Network Configuration

Detailed guide for configuring Espilon's WiFi and GPRS connectivity.

WiFi Configuration

Basic Settings

Configure via idf.py menuconfig:

Espilon Bot Configuration → Network → WiFi Settings

Setting	Description	Example
SSID	Network name	"MyWiFi"
Password	WPA/WPA2 key	"MyPassword123"

Supported Security

• WPA-PSK
• WPA2-PSK
• WPA3-SAE (ESP-IDF v5.0+)
• Open (no password)

Not supported: WPA-Enterprise, captive portals

WiFi Range

Typical range: - Indoor: 50-100m - Outdoor: 300m+ - With external antenna: 500m+

GPRS Configuration

Requirements

• LilyGO T-Call board
• Active SIM card (2G data plan)
• GSM antenna connected
• PIN code disabled

APN Configuration

Configure via idf.py menuconfig:

Espilon Bot Configuration → Network → GPRS Settings → APN

Common APNs:

Carrier	Country	APN
SFR	France	sl2sfr
Orange	France	orange.fr
Bouygues	France	mmsbouygtel.com
Free Mobile	France	free
AT&T	USA	phone
T-Mobile	USA	fast.t-mobile.com
Verizon	USA	vzwinternet
Vodafone	UK	pp.vodafone.co.uk

Network Registration

After power-on, SIM800 will:

1. Initialize modem (~5s)
2. Search for networks (~10s)
3. Register on carrier (~15s)
4. Activate GPRS (~5s)

Total time: ~30-40 seconds

Public IP Requirement

GPRS mode requires public IP for C2 server:

• ✅ Public static IP
• ✅ Dynamic DNS service
• ✅ VPN with port forwarding
• ❌ Local IP (192.168.x.x)
• ❌ Carrier-grade NAT only

Server Configuration

C2 Server Settings

Espilon Bot Configuration → Server
├─ Server IP: IP address of C2
└─ Server Port: 2626 (default)

WiFi Mode: Use local or public IP GPRS Mode: Must use public IP

Port Selection

Default: 2626

Alternative ports: - Avoid: 80, 443, 22, 21 (common filtered ports) - Safe: 2626, 8080, 4444, 31337

Firewall Configuration

Ensure C2 server allows incoming connections:

# Linux (ufw)
sudo ufw allow 2626/tcp

# Linux (iptables)
sudo iptables -A INPUT -p tcp --dport 2626 -j ACCEPT

# Check if listening
netstat -tln | grep 2626

Connection Process

WiFi Mode

1. ESP32 starts WiFi
2. Scans for SSID
3. Connects with password
4. Obtains IP via DHCP
5. Connects to C2 server (TCP)
6. Performs ChaCha20 handshake

GPRS Mode

1. ESP32 powers SIM800
2. SIM800 registers on network
3. Activates GPRS connection
4. Establishes TCP connection to C2
5. Performs ChaCha20 handshake

Troubleshooting

WiFi Won't Connect

Problem: Can't find or connect to network

Checks: - SSID correct (case-sensitive) - Password correct - 2.4GHz network (ESP32 doesn't support 5GHz) - Router not MAC-filtered

GPRS Registration Failed

Problem: Stuck at "Registering on network"

Checks: - SIM card inserted correctly - Data plan active - PIN code disabled - Antenna connected - 2G coverage available

C2 Connection Timeout

Problem: Can't reach C2 server

Checks: - Server IP correct - Server running and listening - Firewall allows port 2626 - Network connectivity (ping test)

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