Overview:
We are creating a private APN solution for routing traffic from 50–100 SIM cards in our infrastructure with the ability to direct SIM traffic to different internet exit points based on geographical criteria. The project will use the CDA_GREoIPSEC option from the mobile operator.
The freelancer is required to configure the central router/firewall to terminate the GREoIPSEC tunnel and establish policy-based routing to two Debian-based VPS in different geolocations.
Scope of Work
1. Router Configuration
• Deployment and configuration of a dedicated router/firewall to terminate the CDA_GREoIPSEC tunnel from the operator.
• Assignment of appropriate private IP subnets for SIM traffic transmitted through the tunnel.
• Implementation of policy-based routing so that different groups of SIM cards have their own exit tunnel.
2. VPS Exit Configuration (two locations)
• Deployment of two VPS (recommended Debian 12) in different geolocations.
• Configuration of secure tunnels from the central router to each VPS.
• Setting up NAT on the VPS so that outgoing traffic has the public IP address of the VPS.
3. GREoIPSEC Tunnel Verification
• Testing and verification of the tunnel with the operator to ensure stable traffic.
• Verification of encryption and routing functionality.
4. Documentation
• Providing complete configuration documentation, which includes:
• Tunnel configuration parameters from the operator.
• Router configuration.
• VPS tunnel configurations.
• Policy routing tables.
Required Skills
• Experience in networking technologies and routing.
• Experience with GRE tunnels, IPSec, and policy-based routing.
• Experience in administering Linux networks (iptables/nftables, strongSwan, FRR, WireGuard).
• Experience with firewalls/routers (VyOS, pfSense, Fortinet).
Deliverables
• A working CDA_GREoIPSEC tunnel on the central router.
• Two VPS exits with complete tunnel and NAT configuration.
• Configuration of policy-based routing by SIM subnets.
• Complete documentation and solution diagram.
Budget
• Fixed price — please specify the final cost.
Additional Notes
• The operator will provide the private APN parameters and the CDA_GREoIPSEC tunnel.
• We provide the router and VPS hardware.
