Endure

Endure is a DHCP diagnostics utility installed next to a server or relay. It analyzes the inbound and outbound DHCP traffic and collects various diagnostic metrics. It can also be used for the capture file analysis.

System and Software Requirements

Endure has been tested on Ubuntu 22 and macOS Sonoma 14.1.1. It requires libpcap library.

To compile the program on Ubuntu 22, first install lib Ipcap-dev:

$ apt install libpcap-dev

Building with Cargo

Endure is written in Rust and can be compiled using the cargo utility. It was tested with rustc version is 1.82.

$ cd endure
$ cargo build --release

The resulting binary can be found in the endure/target/release directory.

Running the Utility

Suppose your DHCP server is responding to the traffic on the interfaces bridge101 and bridge102. You can start monitoring the server with the following command:

$ endure collect -i bridge101 -i bridge102 -c stdout

The -c stdout argument configures the program to output collected metrics into the console periodically.

Listening on the local loopback interface has no practical application in production, however it may be useful for testing purposes. The --loopback switch is an alias for the -i [loopback name] (e.g., -i lo). However, the --loopback argument cannot be combined with -i.

$ endure collect --loopback -c stdout

Integration with Prometheus and Grafana

Endure source code includes a Docker Compose configuration that launches two containers, one with a Prometheus instance, and one with Grafana. This setup requires that Host network driver is enabled in Docker.

Launch the containers using the following commands:

$ cd docker
$ docker compose up

Prometheus is configured to scrape the metrics from http://localhost:9100. Make sure that endure makes the metrics available on that address and port. For example:

./endure collect --loopback  --prometheus --http-address 127.0.0.1:9100

Open Grafana dashboard in the browser on http://localhost:3000. Navigate to Dashboards to monitor the metrics exported by endure.

Capture File Analysis

Having a capture file named capture.pcap it is possible to gather the same metrics using the read command:

$ endure read --pcap capture.pcap --json

It will produce a report in the JSON format containing the metrics computed from all the DHCP packets in the capture file. The same report can be produced in the CSV format using the --csv switch.

Finally, using the --stream switch it is possible to generate a CSV output with several rows, each row presenting metrics for the number of packets specified using the --sampling-window-size switch. For example:

$ endure read --pcap capture.pcap --csv --stream --sampling-window-size 10

Metrics

Endure is a new project with limited capabilities. However, it can already collect and report several useful metrics:

Metric	Description
bootp_opcode_boot_requests_count	A total number of BootRequest messages
bootp_opcode_boot_replies_count	A total number of BootRequest messages
bootp_opcode_invalid_count	A total number of invalid messages (having invalid OpCode)
bootp_opcode_boot_requests_percent	A percentage of BootRequest messages
bootp_opcode_boot_replies_percent	A percentage of the BootReply messages
bootp_opcode_invalid_percent	A percentage of neither request nor reply messages
bootp_retransmit_percent	Percentage of retransmissions
bootp_retransmit_secs_avg	Average number of seconds the DHCP clients have been retrying to acquire a lease
bootp_retransmit_longest_trying_client	MAC address of a client who has been trying to get the lease the longest
dhcpv4_roundtrip_dora_milliseconds_avg	Average time in milliseconds to complete a successful 4-way (DORA) exchange
dhcpv4_roundtrip_dora_do_milliseconds_avg	Average time in milliseconds to complete a Discover/Offer exchange during the 4-way (DORA) exchange
dhcpv4_roundtrip_dora_ra_milliseconds_avg	Average time in milliseconds to complete a Request/Ack exchange during the 4-way (DORA) exchange

Many of the metrics listed above (e.g., average or percentages) are computed using the last N packets. The default number of packets is 100 but can be changed to an arbitrary value using the --sampling-window-size command line switch. The lower the value the more dynamic are the metric changes over time. This parameter is not applicable to the full pcap file analysis.

The metrics can be reported over several different channels: CSV write to a file or console, export to Prometheus, Server Sent Events, or the REST API. Consult the User's Manual for details.

License

Endure is licensed under the MIT License.