires a specified network interface and it doesn't requires any specification in the configuration file of the ARP cache only for all the dynamic entries matching the specified network interface.
  `-D, --darpi
  Run DARPI anti ARP spoofing technique.`
- HARPI 'Hybrid ARP Inspection' option:
  HARPI anti ARP spoofing technique manages and sets the policies in the ARP cache for both all the static and dynamic entries matching the specified network interface, in order to avoid the Man In The Middle (MITM) attack through the ARP spoofing, ARP cache poisoning or ARP poison routing. Therefore HARPI is an optimal choice in those statically and dynamically configured networks with DHCP. HARPI sets and combines these policies of the SARPI and DARPI:
  1. CLEAN: HARPI cleans from the ARP cache only all the entries matching the specified network interface, that are present or not present in the configuration file;
  2. UPDATE: HARPI updates in the ARP cache only all the static entries matching the specified network interface, that are present in the configuration file;
  3. REFRESH: HARPI refreshes in the ARP cache only a static entry matching the specified network interface, that is present in the configuration file;
  4. ALLOW: HARPI sets up in the ARP cache only a dynamic entry matching the specified network interface, that is not present in the configuration file;
  5. DENY: HARPI cleans up from the ARP cache only a dynamic entry matching the specified network interface, that is not present in the configuration file.
  Therefore HARPI requires a specified network interface, the specification in the configuration file of the ARP cache only for all the static entries matching the specified network interface; instead it doesn't requires any specification in the configuration file of the ARP cache only for all the dynamic entries matching the specified network interface.
  `-H, --harpi
  Run HARPI anti ARP spoofing technique.`
- Standard options:
  `-v, --version
  Print the version and exit.
  -h, --help
  Print the help screen and exit.`

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## 15. Files

The available files of ArpON daemon command are:

- The configuration file contains the configuration data of ArpON and it is used when run the SARPI or HARPI anti ARP spoofing technique, for the specification in the ARP cache only for all the static entries matching the specified network interface (or that matching the several specified network interfaces if run concurrently several daemons of ArpON for different network interfaces). This file should be writable by root only but it is recommended (though not necessary) that it be world-readable. Please note that:
  If you chose the default "/" path of the installation, the configuration file is:
  `/etc/arpon.conf`
  Else the configuration file is:
  `PATH/etc/arpon.conf`
  where PATH is the path of your installation.
- The log file contains the log data of ArpON. If there are several daemons of ArpON running concurrently for different network interfaces, this contains the log data of all the daemons of ArpON. This file should be readable only by root, and need not be readable by anyone else. Please note that:
  If you chose the default "/" path of the installation, the log file is:
  `/var/log/arpon.log`
  Else the log file is:
  `PATH/log/arpon.log`
  where PATH is the path of your installation.
- The pid file contains the process ID of ArpON. If there are several daemons of ArpON running concurrently for different network interfaces, this contains the process ID of the one started last. The content of this file is not sensitive; it can be world-readable. Please note that:
  If you chose the default "/" path of the installation, the pid file is:
  `/var/run/arpon.pid`
  Else the pid file is:
  `PATH/run/arpon.pid`
  where PATH is the path of your installation.

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## 16. Examples

These examples shows how to use all three kinds of anti ARP spoofing techniques of ArpON daemon. Note that these examples use the default "/" path of the installation of the files.
In the same host, we have three network interfaces with different subnet classes and we would set the ARP cache for all the static and dynamic entries matching the eth0, wlan0 and eth1 network interfaces. This scenario requires the run concurrently of three daemons of ArpON:

