User-space TCP/IP stack
- IPv4 fragmentation and reassembly is supported.
- IPv4 options are not supported and are silently ignored.
- IPv6 fragmentation and reassembly is supported (Fragment extension header, RFC 8200 §4.5).
- Hop-by-Hop Options, Routing and Destination Options extension headers are parsed and skipped.
- AH/ESP and extension headers located inside the fragmentable part are not supported; such packets are rejected.
- NDP is out of scope: the stack sits on a TUN device (layer 3), so there is no link layer to discover.
Use UdpSocket. Supported over IPv4 and IPv6.
Use IcmpSocket or IcmpV6Socket. The user needs to handle the ICMP header themselves and calculate the checksum.
Use TcpListener and TcpStream. Supported over IPv4 and IPv6.
- MSS is negotiated
- Window scaling is negotiated.
- Reassembly of out-of-order segments is supported
- The timeout waiting time is fixed and can be configured
- Selective acknowledgements permitted. (Proactively ACK the need for improvement)
The Linux-only suite under tests/packetdrill drives the userspace stack through
packetdrill's local TUN mode. It covers IPv4 and IPv6 handshake negotiation, data
and ACK behavior, reassembly/SACK, retransmission and fast recovery, zero-window
probing, close/TIME_WAIT paths, and RST/duplicate-SYN handling.
On Ubuntu, run as root because the harness needs TUN, raw-socket, and firewall access:
sudo -E bash scripts/setup_packetdrill.sh --install-deps
sudo -E bash scripts/run_packetdrill.shOn Windows with WSL2 Ubuntu 24.04:
pwsh scripts/run_packetdrill_wsl.ps1The setup script checks out the pinned upstream packetdrill revision into the
user cache. It does not vendor packetdrill into this repository. Per-case verbose
logs are written to target/packetdrill/logs.
Using IpSocket to send and receive packets of other protocols.(Handles all IP upper-layer protocols without requiring the user to consider IP fragmentation.)
Example：Proxy-Windows
Example: Proxy-Linux
