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Proxy Command

The proxy command starts VIIPER in proxy mode, sitting between a USBIP client and a USBIP server.
VIIPER intercepts and logs all USB traffic passing through, without handling the devices directly.

This is useful for reverse engineering USB protocols and understanding how devices communicate.

USBIP Client  →  VIIPER Proxy  →  USBIP Server (real devices or VIIPER)
                      ↓
              Logs/Captures Traffic

Usage

viiper proxy --upstream=<address> [OPTIONS]

Options

--listen-addr

Proxy listen address (where clients connect).

Default: :3241
Environment Variable: VIIPER_PROXY_ADDR

--upstream

Required. Upstream USBIP server address (where real devices are).

Environment Variable: VIIPER_PROXY_UPSTREAM

--connection-timeout

Connection timeout for proxy operations.

Default: 30s
Environment Variable: VIIPER_PROXY_TIMEOUT

Examples

Basic Proxy

Start proxy between local clients and remote USBIP server:

viiper proxy --upstream=192.168.1.100:3240

Clients connect to localhost:3241, traffic is proxied to 192.168.1.100:3240.

Custom Listen Address

Start proxy on a different port:

viiper proxy --listen-addr=:9000 --upstream=192.168.1.100:3240

Clients connect to localhost:9000, traffic is proxied to 192.168.1.100:3240.

With Raw Packet Logging

Capture all USB traffic for reverse engineering:

viiper proxy --upstream=192.168.1.100:3240 --log.raw-file=usb-capture.log

All USB packets will be logged to usb-capture.log.

With Debug Logging

Enable debug logging to see proxy operations:

viiper proxy --upstream=192.168.1.100:3240 --log.level=debug

Use Cases

Reverse Engineering

Intercept USB traffic between a client and server to understand device protocols:

viiper proxy --upstream=real-server:3240 --log.raw-file=device-capture.log

Traffic Analysis

Monitor USB communication for debugging:

viiper proxy --upstream=real-server:3240 --log.level=trace

Network Inspection

Route USB traffic through VIIPER to inspect and log all operations:

viiper proxy --upstream=real-server:3240 --log.level=debug --log.raw-file=traffic.log

See Also