Linux-router

Set Linux as router in one command. Able to provide Internet, or create WiFi hotspot. Support transparent proxy (redsocks). Also useful for routing VM/containers.

It wraps iptables, dnsmasq etc. stuff. Use in one command, restore in one command or by control-c (or even by closing terminal window).

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Features

Basic features:

Create a NATed sub-network
Provide Internet
DHCP server (and RA)
- Specify what DNS the DHCP server assigns to clients
DNS server
- Specify upstream DNS (kind of a plain DNS proxy)
IPv6 (behind NATed LAN, like IPv4)
Creating WiFi hotspot:
- Channel selecting
- Choose encryptions: WPA2/WPA, WPA2, WPA, No encryption
- Create AP on the same interface you are getting Internet (usually require same channel)
Transparent proxy (redsocks)
Transparent DNS proxy (hijack port 53 packets)
Detect NetworkManager and make sure it won't interfere (handle interface (un)managed status)
You can run many instances, to create many different networks. Has instances managing feature.

For many other features, see below CLI usage

Useful in these situations

Internet----(eth0/wlan0)-Linux-(wlanX)AP
                                       |--client
                                       |--client

                                    Internet
WiFi AP(no DHCP)                        |
    |----(wlan1)-Linux-(eth0/wlan0)------
    |           (DHCP)
    |--client
    |--client

                                    Internet
 Switch                                 |
    |---(eth1)-Linux-(eth0/wlan0)--------
    |--client
    |--client

Internet----(eth0/wlan0)-Linux-(eth1)------Another PC

Internet----(eth0/wlan0)-Linux-(virtual interface)-----VM/container

Install

1-file-script. Release on Linux-router repo on Github. Download and run the bash script (meet the dependencies).

I'm currently not packaging for any distro. If you do, open a PR and add the link (can be with a version badge) to list here:

Linux distro
Any	download 1-file-script and run

Dependencies

bash
procps or procps-ng
iproute2
dnsmasq
iptables (or nftables with iptables-nft translation linked)
WiFi hotspot dependencies
- hostapd
- iw
- iwconfig (you only need this if 'iw' can not recognize your adapter)
- haveged (optional)

Usage

Provide Internet to an interface

sudo lnxrouter -i eth1

no matter which interface (other than eth1) you're getting Internet from.

Create WiFi hotspot

sudo lnxrouter --ap wlan0 MyAccessPoint -p MyPassPhrase

no matter which interface you're getting Internet from (even from wlan0). Will create virtual Interface x0wlan0 for hotspot.

Provide an interface's Internet to another interface

Clients access Internet through only isp5

sudo lnxrouter -i eth1 -o isp5  --no-dns  --dhcp-dns 1.1.1.1  -6 --dhcp-dns6 [2606:4700:4700::1111]

In this case of usage, it's recommended to:

Stop serving local DNS

Tell clients which DNS to use ISP5's DNS. (Or, a safe public DNS, like above example)

Also, read Notice 1

Create LAN without providing Internet

sudo lnxrouter -n -i eth1
sudo lnxrouter -n --ap wlan0 MyAccessPoint -p MyPassPhrase

Read Notice 1

Internet for LXC

Create a bridge

sudo brctl addbr lxcbr5

In LXC container config

lxc.network.type = veth
lxc.network.flags = up
lxc.network.link = lxcbr5
lxc.network.hwaddr = xx:xx:xx:xx:xx:xx

sudo lnxrouter -i lxcbr5

Transparent proxy

All clients' Internet traffic go through, for example, Tor (notice this example is NOT an anonymity use)

sudo lnxrouter -i eth1 --tp 9040 --dns 9053 -g 192.168.55.1 -6 --p6 fd00:5:6:7::

In torrc

TransPort 192.168.55.1:9040 
DNSPort 192.168.55.1:9053
TransPort [fd00:5:6:7::1]:9040 
DNSPort [fd00:5:6:7::1]:9053

Warn: Tor's anonymity relies on a purpose-made browser. Using Tor like this (sharing Tor's network to LAN clients) will NOT ensure anonymity.

