bootpd

A small, self-contained DHCP/BOOTP + TFTP server for network booting, built for developing and testing (legacy) PXE boot loaders.

Point it at a directory, list the machines you want to boot by MAC address, and it answers their DHCP requests with an address and a boot file, then serves that file over TFTP. No address pools, no leases database, no system service to configure: one executable and one .ini file.

 PXE client                                   bootpd
 ──────────                                   ──────
 DHCPDISCOVER  ─────────────────────────────▶  known MAC? ──▶ DHCPOFFER  (address, server, boot file)
 DHCPREQUEST   ─────────────────────────────▶             ──▶ DHCPACK
 TFTP RRQ "pxelinux.0" (blksize, tsize) ────▶  new session ─▶ OACK, DATA 1..n

• DHCP and plain BOOTP: answers DISCOVER with OFFER, REQUEST with ACK and BOOTP requests with BOOTREPLY. It ignores unknown machines, so it can share a network with other devices.
• Per-machine configuration: address, subnet mask, router, boot file, host and domain name, lease times.
• TFTP read server (RFC 1350) with option negotiation: blksize, timeout and tsize (RFC 2347, 2348, 2349). Concurrent transfers, retransmission on timeout, duplicate-ACK tolerance.
• Safe by default: nothing outside the TFTP root is ever served. .., absolute paths and escaping symlinks are all refused. Uploads are refused.
• Single threaded, built on C++20 coroutines. See docs/architecture.md.
• Runs on Windows and Linux.

1. Give the network adapter facing the machines to boot a static address, for example 10.0.0.1/8.

2. Put the boot file (the NBP, e.g. pxelinux.0 or your own loader) in a directory.

3. Write a config.ini:

   v4_bind_address = 10.0.0.1
   tftp_base_dir   = ./tftp
   
   [00-1c-7e-35-ed-20]           ; MAC address of the machine to boot
   boot_file_name    = pxelinux.0
   v4_your_address   = 10.0.0.2  ; address given to that machine
   v4_server_address = 10.0.0.1  ; this computer
   v4_subnet_mask    = 255.0.0.0

4. Run it (ports 67 and 69 need administrator/root rights on Linux, see Platform notes):

   bootpd -C config.ini

5. Power on the client and choose network boot. Press Ctrl+C to stop the server.

The full list of settings is in the configuration reference. There is a commented example in example/config.ini.

bootpd [options]

  -C <file>         Configuration file (default: config.ini)
  -O "<key=value>"  Override a global configuration value, may be repeated
  -v, --verbose     Debug log output (-vv for trace output)
  -q, --quiet       Only log warnings and errors
  -h, --help        Show help and exit
  -V, --version     Show the version and exit

-O is handy for one-off changes without editing the file:

bootpd -C config.ini -O "tftp_base_dir = ./other-build" -O "dhcp_enabled = false"

A typical session log:

2026-09-30 19:27:05 INFO    DHCP server listening on '10.0.0.1:67', 1 client(s) configured.
2026-09-30 19:27:05 INFO    TFTP server listening on '10.0.0.1:69', serving files from 'C:\pxe\tftp'.
2026-09-30 19:27:09 INFO    Responding to DHCPDISCOVER from '00-1c-7e-35-ed-20' (xid 0x8f3c2a11) with DHCPOFFER, offering 10.0.0.2.
2026-09-30 19:27:10 INFO    Responding to DHCPREQUEST from '00-1c-7e-35-ed-20' (xid 0x8f3c2a11) with DHCPACK, offering 10.0.0.2.
2026-09-30 19:27:10 INFO    From '10.0.0.2:2070' received : RRQ(file="pxelinux.0", mode="octet", tsize="0")
2026-09-30 19:27:10 INFO    Sending 'pxelinux.0' to '10.0.0.2:2070' (42376 bytes, blksize = 512, timeout = 1s) ...
2026-09-30 19:27:10 INFO    Finished sending 'pxelinux.0' to '10.0.0.2:2070' in 0.09s.

You need a C++20 compiler (MSVC 2022, GCC 13+ or Clang 17+), CMake 3.20+ and Conan 2 for the test dependencies (GoogleTest).

pip install conan
conan profile detect

# Build, run the tests and create the package in one go:
conan build . --build=missing -s compiler.cppstd=20

Or step by step, using the CMake presets Conan generates:

conan install . --build=missing -s compiler.cppstd=20
cmake --preset conan-release          # Windows / Visual Studio: conan-default
cmake --build --preset conan-release
ctest --preset conan-release --output-on-failure

build.sh (Linux) and build.bat (Windows) do the same and install into ./workspace. To build without Conan and without the tests, plain CMake is enough:

cmake -S . -B build -DCMAKE_BUILD_TYPE=Release
cmake --build build

Conan options:

For example conan build . -s compiler.cppstd=20 -o "&:with_tests=False".

The tests/ directory holds the GoogleTest suite. It covers:

• unit tests for the configuration parser, argument parser, serializer and address handling;
• DHCP option/packet encoding, including malformed and hostile input;
• the DHCP reply logic (offers, acks, BOOTP, relays, unknown clients);
• TFTP packets, block reading, option negotiation and path sanitizing;
• the coroutine runtime (tasks, timers, cancellation);
• end-to-end tests that run the real DHCP and TFTP servers on loopback against small in-process clients: downloads, option negotiation, retransmission, duplicate ACKs, concurrent transfers and error cases.

Run them with ctest (see above) or directly with build/Release/tests/bootpd_tests. Set BOOTPD_TEST_LOG=1 to see the server log while they run.

Windows: when Windows asks, allow bootpd.exe through the firewall (UDP 67 and 69). Binding v4_bind_address to the adapter's address is enough to receive broadcasts on that adapter.

Linux:

• Ports below 1024 need root, or grant the capability once: sudo setcap cap_net_bind_service=+ep ./bootpd.
• Linux doesn't deliver broadcast packets (like DHCPDISCOVER) to a socket bound to a specific unicast address. Use v4_bind_address = 0.0.0.0 on Linux, and preferably a machine where the boot network is the only network, or the one with the default route.
• Stop other DHCP servers on the same interface (dnsmasq, libvirt's default network, ...), or set dhcp_enabled = false and use theirs.

• IPv4 only. No DHCPv6 or UEFI HTTP boot.
• Static assignments only: every client needs its own section. There is no address pool.
• TFTP is read-only, and netascii transfers are sent verbatim, like most network boot TFTP servers do.
• No proxyDHCP (port 4011) mode.

bootpd/         the servers: DHCP/TFTP packets, DHCP server, TFTP server and sessions, main()
common/         support library: coroutine runtime, sockets, config parser, logger, ...
tests/          GoogleTest suite
docs/           configuration reference and architecture notes
example/        example configuration and Windows launcher
conanfile.py    Conan recipe (dependencies, build, test)

MIT, see LICENSE.