Leveraging Reftek’s RTP for Reliable Seismic Data Transmission Through Firewalls
Executive Summary
Remote seismic stations often face communication challenges due to restrictive firewalls and dynamic IP environments. The Ref Tek Protocol (RTP) offers a lightweight, firewall-tolerant, IP-agnostic SEEDLink alternative for streaming seismic data from Reftek instruments to central servers. Its ability to operate through outbound-only UDP connections makes it highly compatible with constrained networks, including Starlink, which provides high-speed internet with non-static, carrier-grade NAT IPs. RTP thus enables secure, scalable data telemetry without requiring static IPs, VPNs, or complex firewall rules.
Introduction
Seismic networks require uninterrupted communication between field instruments and central processing systems. However, many modern connectivity solutions, such as satellite links and 4G/LTE/5G modems, introduce complications, including dynamic IP addressing and firewall restrictions.
RTP solves both issues by inverting the traditional client-server model. Instead of polling devices, the field digitizers initiate outbound UDP connections to the central RTPD server, allowing seamless operation even behind carrier NATs or firewalls.
Overview of RTP
RTP is a protocol for transmitting seismic data over persistent UDP connections initiated by Reftek field digitizers. It supports:
- Multi-device handling via concurrent sessions
- Lightweight, low-bandwidth binary protocol
- Daemonized architecture, suitable for long-term deployment
- Integration with Reftek digitizers
- Supports PASSCAL (“REFTEK”), MRF, and MiniSEED data formats
Firewall and Network Constraints in Seismic Deployments
Constraint
Inbound port blocks
NAT obscures the device IP
Dynamic IPs (e.g., 4G, Starlink)
Institutional firewalls
Impact on Telemetry
Prevent server-initiated data pulls
Complicates direct addressing
Break IP whitelisting, DNS resolution is unreliable
Inhibit inbound or tunneled traffic, complicate the setup
How RTP Bypasses These Challenges
Challenge
Inbound traffic blocked
NAT traversal
Dynamic IPs
Carrier-grade NAT
RTP Mechanism
Field devices initiate outbound connections to the RTP server
Connection initiated from the inside; NAT is transparently handled
No fixed IP needed at the field site
Still supports connectivity without a public IP address
Both Reftek RTP and SeedLink are widely used in seismic data telemetry, but they differ significantly in architecture, protocol behavior, and network compatibility. Below is a detailed comparison with a focus on deployment in firewall-constrained and dynamic-IP environments.
Overview of RTP and Seedlink Protocols
Feature
Protocol Type
Data Direction
Devices Supported
RTP
Proprietary binary protocol over UDP
Push (field → server)
Reftek 130/180 series
SeedLink
ASCII-based control + MiniSEED over TCP
Pull (server → field station or relay node)
Broad: Reftek. Nanometrics, Kinemetrics, Guralp, etc.
Network & Firewall Behavior
Capability
Connection Initiation
Firewall/NAT Traversal
Static IP Requirement (Field)
Port Forwarding Needed (Field)
Dynamic IP Tolerance
RTP
Client (digitizer) initiates outbound UDP connection to central server
Works behind NAT/CGNAT (e.g. Starlink)
Not required
No
Fully supported
SeedLink
Client (central server) initiates a connection to the digitizer or relay
Requires static IP or port forwarding
Typically required
Usually required
Problematic unless paired with dynamic DNS
Use with Starlink or Cellular Networks
Aspect
Starlink-Compatible
Cellular Network Support
DNS or IP Management Needed
RTP
Yes (CGNAT-friendly)
Easily works with 4G/5G modems
No
SeedLink
Not without VPNs or IP tunneling
Requires workaround, static IPs, or VPN
Often required
Example Use Case: Remote Seismic Station with Starlink Uplink
A national seismic agency deploys 30 seismic stations in remote areas with no cellular coverage. Each station is equipped with a Reftek Wrangler digitizer and a Starlink terminal.
Overview of Starlink Connectivity Constraints
Starlink offers broadband internet with global coverage, making it ideal for remote seismic sites. However, it introduces specific networking constraints:
- Non-static, dynamic IPs assigned via DHCP
- Carrier-Grade NAT (CGNAT) prevents direct inbound connections
- No native support for port forwarding
- Latency and jitter are typical of satellite systems
These factors make traditional Seedlink protocol telemetry approaches more complicated.
How RTP Enables Seamless Operation Over Starlink
Starlink Constraint
No static IP / CGNAT
No port forwarding available
High latency
Dynamic IPs on reconnect
RTP Benefit
Outbound-only model bypasses the need for a public or static IP
No inbound ports required; works without router configuration
An efficient, persistent TCP connection minimizes retransmits
Server accepts connections from any IP; no client IP tracking
Operational Advantages in the Field
- "Plug-and-play" with Starlink terminals: Configure digitizer with server IP, and RTP handles the rest.
- No need for IP management or DNS hacks at the field site.
- Reliable long-term operation: Devices reconnect automatically after power loss or dynamic IP change.
- Ideal for remote regions with no cellular coverage but open sky access.
- Without RTP: VPN or dynamic DNS solutions are required — prone to failure with CGNAT and frequent IP changes.
- With RTP: Each digitizer connects out to the central server via Starlink. No IP tracking, port forwarding, or firewall exceptions required.
Conclusion
RTP is uniquely suited to modern seismic deployments, particularly those utilizing Starlink or other dynamic-IP connectivity solutions. Its ability to bypass firewalls, handle NAT, and operate independently of IP persistence makes it a powerful tool for reliable, scalable seismic data telemetry. For institutions looking to modernize their field infrastructure while reducing IT overhead, RTP offers a robust and future-ready solution.
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