Difference between revisions of "Sharing PPP Connection"

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(Requirements)
(Sharing via wired ethernet: updated ip_forward instruction)
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[[Category:Networking (English)]]
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[[Category:Networking]]
[[Category:HOWTOs (English)]]
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{{Merge|Internet Sharing|Just a specific case of the topic described there.}}
  
=Requirements=
+
== Requirements ==
The following programs must have been installed in order to share the ppp connection:
+
Before proceeding, you must make sure:
# Programs for configuring generic network interface card (package '''net-tools''')
+
# You must have a working PPP connection.
# The '''iptables''' program which is used to manipulate how data is passed through your machine from your clients and back (package '''iptables''')
+
# You must have an extra Ethernet interface card in your computer with which to share your connection.
# '''dnsmasq''' software for acting as a DHCP and DNS caching server (package '''dnsmasq''')
+
# If you want to share the ppp connection with more computers you need to setup a network bridge. (package '''bridge-utils''')
+
  
 +
== Installing ==
 +
The following packages must be [[Pacman|installed]] from the [[official repositories]] for both Wired and Wireless sharing:
 +
* {{Pkg|iptables}}: for controlling packets in your network.
 +
* {{Pkg|dnsmasq}}: for acting as a DHCP and DNS caching server.
 +
* {{Pkg|bridge-utils}}: for setting up a network bridge.
  
The following conditions must also have been met:
+
Depending on whether you want to share a wireless or wired connection, you also have to install:
# You must have a working ppp connection
+
* '''wired''': {{Pkg|iproute2}} or {{Pkg|net-tools}} (this article uses {{ic|iproute2}} since {{ic|net-tools}} is deprecated).
# You must have a working an extra eth interface card (in terms of "can be used in Linux")
+
* '''wireless''': {{Pkg|iw}} or {{Pkg|wireless_tools}} (this article uses {{ic|iw}} since {{ic|wireless_tools}} is deprecated).
  
=Instructions=
+
== Sharing via wired ethernet ==
  
<ol>
+
* Set the PPP connection up.
<li>Set the ppp connection up.</li>
+
: You can assign an IP address to the interface as usual, by running (as root):
you can assign an ip address to the interface as usual, by running (again, as root): <pre>ifconfig eth1 192.168.0.254</pre>
+
# ip addr add 192.168.0.254 dev eth0
<li>Set the kernel to router mode. This is done by running as root: <pre>echo 1 > /proc/sys/net/ipv4/ip_forward</pre></li>
+
* Set the kernel to router mode. This is done by running:
<li>Configure '''dnsmasqd'''. Make the following changes to /etc/dnsmasq.conf (uncomment if necessary): <pre>
+
# sysctl net.ipv4.ip_forward=1
 +
* Configure [[dnsmasq]]. Make the following changes to {{ic|/etc/dnsmasq.conf}} (uncomment if necessary):
 +
{{hc|/etc/dnsmasq.conf|<nowiki>
 
domain-needed
 
domain-needed
 
bogus-priv
 
bogus-priv
interface=eth1 (or whatever interface your wlan is)
+
interface=eth0 # change to your chosen interface
dhcp-range=192.168.0.1,192.168.0.100,12h
+
dhcp-range=192.168.0.1,192.168.0.100,12h</nowiki>
</pre></li>
+
}}
<li>Start the dnsmasqd, as root: <pre>/etc/rc.d/dnsmasq start</pre></li>
+
* [[Daemons#Managing_daemons|Start]] the '''dnsmasq''' daemon.
<li>Finally, set firewall to forward connections to and from the Internet for clients connecting to your wlan. This is done by issuing (you guessed it right, as root again): <pre>iptables -t nat -A POSTROUTING -o ppp0 -j MASQUERADE</pre> In the above the '''''ppp0''''' interface is the used ppp interface, you can substitute it for yours if needed.</li>
+
* Finally, set firewall to forward connections to and from the Internet for clients connecting to your WLAN. This is done by issuing:
<li>You are done! Happy surfing</li>
+
# iptables -t nat -A POSTROUTING -o ppp0 -j MASQUERADE
</ol>
+
:In the above the '''ppp0''' interface is the used PPP interface, you can substitute it for yours if needed.
 +
* You are done! Happy surfing!
  
