跳转至

使用两张无线网卡桥接 WLAN 网络

文档时效性说明

本文为早期笔记，可能存在版本过时、命令失效、链接失效、最佳实践变化等问题。请以官方最新文档为准。

原英文标题：Bridging WLAN Networks Using 2 Wireless Cards

1. 方法一：brctl（不可用）

wlan0：开启 4addr

1
sudo iw dev wlan0 set 4addr on

wlan1：开启监听模式

1
sudo airmon-ng start wlan1

启动 AP

1
sudo airbase-ng --essid HUST_WIRELESS_TWIN -c 6 wlan1mon

添加桥接

1
2
3
sudo brctl addbr mitm-bridge
sudo brctl addif mitm-bridge at0
sudo brctl addif mitm-bridge wlan0

2. 方法二：hostapd

编辑 hostapd.conf

1
2
3
interface=wlan1
ssid=Wifi_Lab
channel=6

编辑 dnsmasq.conf

1
2
3
4
5
6
interface=wlan1
dhcp-range=10.0.0.10,10.0.0.250,255.255.255.0,12h
dhcp-option=3,10.0.0.1
dhcp-option=6,10.0.0.1
log-queries
log-dhcp

编辑 fakehosts.conf

1
10.0.0.1 baidu.com

启动 DNS 和 DHCP 服务器

1
sudo dnsmasq -C dnsmasq.conf -H fakehosts.conf -d

启动 AP

1
sudo hostapd hostapd.conf

为 AP 分配 IP

1
sudo ifconfig wlan1 10.0.0.1

启用 NAT

1
2
3
4
5
6
7
8
iptables --flush
iptables --table nat --flush
iptables --delete-chain
iptables --table nat --delete-chain
iptables -P FORWARD ACCEPT
iptables --table nat --append POSTROUTING --out-interface wlan0 -j MASQUERADE
iptables --append FORWARD --in-interface wlan0 -j ACCEPT
echo 1 > /proc/sys/net/ipv4/ip_forward

提示：可以将 wlan0 替换为 tun0，以通过 WiFi 共享 VPN 隧道。

3. 故障排查

3.1 热点不稳定

编辑 /etc/NetworkManager/NetworkManager.conf，将 wlan1 加入 unmanaged

1
2
[keyfile]
unmanaged-devices=interface-name:wlan1

然后重启服务

1
sudo systemctl restart NetworkManager

另请参阅：https://wiki.archlinux.org/index.php/software_access_point#NetworkManager_is_interfering

4. 原文（English）

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
---
tags:
  - 网络
  - Linux
---

# 使用两张无线网卡桥接 WLAN 网络


!!! warning "文档时效性说明"
    本文为早期笔记，可能存在版本过时、命令失效、链接失效、最佳实践变化等问题。请以官方最新文档为准。

## Method 1: brctl (Not working)

wlan0: turn on 4addr

```bash
sudo iw dev wlan0 set 4addr on

wlan1: turn on monitor mode

1
sudo airmon-ng start wlan1

fire up the ap

1
sudo airbase-ng --essid HUST_WIRELESS_TWIN -c 6 wlan1mon

add bridge

1
2
3
sudo brctl addbr mitm-bridge
sudo brctl addif mitm-bridge at0
sudo brctl addif mitm-bridge wlan0

Method 2: hostapd

edit hostapd.conf

1
2
3
interface=wlan1
ssid=Wifi_Lab
channel=6

edit dnsmasq.conf

1
2
3
4
5
6
interface=wlan1
dhcp-range=10.0.0.10,10.0.0.250,255.255.255.0,12h
dhcp-option=3,10.0.0.1
dhcp-option=6,10.0.0.1
log-queries
log-dhcp

edit fakehosts.conf

1
10.0.0.1 baidu.com

fire up DNS and DHCP server

1
sudo dnsmasq -C dnsmasq.conf -H fakehosts.conf -d

fire up the access point

1
sudo hostapd hostapd.conf

assign IP to ap

1
sudo ifconfig wlan1 10.0.0.1

enable NAT

1
2
3
4
5
6
7
8
iptables --flush
iptables --table nat --flush
iptables --delete-chain
iptables --table nat --delete-chain
iptables -P FORWARD ACCEPT
iptables --table nat --append POSTROUTING --out-interface wlan0 -j MASQUERADE
iptables --append FORWARD --in-interface wlan0 -j ACCEPT
echo 1 > /proc/sys/net/ipv4/ip_forward

Tips: you may replace wlan0 to tun0 to share VPN tunnel through WiFi.

Trouble Shooting

Hotspot unstable

edit /etc/NetworkManager/NetworkManager.conf, add wlan1 to unmanaged

1
2
[keyfile]
unmanaged-devices=interface-name:wlan1

and restart service

1
sudo systemctl restart NetworkManager

See also: https://wiki.archlinux.org/index.php/software_access_point#NetworkManager_is_interfering ```