- SARPI 'Static ARP Inspection' example:
  The eth0 network interface has the 192.168.1.2/24 IP address. We have only three static entries of the ARP cache:
  1. 192.168.1.1 at 58:ac:78:10:b9:77;
  2. 192.168.1.3 at d4:be:d9:fe:8b:45;
  3. 192.168.1.4 at 90:94:e4:bb:1c:10.
  and we have no dynamic entries of the ARP cache. This is the ideal case where we have to use the SARPI anti ARP spoofing technique, therefore specify in the configuration file of the ARP cache only all the static entries matching the eth0 network interface:
  `$ sudo nano /etc/arpon.conf`
  Therefore:
  `#
  # ArpON configuration file.
  #
  # See the arpon(8) man page for details.
  #
  #
  # Static entries matching the eth0 network interface:
  #
  # First static entry:
  192.168.1.1 58:ac:78:10:b9:77
  # Second static entry:
  192.168.1.3 d4:be:d9:fe:8b:45
  # Third static entry:
  192.168.1.4 90:94:e4:bb:1c:10`
  Daemonize the ArpON and run SARPI anti ARP spoofing technique on the eth0 network interface:
  `$ sudo arpon -d -i eth0 -S`
  Read the log file:
  `$ sudo tail -f /var/log/arpon.log`
  Read the pid file:
  `$ cat /var/run/arpon.pid`
- DARPI 'Dynamic ARP Inspection' example:
  The wlan0 network interface has the 172.16.1.2/24 IP address. We have no static entries of the ARP cache, and we have only dynamic entries of the ARP cache. This is the ideal case where we have to use the DARPI anti ARP spoofing technique, therefore daemonize the ArpON and run DARPI anti ARP spoofing technique on the wlan0 network interface:
  `$ sudo arpon -d -i wlan0 -D`
  Read the log file:
  `$ sudo tail -f /var/log/arpon.log`
  Read the pid file:
  `$ cat /var/run/arpon.pid`
- HARPI 'Hybrid ARP Inspection' example:
  The eth1 network interface has the 10.0.1.2/16 IP address. We have only two static entries of the ARP cache:
  1. 10.0.1.1 at 58:ac:78:88:1a:bb;
  2. 10.0.10.1 at 90:94:e4:7e:f4:59.
  and we have the rest of entries as dynamic entries of the ARP cache. This is the ideal case where we have to use the HARPI anti ARP spoofing technique, therefore specify in the configuration file of the ARP cache only all the static entries matching the eth1 network interface:
  `$ sudo nano /etc/arpon.conf`
  Therefore:
  `#
  # ArpON configuration file.
  #
  # See the arpon(8) man page for details.
  #
  #
  # Static entries matching the eth0 network interface:
  #
  # First static entry:
  192.168.1.1 58:ac:78:10:b9:77
  # Second static entry:
  192.168.1.3 d4:be:d9:fe:8b:45
  # Third static entry:
  192.168.1.4 90:94:e4:bb:1c:10
  #
  # Static entries matching the eth1 network interface:
  #
  # First static entry:
  10.0.1.1 58:ac:78:88:1a:bb
  # Second static entry:
  10.0.10.1 90:94:e4:7e:f4:59`
  Daemonize the ArpON and run HARPI anti ARP spoofing technique on the eth1 network interface:
  `$ sudo arpon -d -i eth1 -H`
  Read the log file:
  `$ sudo tail -f /var/log/arpon.log`
  Read the pid file:
  `$ cat /var/run/arpon.pid`

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## 17. How to use ArpON

The available scenarios of ArpON, that explain respectively how ArpON works and how to use ArpON are:

- Half-duplex ArpON defense:
  This scenario shows the half-duplex Man In The Middle (half-duplex MITM) attack through the ARP spoofing. The attacker is attacking only the host A, therefore the attacker is intercepting only the communications from the host A to host B:
  Open this Network diagram as [JPG | PDF | ODG].
  Run the ArpON only in the host A in order to avoid the half-duplex attack:
  Open this Network diagram as [JPG | PDF | ODG].
  The communications between the host A and the host B are back again secure, leaving the attacker out.

