When implementing VPN solutions, one common pitfall is IP address conflicts between the corporate network and remote clients' home networks. Many SOHO routers default to using 192.168.0.0/24 or 192.168.1.0/24 subnet ranges, which can create routing conflicts when remote employees connect via VPN.

To avoid these conflicts, consider these alternative private IP ranges:

• 10.0.0.0/8 (10.0.0.0 to 10.255.255.255)
• 172.16.0.0/12 (172.16.0.0 to 172.31.255.255)
• 192.168.0.0/16 (but choose less common subnets like 192.168.77.0/24)

Here's a sample configuration for OpenVPN server that uses a less common subnet:

server 10.8.77.0 255.255.255.0
push "route 10.8.77.0 255.255.255.0"
push "dhcp-option DNS 10.8.77.1"
push "redirect-gateway def1"

For larger organizations, implement network segmentation:

# Firewall rules example (iptables)
iptables -A FORWARD -i tun0 -o eth0 -s 10.8.77.0/24 -d 10.0.0.0/8 -j ACCEPT
iptables -A FORWARD -i eth0 -o tun0 -s 10.0.0.0/8 -d 10.8.77.0/24 -j ACCEPT

Educate users about checking their home network configurations. Provide documentation suggesting they:

1. Change home router's default IP range
2. Use alternative private ranges (like 192.168.77.0/24)
3. Configure split tunneling when appropriate

For maximum compatibility, implement NAT for VPN clients:

# NAT configuration example
iptables -t nat -A POSTROUTING -s 10.8.77.0/24 -o eth0 -j MASQUERADE
iptables -A FORWARD -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
iptables -A FORWARD -i tun0 -o eth0 -j ACCEPT

When remote users connect via VPN, their local network configuration can clash with your corporate network if both use the same private IP range (like 192.168.0.0/24). This creates routing conflicts where devices can't determine which 192.168.0.1 gateway to use - their home router or your corporate firewall.

Here are three proven approaches to avoid these conflicts:

// Sample network configuration snippets
// Option 1: Use less common RFC 1918 ranges
corporate_network = "10.45.0.0/16"
vpn_pool = "10.45.254.0/24"

// Option 2: Medium-sized network alternative
corporate_network = "172.20.0.0/16" 
vpn_pool = "172.21.0.0/24"

// Option 3: Large enterprise solution 
corporate_network = "10.100.0.0/14" // 10.100.0.0 - 10.103.255.255
department_subnets = ["10.100.1.0/24", "10.100.2.0/24"] 
vpn_pool = "10.104.0.0/22"

When redesigning your network addressing scheme:

• Document all existing static IP assignments before migration
• Use DHCP reservations rather than static IPs where possible
• Consider implementing split-tunneling for VPN clients
• Test connectivity for all critical services after changes

Here's how to modify pfSense firewall settings to implement a conflict-free VPN setup:

# pfSense OpenVPN server configuration
server {
  local 10.45.254.1;
  push "route 10.45.0.0 255.255.0.0";
  server 10.45.254.0 255.255.255.0;
  topology subnet;
  client-to-client;
}