{{Warning|The previous configuration has no security options enabled!<br>If you are using firewall, you should adapt this documentation to suit your needs.<br>Same applies also to setting up keys for wlan interface.}}
+
{{Warning|The previous configuration has no security options enabled. If you are using a firewall, you should adapt this documentation to suit your needs. Same applies also to setting up keys for WLAN interface.}}
  
=See Also=
+
=== Network bridge ===
*[[Internet Share]]
+
Let's assume your PPP connection is on '''eth0''', and you want to share the connection on '''eth1''' and '''eth2'''.
*[[Simple stateful firewall HOWTO]]
+
 
*[[NAT'ing firewall - Share your broadband connection]]
+
# ip addr add 0.0.0.0 dev eth1  # remove IP from eth0
*[[Wireless Setup]]
+
# ip link set eth1 up          # ensure the interface is up
*[[USB 3G Modem]]
+
 
 +
# ip addr add 0.0.0.0 dev eth2  # remove IP from eth1
 +
# ip link set eth2 up          # ensure the interface is up
 +
 
 +
# brctl addbr br0              # create br0 node
 +
# brctl addif br0 eth1          # add eth0 to bridge br0
 +
# brctl addif br0 eth2          # add eth1 to bridge br0
 +
 
 +
# ip addr add 192.168.0.254 dev br0
 +
change your interface in {{ic|dnsmasq.conf}} to '''br0''':
 +
interface=br0
 +
and [[Daemons#Managing_daemons|restart]] the '''dnsmasq''' daemon.
 +
 
 +
Now you should be able to connect to the internet using '''eth1''' or '''eth2'''.
 +
 
 +
== Sharing via WLAN ==
 +
 
 +
{{Warning|These instructions create '''unencrypted''' ad-hoc network. See [[Ad-hoc networking#WPA supplicant]] for method using WPA1 encryption. For better security, create an [[Software Access Point|access point]] secured by WPA2.}}
 +
 
 +
* Set up the PPP connection.
 +
* Set up the WLAN connection: choose an SSID and select Ad-hoc as network type. In the following it is assumed that you are using the '''wlan0''' interface.
 +
 
 +
: Set the '''wlan0''' interface up address for example 192.168.0.254. Setting up the interface is usually done by running:
 +
# iw wlan0 set type ibss
 +
# iw wlan0 ibss join MyFreeWlan
 +
 
 +
: After that you can assign an IP address to the interface as usual, by running:
 +
# ip addr add 192.168.0.254 dev wlan0
 +
: Please note that different wlan cards may be configured differently and one should adapt this documentation accordingly.
 +
* Set the kernel to router mode. This is done by running:
 +
# echo 1 > /proc/sys/net/ipv4/ip_forward
 +
* Configure '''dnsmasq'''. Make the following changes to {{ic|/etc/dnsmasq.conf}} (uncomment if necessary):
 +
{{hc|etc/dnsmasq.conf|<nowiki>
 +
domain-needed
 +
bogus-priv
 +
interface=wlan0    # change to your interface
 +
dhcp-range=192.168.0.1,192.168.0.100,12h</nowiki>
 +
}}
 +
* [[Daemons#Managing_daemons|Start]] the '''dnsmasq''' daemon.
 +
* Finally, set firewall to forward connections to and from the Internet for clients connecting to your WLAN. This is done by issuing:
 +
# iptables -t nat -A POSTROUTING -o ppp0 -j MASQUERADE
 +
 
 +
: In the above the '''ppp0''' interface is assumed to be the used PPP interface, you can substitute it for yours if needed.
 +
* You are done! Happy surfing!
 +
 
 +
{{Warning|The previous configuration has no security options enabled! If you are using firewall, you should adapt this documentation to suit your needs. Same applies also to setting up keys for wlan interface.}}
 +
 
 +
== Sharing script ==
 +
A quick script for sharing '''eth0''' over '''wlan0''' on an ad-hoc network.
 +
{{hc|ethoverwlan.sh|
 +
#!/bin/bash
 +
 
 +
iw wlan0 set type ibss
 +
iw wlan0 ibss join proxywlan
 +
ip addr add 192.168.0.254 dev wlan0
 +
ip link set wlan0 up
 +
iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
 +
echo 1 > /proc/sys/net/ipv4/ip_forward
 +
}}
 +
 
 +
== See also ==
 +
* [[Simple stateful firewall]]
 +
* [[Router]]
 +
* [[Wireless Setup]]
 +
* [[USB 3G Modem]]
 +
* [http://go2linux.garron.me/linux/2011/03/share-your-3g-internet-connection-over-wifi-linux-ipod-touch-925 Share your 3G Internet connection over wifi]

Revision as of 10:42, 14 November 2013

Merge-arrows-2.pngThis article or section is a candidate for merging with Internet Sharing.Merge-arrows-2.png

Notes: Just a specific case of the topic described there. (Discuss in Talk:Sharing PPP Connection#)

Requirements

Before proceeding, you must make sure:

  1. You must have a working PPP connection.
  2. You must have an extra Ethernet interface card in your computer with which to share your connection.

