Difference between revisions of "Internet sharing"
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[[it:Internet Share]] | [[it:Internet Share]] | ||
[[ru:Internet Share]] | [[ru:Internet Share]] | ||
− | + | This article explains how to share the internet connection from one machine to other(s). | |
− | |||
− | + | == Requirements == | |
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− | |||
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− | |||
− | + | * The machine acting as server should have an additional network device. | |
− | + | * That network device should be connected to the machines that are going to receive internet access. They can be one or more machines. To be able to share internet to several machines a [[Wikipedia:Network switch|switch]] is required. If you are sharing to only one machine, a [[Wikipedia:Ethernet crossover cable|crossover cable]] is sufficient. | |
− | |||
− | |||
− | + | {{Note|If one of the two computers has a gigabit ethernet card, a crossover cable is not necessary and a regular ethernet cable should be enough}} | |
− | + | == Configuration == | |
− | + | This section assumes, that the network device connected to the client computer(s) is named '''''net0''''' and the network device connected to the internet as '''''internet0'''''. | |
− | + | {{Tip|You can rename your devices to this scheme using [[Udev#Setting static device names]].}} | |
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− | + | === Static IP address === | |
− | + | Assign an static IPv4 address to the interface connected to the other machines. The first 3 bytes of this address cannot be exactly the same as those of another interface. | |
+ | # ip link set up dev net0 | ||
+ | # ip addr add 139.96.30.100/24 dev net0 # arbitrary address | ||
− | + | To have your static ip assigned at boot, you can use [[netctl]]. | |
− | + | === Enable packet forwarding === | |
− | |||
− | |||
− | |||
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− | + | Enter this command to temporarily enable packet forwarding: | |
− | + | # sysctl net.ipv4.ip_forward=1 | |
− | |||
− | |||
− | |||
− | + | Edit {{ic|/etc/sysctl.conf}} to make the previous change persistent after a reboot. | |
+ | {{hc|/etc/sysctl.conf|<nowiki> | ||
+ | net.ipv4.ip_forward=1 | ||
+ | </nowiki>}} | ||
− | < | + | If you are using ipv6, use this: |
− | + | {{hc|/etc/sysctl.conf|<nowiki> | |
− | + | net.ipv6.conf.default.forwarding=1 | |
− | + | net.ipv6.conf.all.forwarding=1 | |
− | + | </nowiki>}} | |
− | + | === Enable NAT === | |
− | |||
− | |||
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− | |||
− | + | [[pacman|Install]] the package {{Pkg|iptables}} from the [[Official Repositories|official repositories]]. Use iptables to enable NAT: | |
− | {{Note| Of course, this also works with a mobile broadband connection (usually called ppp0 on PC1)}} | + | # iptables -t nat -A POSTROUTING -o internet0 -j MASQUERADE |
+ | # iptables-save > /etc/iptables/iptables.rules | ||
+ | # systemctl start iptables | ||
+ | |||
+ | {{Note|Of course, this also works with a mobile broadband connection (usually called ppp0 on PC1).}} | ||
+ | |||
+ | {{Tip|You can set {{ic|iptables.service}} to [[Daemon|auto start at boot]].}} | ||
+ | |||
+ | Read the [[iptables]] article for more information. There's also an excellent guide on iptables [[Simple stateful firewall]]. | ||
+ | |||
+ | === Assigning ip addresses to the client pc(s) === | ||
+ | |||
+ | If you are planning to regularly have several machines using the internet shared by this machine, then is a good idea to install a [[Wikipedia:dhcp|dhcp server]]. | ||
+ | |||
+ | You can read the [[dhcpd]] wiki article, to add a dhcp server. Then, install the [[dhcpcd]] client on every client pc. | ||
+ | |||
+ | If you are not planing to use this setup regularly, you can manually add an ip to each client instead. | ||
+ | |||
+ | ==== Manually adding an ip ==== | ||
+ | |||
+ | Instead of using dhcp, on each client pc, add an ip address and the default route: | ||
+ | # ip addr add 139.96.30.120/24 dev eth0 | ||
+ | # ip link set up dev eth0 | ||
+ | # ip route add default via 139.96.30.100 dev eth0 | ||
+ | |||
+ | Add a nameserver: | ||
+ | # echo "nameserver <nameserver ip>" >> /etc/resolv.conf | ||
+ | |||
+ | You can figure out the address of the nameserver by looking into the {{ic|/etc/resolv.conf}} of the server, if its Internet connection is already established. | ||
+ | |||
+ | If you don't have a nameserver, you can use any of the free public DNS servers, which are relatively fast: | ||
+ | * [https://code.google.com/speed/public-dns/ Google Public DNS] | ||
+ | ** 8.8.8.8 | ||
+ | ** 8.8.4.4 | ||
+ | ** [2001:4860:4860::8888] | ||