Although we use Tor as example here, Linux-router does NOT ensure nor is NOT aiming at anonymity.

Clients-in-sandbox network

To not give our infomation to clients. Clients can still access Internet.

sudo lnxrouter -i eth1 \
    --tp 9040 --dns 9053 \
    --random-mac \
    --ban-priv \
    --catch-dns --log-dns   # optional

Linux-router comes with no warranty. Use on your own risk

Use as transparent proxy for LXD

Create a bridge

sudo brctl addbr lxdbr5

Create and add a new LXD profile overriding container's eth0

lxc profile create profile5
lxc profile edit profile5

### profile content ###
config: {}
description: ""
devices:
  eth0:
    name: eth0
    nictype: bridged
    parent: lxdbr5
    type: nic
name: profile5

lxc profile add <container> profile5

sudo lnxrouter -i lxdbr5 --tp 9040 --dns 9053

To remove that new profile from container

lxc profile remove <container> profile5

To not use profile

Add new eth0 to container overriding default eth0

lxc config device add <container> eth0 nic name=eth0 nictype=bridged parent=lxdbr5

To remove the customized eth0 to restore default eth0

lxc config device remove <container> eth0

Use as transparent proxy for VirtualBox

In VirtualBox's global settings, create a host-only network vboxnet5 with DHCP disabled.

sudo lnxrouter -i vboxnet5 --tp 9040 --dns 9053

Use as transparent proxy for firejail

Create a bridge

sudo brctl addbr firejail5

sudo lnxrouter -i firejail5 -g 192.168.55.1 --tp 9040 --dns 9053 
firejail --net=firejail5 --dns=192.168.55.1 --blacklist=/var/run/nscd

Firejail's /etc/resolv.conf doesn't obtain DNS from DHCP, so we need to assign.

nscd is domain name cache service, which shouldn't be accessed from in jail here.

CLI usage and other features

Usage: lnxrouter <options>

Options:
    -h, --help              Show this help
    --version               Print version number

    -i <interface>          Interface to make NATed sub-network,
                            and to provide Internet to
                            (To create WiFi hotspot use '--ap' instead)
    -o <interface>          Specify an inteface to provide Internet from.
                            (See Notice 1)
                            (Note using this with default DNS option may leak
                            queries to other interfaces)
    -n                      Do not provide Internet (See Notice 1)
    --ban-priv              Disallow clients to access my private network
    
    -g <ip>                 This host's IPv4 address in subnet (mask is /24)
                            (example: '192.168.5.1' or '5' shortly)
    -6                      Enable IPv6 (NAT)
    --no4                   Disable IPv4 Internet (not forwarding IPv4)
                            (See Notice 1). Usually used with '-6'
                            
    --p6 <prefix>           Set IPv6 LAN address prefix (length 64) 
                            (example: 'fd00:0:0:5::' or '5' shortly) 
                            Using this enables '-6'
                            
    --dns <ip>|<port>|<ip:port>
                            DNS server's upstream DNS.
                            Use ',' to seperate multiple servers
                            (default: use /etc/resolve.conf)
                            (Note IPv6 addresses need '[]' around)
    --no-dns                Do not serve DNS
    --no-dnsmasq            Disable dnsmasq server (DHCP, DNS, RA)
    --catch-dns             Transparent DNS proxy, redirect packets(TCP/UDP) 
                            whose destination port is 53 to this host
    --log-dns               Show DNS query log (dnsmasq)
    --dhcp-dns <IP1[,IP2]>|no
                            Set IPv4 DNS offered by DHCP (default: this host).
    --dhcp-dns6 <IP1[,IP2]>|no
                            Set IPv6 DNS offered by DHCP (RA) 
                            (default: this host)
                            (Note IPv6 addresses need '[]' around)
                            Using both above two will enable '--no-dns' 
    --hostname <name>       DNS server associate this name with this host.
                            Use '-' to read name from /etc/hostname
    -d                      DNS server will take into account /etc/hosts
    -e <hosts_file>         DNS server will take into account additional 
                            hosts file
    --dns-nocache           DNS server no cache
    
    --mac <MAC>             Set MAC address
    --random-mac            Use random MAC address
 