- Full-duplex ArpON defense:
  This scenario shows the full-duplex Man In The Middle (full-duplex MITM) attack through the ARP spoofing. The attacker is attacking both the host A and the host B, therefore the attacker is intercepting all the communications between the host A and the host B:
  Open this Network diagram as [JPG | PDF | ODG].
  Run the ArpON only in the host A in order to avoid the half-duplex attack:
  Open this Network diagram as [JPG | PDF | ODG].
  The communications from the host A to host B are back again secure, leaving the attacker out. Finally, run the ArpON also in the host B in order to avoid the full-duplex attack:
  Open this Network diagram as [JPG | PDF | ODG].
  The communications between the host A and the host B are back again secure, leaving the attacker out.

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## 18. Uninstallation

To uninstall ArpON:

`$ cd /path/to/arpon/build
$ sudo make uninstall`

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## 19. Support the development

If you are a developer and you wish write any fix, feature or OS port of ArpON, please follow these steps, make it available under the BSD open source license and contribute to the project sending the patch:

1. Clone or pull via the GIT repository and use the latest development release of ArpON.
2. Understand the Activity diagrams of ArpON, that explain respectively the algorithms and the policies of SARPI, DARPI and HARPI anti ARP spoofing technique.
3. Create a new devel branch and personalize the build type from Release to Debug:
   `$ cd /path/to/arpon
   $ git checkout -b devel
   $ mkdir debug
   $ cd debug
   $ cmake -DCMAKE_BUILD_TYPE="debug" ..
   $ make VERBOSE=1`
4. Before to see any codes, study and adhere the FreeBSD encoding standard.
5. Write any fix, feature or OS port for ArpON and test it in Debug build type:
   `$ cd /path/to/arpon
   $ vim file_to_edit_1 file_to_edit_2 file_to_edit_N
   $ cd /path/to/arpon/debug
   $ make VERBOSE=1
   $ sudo make install
   $ sudo arpon [OPTIONS] [SARPI | DARPI | HARPI]`
6. Switch the build type from Debug to Release and test, test and test it again in Release build type:
   `$ cd /path/to/arpon/debug
   $ sudo make uninstall
   $ cd ..
   $ mkdir release
   $ cd release
   $ cmake -DCMAKE_BUILD_TYPE="release" ..
   $ make
   $ sudo make install
   $ sudo arpon [OPTIONS] [SARPI | DARPI | HARPI]`
7. Commit the changes into devel branch and create the patch:
   `$ cd /path/to/arpon/
   $ rm -Rf debug release
   $ git add -A
   $ git commit -m "Describe your patch"
   $ git format-patch master --stdout > patch.diff`
8. Send the created patch.diff file with any details to author or via the Bug tracking system.
9. The author will review the code, make any necessary changes and merge the code into the proper branch.
10. You will receive full credit as a contributor to the project.

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## 20. Development release via the GIT repository

The latest development release of ArpON is available via the GIT repository, please follow these steps:

1. First you have to clone the project via the GIT repository:
   `$ git clone git://git.code.sourceforge.net/p/arpon/code arpon
   $ cd arpon`
   Or via the GIT repository over HTTP protocol:
   `$ git clone http://git.code.sourceforge.net/p/arpon/code arpon
   $ cd arpon`
2. If you already had the repository cloned, you will need to pull the latest changes:
   `$ cd /path/to/arpon
   $ git pull`
3. After you have successfully cloned or pulled the repository then you must initiate the building and installation.

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## 21. Activity diagrams

All the available algorithms of ArpON are compatible with the ARP standardized protocol as described in these official RFC documents:

1. RFC 826;
2. RFC 2131;
3. RFC 3927;
4. RFC 5227.

Note that all the available algorithms of ArpON set the arp_ignore and the arp_accept fundamental kernel network parameters via the sysctl interface as described in this official kernel document:

1. IP sysctl.

Therefore the available Activity diagrams of ArpON, that explain respectively the algorithms and the policies of all three kinds of anti ARP spoofing techniques are:

- SARPI 'Static ARP Inspection' Activity diagram:
  Open this Activity diagram as [JPG | PDF | VPP].

