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Router Internet Sharing Blocked by Provider: How to Fix

Learn how to bypass provider internet blocking in dormitories by setting up MAC address cloning in OpenWRT routers and alternative methods for sharing internet.

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How to set up internet sharing through a router when the provider blocks connections from other devices?

Problem:

  • In the dormitory, internet is only provided for one MAC address
  • Internet sharing through the laptop’s hotspot works
  • Sharing through the router doesn’t work

Attempts at solution:

  • A Xiaomi 4A (R4AC) router with OpenWRT firmware is installed
  • The MAC address of the main computer has been cloned
  • Attempts to copy other information: hostname, vendor class, client ID
  • The router’s TTL matches the computer’s TTL

Symptoms:

  • The router itself gets internet (ping works, opkg downloads packages)
  • When connecting via SSH, internet access is confirmed
  • The same router with the same settings works in another dormitory

Question: How to solve the problem of the provider blocking internet sharing and bypass this restriction?

NeuroAgent

To solve the problem of internet provider blocking when sharing through a router in a dormitory, you need to configure MAC address cloning of your main computer in OpenWRT through the LuCI interface in the “Network → Interfaces → WAN → Advanced → Override MAC address” section or through the command line for more precise configuration, as providers often use not only MAC addresses but also other parameters to identify devices.

Table of Contents

Understanding MAC Filtering Problem

Providers in dormitories often use MAC filtering to control network access, allowing only devices with pre-registered MAC addresses to connect. This measure allows them to manage the number of devices used simultaneously and prevent unauthorized access.

The problem you’re encountering occurs because the router has its own hardware MAC address, which differs from the MAC address of your main computer. Even when cloning the MAC address, the provider may use additional identification mechanisms:

The problem may not only be with the MAC address but also with other parameters such as hostname, vendor class identifier, DHCP client ID, or even behavioral characteristics of the connection.

As specialists from the OpenWRT community point out, some providers may track DHCP request sequences or use equipment signatures to determine that a different device is connected than what was initially registered.

Setting Up MAC Address Cloning in OpenWRT

Setup Through LuCI Web Interface

The easiest way to clone a MAC address in OpenWRT is to use the LuCI web interface:

  1. Go to the router’s web interface (usually at address 192.168.1.1)
  2. Navigate to: Network → Interfaces → WAN → Advanced
  3. Find the option: “Override MAC address”
  4. Enter your main computer’s MAC address in the format XX:XX:XX:XX:XX:XX
  5. Save the settings and restart the router

Important: Some routers have multiple network interfaces. Make sure you’re configuring the correct interface - usually this is the WAN port (eth0 or eth1 depending on the model).

Setup Through Command Line

For more precise control and to troubleshoot MAC address cloning issues, you can use the command line:

bash
# Determine the WAN interface name
ubus list network.interface

# Stop the interface
ifconfig eth1 down

# Set the new MAC address
ifconfig eth1 hw ether AA:BB:CC:DD:EE:FF

# Start the interface
ifconfig eth1 up

# Check the settings
ifconfig eth1

Where eth1 is your WAN interface and AA:BB:CC:DD:EE:FF is your computer’s MAC address.

Alternative Methods to Bypass Restrictions

Using Bridge Mode

If MAC address cloning doesn’t help, you can try configuring the router in bridge mode:

  1. Disable the DHCP server on the OpenWRT router
  2. Disable the WAN port
  3. Connect the provider’s cable to the LAN port of the router
  4. Configure the main router (the one the provider allows) to manage DHCP

In this mode, the OpenWRT router will work as just an access point, and the main router will communicate with the provider, allowing you to bypass MAC filtering.

Using VLAN Tagging

Some providers use VLAN tagging for network segmentation. OpenWRT supports VLAN configuration:

bash
# Add a VLAN interface
vconfig add eth1 100

# Configure the IP address
ifconfig eth1.100 192.168.1.100 netmask 255.255.255.0

# Add the route
ip route add default via 192.168.1.1

Configuring PPPoE Connection

If your provider uses PPPoE authentication, configure the appropriate connection:

  1. In LuCI: Network → Interfaces → Add interface
  2. Select type: PPPoE
  3. Enter your internet account username and password
  4. In the “Advanced” section, you can specify the MAC address

Advanced Settings for Complete Bypass

Cloning DHCP Client ID

Providers may use the DHCP client identifier to identify devices. In OpenWRT, this can be configured:

bash
# Edit the DHCP configuration
uci set network.wan.dhcp_clientid='client-identifier AA:BB:CC:DD:EE:FF'
uci commit network
/etc/init.d/network restart

Modifying TTL Values

If the provider tracks TTL (Time To Live) values, it can be configured to match the computer:

bash
# Set TTL for outgoing packets
iptables -t mangle -A POSTROUTING -o eth1 -j TTL --ttl-set 64

Using OpenVPN

To completely bypass restrictions, you can set up an OpenVPN tunnel:

  1. Install OpenVPN on the router:
bash
opkg update
opkg install openvpn
  1. Configure the OpenVPN client to connect to an external server
  2. Share internet through VPN

This allows you to bypass any local provider restrictions, as all traffic is encrypted and goes through an external server.

Testing and Troubleshooting

Checking MAC Address

Make sure the MAC address has been successfully changed:

bash
ifconfig eth1 | grep ether

Analyzing DHCP Requests

Analyze DHCP requests to identify the problem:

bash
tcpdump -i eth1 -n port 67 or port 68

Checking Error Logs

Check OpenWRT logs for errors:

bash
logread -f

Testing in Different Conditions

Since you mentioned that the router works in a different dormitory, conduct a comparative analysis:

  1. Compare DHCP settings in both locations
  2. Check if the provider uses additional authentication methods
  3. Determine which specific network parameters are being blocked in the current dormitory

Conclusion and Recommendations

  1. Start with basic MAC address cloning through the LuCI interface, as this solves the problem in most cases
  2. Use the command line for more precise configuration and troubleshooting
  3. Try bridge mode if MAC cloning doesn’t help
  4. Configure PPPoE connection if the provider uses such authentication
  5. Use VLAN tagging for networks with segmentation
  6. Consider OpenVPN as a reliable way to bypass any restrictions

If none of these methods work, your provider may be using more complex access control methods, such as network traffic analysis or deep equipment inspection. In this case, you may need to consult with the dormitory system administrator or consider alternative internet options.

Sources

  1. Clone mac question - Installing and Using OpenWrt - OpenWrt Forum
  2. How to clone MAC in OpenWRT? - Installing and Using OpenWrt - OpenWrt Forum
  3. Fix MAC Address Clone in OpenWRT - Pearls in Life
  4. MAC Address Spoofing with OpenWRT
  5. Cloning a MAC address to bypass a captive portal - Fedora Magazine
  6. Change Mac address for PPPOE - Network and Wireless Configuration - OpenWrt Forum
  7. How to bypass restrictive mac address filtering on home network - Information Security Stack Exchange
  8. LEDE/OpenWRT — Restricting Network Access Based on MAC | by CT WiFi | LEDE/OpenWrt & IoT | Medium
How to check if the provider is using MAC filtering instead of other blocking methods?How to set up bridge mode on an OpenWRT router to bypass provider restrictions?What to do if MAC address cloning didn't help solve the internet access problem?How to configure VLAN tagging in OpenWRT for working with provider networks that use segmentation?How to use OpenVPN to completely bypass provider restrictions in a dormitory?How to determine which specific network parameter (besides MAC address) is blocking the router connection?
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