+ | ** [2001:4860:4860::8844] | ||
+ | * [https://opendns.com OpenDNS]: | ||
+ | ** 208.67.222.222 | ||
+ | ** 208.67.220.220 | ||
+ | ** [2620:0:ccc::2] | ||
+ | ** [2620:0:ccd::2] | ||
+ | |||
+ | {{Note|Bracket notation must be used for IPv6 addresses in resolv.conf.}} | ||
That's it. The client PC should now have Internet. | That's it. The client PC should now have Internet. | ||
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If you are able to connect the two PCs but cannot send data (for example, if the client PC makes a DHCP request to the server PC, the server PC receives the request and offers an IP to the client, but the client does not accept it, timing out instead), check that you don't have other [[Iptables]] rules [https://bbs.archlinux.org/viewtopic.php?pid=1093208 interfering]. | If you are able to connect the two PCs but cannot send data (for example, if the client PC makes a DHCP request to the server PC, the server PC receives the request and offers an IP to the client, but the client does not accept it, timing out instead), check that you don't have other [[Iptables]] rules [https://bbs.archlinux.org/viewtopic.php?pid=1093208 interfering]. | ||
− | ==See also== | + | == See also == |
− | *[[Sharing | + | |
− | *[[Simple stateful firewall]] | + | * [[Ad-hoc networking]] |
− | *[[Router]] | + | * [[Sharing PPP Connection]] |
− | *[[USB 3G Modem]] | + | * [[Simple stateful firewall]] |
+ | * [[Router]] | ||
+ | * [[USB 3G Modem]] |
Revision as of 12:06, 30 August 2013
This article explains how to share the internet connection from one machine to other(s).
Contents
Requirements
- The machine acting as server should have an additional network device.
- That network device should be connected to the machines that are going to receive internet access. They can be one or more machines. To be able to share internet to several machines a switch is required. If you are sharing to only one machine, a crossover cable is sufficient.
Configuration
This section assumes, that the network device connected to the client computer(s) is named net0 and the network device connected to the internet as internet0.
Static IP address
Assign an static IPv4 address to the interface connected to the other machines. The first 3 bytes of this address cannot be exactly the same as those of another interface.
# ip link set up dev net0 # ip addr add 139.96.30.100/24 dev net0 # arbitrary address
To have your static ip assigned at boot, you can use netctl.
Enable packet forwarding
Enter this command to temporarily enable packet forwarding:
# sysctl net.ipv4.ip_forward=1
Edit /etc/sysctl.conf
to make the previous change persistent after a reboot.
/etc/sysctl.conf
net.ipv4.ip_forward=1
If you are using ipv6, use this:
/etc/sysctl.conf
net.ipv6.conf.default.forwarding=1 net.ipv6.conf.all.forwarding=1
Enable NAT
Install the package iptables from the official repositories. Use iptables to enable NAT:
# iptables -t nat -A POSTROUTING -o internet0 -j MASQUERADE # iptables-save > /etc/iptables/iptables.rules # systemctl start iptables
iptables.service
to auto start at boot.Read the iptables article for more information. There's also an excellent guide on iptables Simple stateful firewall.
Assigning ip addresses to the client pc(s)
If you are planning to regularly have several machines using the internet shared by this machine, then is a good idea to install a dhcp server.
You can read the dhcpd wiki article, to add a dhcp server. Then, install the dhcpcd client on every client pc.
If you are not planing to use this setup regularly, you can manually add an ip to each client instead.
Manually adding an ip
Instead of using dhcp, on each client pc, add an ip address and the default route:
# ip addr add 139.96.30.120/24 dev eth0 # ip link set up dev eth0 # ip route add default via 139.96.30.100 dev eth0
Add a nameserver:
# echo "nameserver <nameserver ip>" >> /etc/resolv.conf
You can figure out the address of the nameserver by looking into the /etc/resolv.conf
of the server, if its Internet connection is already established.
If you don't have a nameserver, you can use any of the free public DNS servers, which are relatively fast:
- Google Public DNS
- 8.8.8.8
- 8.8.4.4
- [2001:4860:4860::8888]
- [2001:4860:4860::8844]
- OpenDNS:
- 208.67.222.222
- 208.67.220.220
- [2620:0:ccc::2]
- [2620:0:ccd::2]
That's it. The client PC should now have Internet.
Troubleshooting
If you are able to connect the two PCs but cannot send data (for example, if the client PC makes a DHCP request to the server PC, the server PC receives the request and offers an IP to the client, but the client does not accept it, timing out instead), check that you don't have other Iptables rules interfering.