To understand the SARPI 'Static ARP Inspection' Activity diagram, it is very important to understand this network diagram, that show a simple case of execution of the SARPI algorithm, in order to permit the communication between the host A (with a static IP address) and the host B (with a static IP address):
Open this network diagram as [JPG | PDF | ODG].

Instead this network diagram shows a simple case of execution of the SARPI algorithm, in order to permit the communication between the host A (with a static IP address) and the host B (with a static IP address), leaving the host C (attacker) out from the communication:
Open this network diagram as [JPG | PDF | ODG].

- DARPI 'Dynamic ARP Inspection' Activity diagram:
  Open this Activity diagram as [JPG | PDF | VPP].

To understand the DARPI 'Dynamic ARP Inspection' Activity diagram, it is very important to understand this network diagram, that show a simple case of execution of the DARPI algorithm, in order to permit the communication between the host A (with a dynamic IP address) and the host B (with a dynamic IP address), checking any network errors:
Open this network diagram as [JPG | PDF | ODG].

Instead this network diagram shows a simple case of execution of the DARPI algorithm, in order to permit the communication between the host A (with a dynamic IP address) and the host B (with a dynamic IP address), leaving the host C (attacker) out from the communication:
Open this network diagram as [JPG | PDF | ODG].

- HARPI 'Hybrid ARP Inspection' Activity diagram that combines the SARPI and DARPI Activity diagram:
  Open this Activity diagram as [JPG | PDF | VPP].

To understand the HARPI 'Hybrid ARP Inspection' Activity diagram, it is very important to understand these network diagrams, where the first one show a simple case of execution of the HARPI algorithm, in order to permit the communication between the host A (with a static IP address) and the host B (with a static IP address):
Open this network diagram as [JPG | PDF | ODG].

Instead this network diagram shows a simple case of execution of the HARPI algorithm, in order to permit the communication between the host A (with a static IP address) and the host B (with a static IP address), leaving the host C (attacker) out from the communication:
Open this network diagram as [JPG | PDF | ODG].

The second one show a simple case of execution of the HARPI algorithm, in order to permit the communication between the host A (with a dynamic IP address) and the host B (with a dynamic IP address), checking any network errors:
Open this network diagram as [JPG | PDF | ODG].

Instead this network diagram shows a simple case of execution of the HARPI algorithm, in order to permit the communication between the host A (with a dynamic IP address) and the host B (with a dynamic IP address), leaving the host C (attacker) out from the communication:
Open this network diagram as [JPG | PDF | ODG].

The third one show a simple case of execution of the HARPI algorithm, in order to permit the communication between the host A (with a dynamic IP address) and the host B (with a static IP address), checking any network errors:
Open this network diagram as [JPG | PDF | ODG].

Instead this network diagram shows a simple case of execution of the HARPI algorithm, in order to permit the communication between the host A (with a dynamic IP address) and the host B (with a static IP address), leaving the host C (attacker) out from the communication:
Open this network diagram as [JPG | PDF | ODG].

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## 22. Compile time bugs

If you are not able to compile ArpON on your System, please follow these steps to make a simple bug report in order to help us to find the bug and fix it:

1. Clean the ArpON build directory:
   `$ cd /path/to/arpon/build
   $ make clean-all`
2. Create the report directory:
   `$ mkdir /tmp/report`

We need the following informations:

1. A description of your Operating System:
   `$ uname -a > /tmp/report/os.log`
2. A description of your GNU/Linux distribution:
   If you have the lsb_release command:
   `$ lsb_release -a > /tmp/report/distro.log`
   Else if you have not the lsb_release command:
   `$ cp /etc/os-release /tmp/report/distro.log`
   Else if you have not the os-release file put your distribution name:
   `$ echo "your-distro-here" > /tmp/report/distro.log`
3. The version of ArpON:
   `$ cp ../VERSION /tmp/report`
4. The CMake cache file:
   `$ cmake ..
   $ cp CMakeCache.txt /tmp/report`
5. The entire output from make:
   `$ make VERBOSE=1 >> /tmp/report/make_out.log 2>> /tmp/report/make_err.log`
6. Make a tarball of your report:
   `$ cd /tmp
   $ tar -pcvzf report.tar.gz report
   report/
   report/distro.log
   report/os.log
   report/make_err.log
   report/CMakeCache.txt
   report/VERSION
   report/make_out.log`
7. Send the report.tar.gz tarball to author or via the Bug tracking system.

