> ## Documentation Index
> Fetch the complete documentation index at: https://docs.tracenav.net/llms.txt
> Use this file to discover all available pages before exploring further.

# NTRIP 1.0 Overview

> Understand how TraceNav streams RTCM corrections using standard NTRIP workflows

NTRIP (Networked Transport of RTCM via Internet Protocol) is the industry standard for streaming GNSS correction data. It wraps binary RTCM frames in a lightweight HTTP/1.0-style exchange so that rovers can connect through common firewalls and proxies without custom networking.

## End-to-end topology

```
Base station → NTRIP Server → TraceNav Caster → NTRIP Client (rover)
```

The caster behaves like a router: it accepts upstream uploads from bases or regional aggregators and forwards the selected stream to each connected rover.

## Client connection flow

<Steps>
  <Step title="(Optional) Fetch source table">
    ```http theme={null}
    GET / HTTP/1.0\r
    User-Agent: NTRIP TraceClient/1.0\r
    Authorization: Basic <base64(user:password)>\r
    \r
    ```

    TraceRouter replies with the standard NTRIP source table (`STR;`, `CAS;`, `NET;` entries). Many modern rovers skip this step and connect directly if the mountpoint is known.
  </Step>

  <Step title="Connect to /tracenav">
    ```http theme={null}
    GET /tracenav HTTP/1.0\r
    User-Agent: NTRIP TraceClient/1.0\r
    Authorization: Basic <base64(user:password)>\r
    \r
    ```
  </Step>

  <Step title="Caster response">
    ```http theme={null}
    ICY 200 OK\r
    <binary RTCM stream>
    ```
  </Step>
</Steps>

If a rover requests an invalid mountpoint, TraceRouter also returns the source table so the client can renegotiate.

## Base station uploads

TraceRouter exposes two mountpoints:

* `/tracenav` — rover and client connections (HTTP `GET`)
* `/serve` — base stations uploading correction data (HTTP `SOURCE`)

Reference stations authenticated to TraceNav push data with:

```http theme={null}
SOURCE /serve HTTP/1.0\r
Source-Agent: NTRIP TraceServer/1.0\r
Authorization: Basic <base64(user:password)>\r
\r
<binary RTCM stream>
```

Credentials uniquely identify the base device. TraceRouter maps the upload to the correct project automatically—no manual mountpoint management is required.

## Authentication and security

* **Mechanism**: HTTP Basic Auth (`username:password` Base64 encoded)
* **Transport**: Plain TCP (no TLS in the NTRIP 1.0 spec)
* **TraceNav recommendation**: Run clients inside a TLS tunnel, VPN, or cellular APN to secure credentials and data in transit.

## RTCM frame basics

Each RTCM 3.x packet contains:

1. Sync header `0xD3`
2. 10-bit payload length
3. Message payload (binary, message type + data)
4. CRC-24Q checksum

TraceNav forwards frames byte-for-byte—no transcoding or re-encoding—so any NTRIP-compliant rover can ingest the data directly.

## Related reading

* <a href="/products/tracerouter">TraceRouter service</a> – how TraceNav orchestrates NTRIP sessions
* <a href="/protocols/rtcm-message-map">RTCM message map</a> – decode the structures inside each RTCM frame