    --tp <port>             Transparent proxy,
                            redirect non-LAN TCP and UDP(not tested) traffic to
                            port. (usually used with '--dns')
    
  WiFi hotspot options:
    --ap <wifi interface> <SSID>
                            Create WiFi access point
    -p, --password <password>   
                            WiFi password
    --qr                    Show WiFi QR code in terminal (need qrencode)
    
    --hidden                Hide access point (not broadcast SSID)
    --no-virt               Do not create virtual interface
                            Using this you can't use same wlan interface
                            for both Internet and AP
    --virt-name <name>      Set name of virtual interface
    -c <channel>            Channel number (default: 1)
    --country <code>        Set two-letter country code for regularity
                            (example: US)
    --freq-band <GHz>       Set frequency band: 2.4 or 5 (default: 2.4)
    --driver                Choose your WiFi adapter driver (default: nl80211)
    -w <WPA version>        '2' for WPA2, '1' for WPA, '1+2' for both
                            (default: 2)
    --psk                   Use 64 hex digits pre-shared-key instead of
                            passphrase
    --mac-filter            Enable WiFi hotspot MAC address filtering
    --mac-filter-accept     Location of WiFi hotspot MAC address filter list
                            (defaults to /etc/hostapd/hostapd.accept)
    --hostapd-debug <level> 1 or 2. Passes -d or -dd to hostapd
    --isolate-clients       Disable wifi communication between clients
    
    --ieee80211n            Enable IEEE 802.11n (HT)
    --ieee80211ac           Enable IEEE 802.11ac (VHT)
    --ht_capab <HT>         HT capabilities (default: [HT40+])
    --vht_capab <VHT>       VHT capabilities
    
    --no-haveged            Do not run haveged automatically when needed

  Instance managing:
    --daemon                Run in background
    -l, --list-running      Show running instances
    --lc, --list-clients <id|interface>     
                            List clients of an instance. Or list neighbors of
                            an interface, even if it isn't handled by us.
                            (passive mode)
    --stop <id>             Stop a running instance
        For <id> you can use PID or subnet interface name.
        You can get them with '--list-running'

Notice

    Notice 1:   This script assume your host's default policy won't forward
                packets, so the script won't explictly ban forwarding in any
                mode. In some unexpected case (eg. mistaken configurations) may
                cause unwanted packets leakage between 2 networks, which you
                should be aware of if you want isolated network

What changes are done to Linux system

On exit of a linux-router instance, script will do cleanup, i.e. undo most changes to system. Though, some changes (if needed) will not be undone, which are:

/proc/sys/net/ipv4/ip_forward = 1 and /proc/sys/net/ipv6/conf/all/forwarding = 1
dnsmasq in Apparmor complain mode
hostapd in Apparmor complain mode
Kernel module nf_nat_pptp loaded
The wifi device which is used to create hotspot is rfkill unblocked
WiFi country code, if user assigns

Meet contributor(s) and become one of them

Visit my homepage to see more tools and projects .

Buy me a coffee , this project took me lots of time! ( 扫码领红包并打赏一个!)

( ^_^) o自自o (^_^ )

Bisides, thank create_ap by oblique. This script was forked from create_ap. Now they are quite different. (See history branch for how I modified create_ap). Also thank those who contributed to that project.

You can be contributor, too!

There're some TO-DOs listed, in both readme TODO and in the code file
Also some unfulfilled enhancements in the Issues
Contributions are not limited to coding. There're some posts and questions that need more people to answer

TODO

Sooner is better:

Detect firewalld and make sure it won't interfere our interface

Future:

WPA3
Global IPv6
Explictly ban forwarding if not needed
Bring bridging method back

License

linux-router is LGPL licensed

linux-router
Copyright (C) 2018  garywill

This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA

Upstream create_ap was BSD licensed

Copyright (c) 2013, oblique
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

* Redistributions of source code must retain the above copyright notice, this
  list of conditions and the following disclaimer.

* Redistributions in binary form must reproduce the above copyright notice,
  this list of conditions and the following disclaimer in the documentation
  and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.