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== How Usually you supply public IP addresses to provide access your containers. Sometimes you don't want to do it (lack of IPs, etc.). This article describes how to use private IP addresses for VE to Internet ==containers.

== Prerequisites == Make sure that below prerequisites are met, otherwise it won't work for you! === IP conntracks === '''IP connection tracking should be enabled for CT0'''. For recent OpenVZ kernels (2.6.9 and later) connection tracking for CT0 is enabled by default, but it can be disabled by vzctl 4.7 and newer (because it has a negative impact on venet performance, see {{Bug|2755}}). So, make sure there is '''NO''' line like  options ip_conntrack ip_conntrack_disable_ve0=1or options nf_conntrack ip_conntrack_disable_ve0=1 in <code>/etc/modules.conf</code>, <code>/etc/modprobe.conf</code>, or any file under <code>/etc/modprobe.d/</code> (such as <code>/etc/modprobe.d/vz.conf</code>). '''If there is such a line, please'''#change <code>=1</code> to <code>=0</code> #reboot the node. === IP forwarding === '''IP forwarding should be turned on''' on the hardware node in order for container networking to work. Make sure it is turned on:  $ cat /proc/sys/net/ipv4/ip_forward 1 Output should be '1'. If it is '0', enable IP forwarding as it is described in [[Quick installation#sysctl]]. NOTE: '''Ubuntu''' made some changes to the syntax for NAT. See this link if you are needing to enable NAT on an Ubuntu host : [https://bugs.launchpad.net/ubuntu/+source/procps/+bug/84537 Launchpad] The syntax of /etc/sysctl.conf has changed to: <pre>net.ipv4.conf.default.forwarding=1net.ipv4.conf.all.forwarding=1</pre> ===Enable iptables in OpenVZ 7/Virtuozzo 7=== If you use OpenVZ 7/Virtuozzo 7 and want to manage iptables through iptables-services you must disable firewalld and enable iptables:  # systemctl stop firewalld # systemctl mask firewalld # yum install iptables-services # systemctl enable iptables  == How to create the container and attach network properties to it == Create the container:  # prlctl create 100700 --vmtype ct Attach the internal IP address and DNS server:  # prlctl set 100700 --ipadd 192.168.0.101/24 # prlctl set 100700 --nameserver 8.8.8.8 Start the container:  # prlctl start 100700 == How to provide access for container to the Internet == To enable the [[VEcontainer]]s, which have only internal IP addresses, to access the Internet, SNAT (Source Network Address Translation, also known as IP masquerading) should be configured on the [[Hardware Node]]. This is ensured by the standard Linux <tt>iptables</tt> utility.  To perform a simple SNAT setup, execute the following command on the [[Hardware Node]]:

where <tt>src_net</tt> is a range of IP addresses of VEs containers to be translated by SNAT, and <tt>ip_address</tt> is the external IP address of your [[Hardware Node]]. The format of src_net is xx.xx.xx.xx/xx ([[w:CIDR|CIDR notation]]). For example:<pre># iptables -t nat -A POSTROUTING -s 192.168.2.0/24 -o eth0 -j SNAT --to ip_address</pre> Multiple rules are allowed, for example, in case you wish to specify several ranges of IP addresses. If you are using a number of physical network interfaces on the [[Hardware Node|Node]], you may need to specify a different interface for outgoing connections, e.g. <tt>-o eth2</tt>.

To make all IP addresses to be translated by SNAT (not only the ones of [[VEcontainer]]s with private addresses), you should type the following string:

{{Note|If the above is not working then check if one of the following solutions does the trick.}}Or you can just use: 1. If you are using stable (currently 2.6.8 # iptables -t nat -A POSTROUTING -o eth0 -based) kernel, then j MASQUERADE === Save new iptables rules === Do not forget to enable SNAT for the VEs on save your local network new iptables rules  # service iptables save # service iptables restart === Firewall === For Debian hardware node, you may need to explicitly enable connection tracking in [[VE0]]allow a forward rule. Make sure that The table still being the following string default table (filter) but the chain is present in the <tt>FORWARD:  # iptables -A FORWARD -s 192.168.2.0/etc24 -j ACCEPT # iptables -A FORWARD -d 192.168.2.0/modprobe.conf<24 -j ACCEPT For default RedHat/tt> fileCentOS firewall, allow outgoing connections from your containers, for example:<pre>options ip_conntrack ip_conntrack_enable_ve0= # iptables -A RH-Firewall-1-INPUT -s 192.168.2.0/24 -j ACCEPT</pre>=== Test ===

In case it is not, add this string Now you should be able to the file by means of any text editor (for example, vi). This setting is not needed for kernels more recent than 2.6.8, since connection tracking for [[VE0]] is enabled by default in those kernels.reach internet from your container:

2. For unknown reasons the above didn't work on a Debian host. The solution is to do it in an init.d script as follows:<pre>modprobe ip_conntrack ip_conntrack_enable_ve0=1</pre> # prlctl enter 100700 Make sure that this module is loaded before any of the other iptables-modules ar loaded! Also remember that if this module is loaded without the option, unloading and reloading doesn't work! You need to reboot the computer # ping openvz.org

== How to provide access from Internet to a VE container ==

In addition, to make some services in VE container with private IP address be accessible from the Internet, DNAT (Destination Network Address Translation) should be configured on the [[Hardware Node]]. To perform a simple DNAT setup, execute the following command on the [[Hardware Node]]:

# iptables -t nat -A PREROUTING -p tcp -d ip_address --port dport port_num \

where <tt>ve_address</tt> is an IP address of the VEcontainer, <tt>dst_port_num</tt> is a tcp port which requires service use, <tt>ip_address</tt> is the external (public) IP address of your [[Hardware Node]], and <tt>port_num</tt> is a tcp port of [[Hardware Node]], which will be used for Internet connections to private VE container service. Note that this setup makes the service which is using <tt>port_num</tt> on the [[Hardware Node]] be unaccessible from the Internet. Also note that SNAT translation is required too.

For example, if you need a web server in a VE container to be accessible from outside and, at the same time, keep a web server on the [[Hardware Node]] be accessible, use the following config:

Is need add GATEWAY in /etc/sysconfig/network-script/interface (IP of host that provide access internet). After applying this, you'll see VEcontainer' web server at <code><nowiki>http://ip_address:8080/</nowiki></code>. {{Note|this rule will only work for external clients, i.e. connections originating from a different host — so you can not test if it works locally.}} {{Note|If you get any errors relating to: <code>iptables: No chain/target/match by that name</code>double check to see if you have all the iptables/netfilter modules loaded properly. I had to <code> modprobe xt_tcpudp </code> before getting it to work.}}