Installing

The following packages must be installed from the official repositories for both Wired and Wireless sharing:

  • iptables: for controlling packets in your network.
  • dnsmasq: for acting as a DHCP and DNS caching server.
  • bridge-utils: for setting up a network bridge.

Depending on whether you want to share a wireless or wired connection, you also have to install:

  • wired: iproute2 or net-tools (this article uses iproute2 since net-tools is deprecated).
  • wireless: iw or wireless_tools (this article uses iw since wireless_tools is deprecated).

Sharing via wired ethernet

  • Set the PPP connection up.
You can assign an IP address to the interface as usual, by running (as root):
# ip addr add 192.168.0.254 dev eth0
  • Set the kernel to router mode. This is done by running:
# sysctl net.ipv4.ip_forward=1
  • Configure dnsmasq. Make the following changes to /etc/dnsmasq.conf (uncomment if necessary):
/etc/dnsmasq.conf
domain-needed
bogus-priv
interface=eth0 # change to your chosen interface
dhcp-range=192.168.0.1,192.168.0.100,12h
  • Start the dnsmasq daemon.
  • Finally, set firewall to forward connections to and from the Internet for clients connecting to your WLAN. This is done by issuing:
# iptables -t nat -A POSTROUTING -o ppp0 -j MASQUERADE
In the above the ppp0 interface is the used PPP interface, you can substitute it for yours if needed.
  • You are done! Happy surfing!
Warning: The previous configuration has no security options enabled. If you are using a firewall, you should adapt this documentation to suit your needs. Same applies also to setting up keys for WLAN interface.

Network bridge

Let's assume your PPP connection is on eth0, and you want to share the connection on eth1 and eth2.

# ip addr add 0.0.0.0 dev eth1  # remove IP from eth0
# ip link set eth1 up           # ensure the interface is up
# ip addr add 0.0.0.0 dev eth2  # remove IP from eth1
# ip link set eth2 up           # ensure the interface is up
# brctl addbr br0               # create br0 node
# brctl addif br0 eth1          # add eth0 to bridge br0
# brctl addif br0 eth2          # add eth1 to bridge br0
# ip addr add 192.168.0.254 dev br0

change your interface in dnsmasq.conf to br0:

interface=br0 

and restart the dnsmasq daemon.

Now you should be able to connect to the internet using eth1 or eth2.

Sharing via WLAN

Warning: These instructions create unencrypted ad-hoc network. See Ad-hoc networking#WPA supplicant for method using WPA1 encryption. For better security, create an access point secured by WPA2.
  • Set up the PPP connection.
  • Set up the WLAN connection: choose an SSID and select Ad-hoc as network type. In the following it is assumed that you are using the wlan0 interface.
Set the wlan0 interface up address for example 192.168.0.254. Setting up the interface is usually done by running:
# iw wlan0 set type ibss
# iw wlan0 ibss join MyFreeWlan
After that you can assign an IP address to the interface as usual, by running:
# ip addr add 192.168.0.254 dev wlan0
Please note that different wlan cards may be configured differently and one should adapt this documentation accordingly.
  • Set the kernel to router mode. This is done by running:
# echo 1 > /proc/sys/net/ipv4/ip_forward
  • Configure dnsmasq. Make the following changes to /etc/dnsmasq.conf (uncomment if necessary):
etc/dnsmasq.conf
domain-needed
bogus-priv
interface=wlan0    # change to your interface
dhcp-range=192.168.0.1,192.168.0.100,12h
  • Start the dnsmasq daemon.
  • Finally, set firewall to forward connections to and from the Internet for clients connecting to your WLAN. This is done by issuing:
# iptables -t nat -A POSTROUTING -o ppp0 -j MASQUERADE
In the above the ppp0 interface is assumed to be the used PPP interface, you can substitute it for yours if needed.
  • You are done! Happy surfing!
Warning: The previous configuration has no security options enabled! If you are using firewall, you should adapt this documentation to suit your needs. Same applies also to setting up keys for wlan interface.

Sharing script

A quick script for sharing eth0 over wlan0 on an ad-hoc network.

ethoverwlan.sh
#!/bin/bash

iw wlan0 set type ibss
iw wlan0 ibss join proxywlan
ip addr add 192.168.0.254 dev wlan0
ip link set wlan0 up
iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
echo 1 > /proc/sys/net/ipv4/ip_forward

See also