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## 23. Runtime bugs

If the bug is critical and results in a segmentation fault, please follow these steps to make a detailed bug report in order to help us to find the bug and fix it:

1. Recompile the ArpON in debug build type:
   `$ cd /path/to/arpon
   $ mkdir debug
   $ cd debug
   $ cmake -DCMAKE_BUILD_TYPE="debug" ..
   $ make
   $ sudo make install`
2. Create the report directory:
   `$ mkdir /tmp/report`

We need the following informations:

1. A description of your Operating System:
   `$ uname -a > /tmp/report/os.log`
2. A description of your GNU/Linux distribution:
   If you have the lsb_release command:
   `$ lsb_release -a > /tmp/report/distro.log`
   Else if you have not the lsb_release command:
   `$ cp /etc/os-release /tmp/report/distro.log`
   Else if you have not the os-release file put your distribution name:
   `$ echo "your-distro-here" > /tmp/report/distro.log`
3. The version of ArpON:
   `$ cp ../VERSION /tmp/report`
4. The stacktrace of ArpON that reproduces the bug:
   Override any limit for coredumps:
   `$ ulimit -c unlimited`
   Enter in the directory where there is the ArpON executable:
   If you chose the default "/" path of the installation, enter in:
   `$ cd /sbin`
   Else enter in:
   `$ cd PATH/sbin`
   where PATH is the path of your installation.
   Run the ArpON executable and reproduce the bug (it'll create the coredump):
   `$ sudo arpon your-parameters-here`
   Create the stacktrace of the bug with the gdb and the coredump:
   `$ sudo gdb --batch --quiet -ex "thread apply all bt full" -ex "quit" \
   arpon core >> /tmp/report/stacktrace.log 2>> /tmp/report/stacktrace.log`
   Please note that the path of the coredump depends by your OS setting.
5. The log file of ArpON:
   If you chose the default "/" path of the installation, copy this file:
   `$ cp /var/log/arpon.log /tmp/report`
   Else copy this file:
   `$ cp PATH/log/arpon.log /tmp/report`
   where PATH is the path of your installation.
6. Make a tarball of your report:
   `$ cd /tmp
   $ tar -pcvzf report.tar.gz report
   report/
   report/distro.log
   report/arpon.log
   report/os.log
   report/stacktrace.log
   report/VERSION`
7. Send the report.tar.gz tarball to author or via the Bug tracking system.

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## 24. Support the project

We are always happy about donations in any form.
If you are a corporate user, vendor or private user, we would gladly accept any donations, either monetary or in goods (network hardware, etc). We assure you that any donation we receive is very much appreciated and used for further development of ArpON software.
If you are interested in making a donation, please contact the author.

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## 25. Author

ArpON was writen by Andrea Di Pasquale aka "spikey" <spikey.it@gmail.com>.

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## 26. Copyright and licensing

Copyright © 2008-2016 Andrea Di Pasquale <spikey.it@gmail.com>
All rights reserved.
Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR HIS RELATIVES BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF MIND, USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

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## 27. Thanks

The list of the contributors to the project is available in:

`$ cat /path/to/arpon/THANKS`

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## 28. Reference website

The reference website of ArpON project is here.

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## 29. Notes

The ArpON daemon is completely compatible with the ARP standardized protocol as described in these official RFC documents:

1. RFC 826;
2. RFC 2131;
3. RFC 3927;
4. RFC 5227.

The ArpON daemon sets the arp_ignore and the arp_accept fundamental kernel network parameters via the sysctl interface as described in this official kernel document:

1. IP sysctl.

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