pycdpd

Cisco Discovery Protocol (CDP) daemon written in Python.

About

This daemon implements a simple version of the Cisco Discovery Protocol (CDP).

Manual Installation

Clone the repository.

git clone https://github.com/frei-style/pycdpd

Change into the working copy.

cd pycdpd

Copy the daemon.

sudo cp pycdpd /usr/local/bin/

Copy the service file for systemd.

sudo cp systemd/pycdpd.service /etc/systemd/system/

Correct the permissions.

sudo chmod 700 /usr/local/bin/pycdpd
sudo chmod 644 /etc/systemd/system/pycdpd.service

Reload systemd.

systemctl daemon-reload

Enable the service.

systemctl enable pycdpd

Start the service.

systemctl start pycdpd

Usage

usage: pycdpd [-h] [-i INTERFACE [INTERFACE ...]] [--interval [0-300]]
              [-s SOFTWARE_VERSION] [-p PLATFORM] [-d DEVICEID] [-r REQUEST]
              [--debug]

Send CDP packages.

optional arguments:
  -h, --help            show this help message and exit
  -i INTERFACE [INTERFACE ...], --interface INTERFACE [INTERFACE ...]
                        interface to sende to packet out. (default: all)
  --interval [0-300]    Interval in seconds. If greater than 0, packages will
                        be sent until the program is terminated. (default: 60)
  -s SOFTWARE_VERSION, --software-version SOFTWARE_VERSION
                        Set the software-version string manually (default:
                        autodetect)
  -p PLATFORM, --platform PLATFORM
                        Set the platform string manually (default: autodetect)
  -d DEVICEID, --deviceid DEVICEID
                        Set the device string manually (default: autodetect)
  -r REQUEST, --request REQUEST
                        Set the request id for PoE budget requests. Daemon
                        will stop after sending PoE budget ACK for 20 Watts.
                        Use it only with 802.3at midspan!
  --debug               For debuging: print a message when a package is sent.

Examples

Package in Wireshark

Package in tcpdump

[root@samantha ~]# tcpdump -n -i bond0.666 'ether host 01:00:0c:cc:cc:cc and ether[16:4] = 0x0300000C and ether[20:2] == 0x2000' -vvvv
tcpdump: listening on bond0.666, link-type EN10MB (Ethernet), capture size 262144 bytes
23:35:13.589382 CDPv2, ttl: 180s, checksum: 0x340e (unverified), length 173
        Device-ID (0x01), value length: 8 bytes: 'samantha'
        Version String (0x05), value length: 101 bytes: 
          Red Hat Enterprise Linux Server 8.2 (Ootpa)
          Linux-4.18.0-193.el8.x86_64-x86_64-with-redhat-8.2-Ootpa
        Platform (0x06), value length: 35 bytes: 'HPE ProLiant DL380 Gen10 (**********)'
        Port-ID (0x03), value length: 9 bytes: 'bond0.666'

Links

• Cisco White Paper: Device Discovery Protocols
• Cisco: Cisco Discovery Protocol Version 2
• Wireshark: Cisco Discovery Protocol (CDP)
• Data Network Resource: Cisco Discovery Protocol (CDP)

Disclaimer

I'm not a programmer and I'm not a network expert. Use at your own risk.

TODO

• Support more information like ip addresses, vlan
• Tests
• Code documentation
• A lot of refactoring
• Packages: deb, rpm, pip