Replay
Send your own packets over TCP, TLS, STARTTLS, UDP, DTLS and QUIC, in as many tabs as you need.
Replay
Replay lets you build and send packets yourself, the way Burp's Repeater does for HTTP, but for any protocol InterceptSuite supports: TCP, TLS, UDP, DTLS and QUIC, plus STARTTLS upgrades.
Open the Replay tab. Each session is its own tab; click + New Session for another. Sessions, their packets and settings are saved with the project.
Start a session
- Enter the Host or IP and Port.
- Choose the Protocol.
- Optionally set the ALPN (for example
h3for QUIC,h2orhttp/1.1for TLS). - Type or edit the payload and click Send. The session connects on the first send.
From Proxy History
Right-click a packet in Proxy History and choose Send to Replay. The host, port, protocol, ALPN and payload are copied into a new session.
Composing a payload
The payload editor has the same tabs as the Intercept tab:
- Raw: edit as text.
- Hex: edit the bytes in hexadecimal. See Hex Editor.
- Extension tabs: edit a decoded view (for example DNS or HTTP/3). The extension re-encodes your edit into bytes.
Binary payloads are sent exactly as shown. The conversation panel lists every packet sent and received, with direction, size, time and TLS details; select one to inspect it.
Protocols
| Protocol | Notes |
|---|---|
| TCP | Plain connection. Use Upgrade TLS to start TLS on the same connection (STARTTLS) |
| TLS | Handshake with the server using your ALPN |
| UDP | One datagram per send. Empty payloads are allowed |
| DTLS | Datagram TLS |
| QUIC | See below |
STARTTLS
Connect with TCP, exchange the plain-text commands the protocol needs (for example STARTTLS for SMTP), then click Upgrade TLS. Packets after the upgrade are shown as TLS.
QUIC
QUIC carries many streams on one connection, so two extra controls appear next to Send:
| Control | Meaning |
|---|---|
| Stream | New bidirectional stream (default, like a request), New unidirectional stream, or Last stream (keep writing to the previous send's stream) |
| End stream (FIN) | Finish the stream after this send. Most servers answer a request only when it is complete |
The conversation shows the stream each packet used, and marks when the server finishes, resets or stops a stream. If the connection is closed, the reason is shown.
Upstream proxy
Replay uses the active upstream proxy from the Settings tab, just like the main proxy. See Global Settings.
Tips
- Use a separate tab per test so you can compare results side by side.
- Disconnect ends the connection and keeps the tab; the × on a tab closes it.
- A handshake that does not complete within about 10 seconds is reported as failed.