// CreateBridgeIface creates a network bridge interface on the host system with the name `ifaceName`,
// and attempts to configure it with an address which doesn't conflict with any other interface on the host.
// If it can't find an address which doesn't conflict, it will return an error.
func CreateBridgeIface(config *DaemonConfig) error {
addrs := []string{
// Here we don't follow the convention of using the 1st IP of the range for the gateway.
// This is to use the same gateway IPs as the /24 ranges, which predate the /16 ranges.
// In theory this shouldn't matter - in practice there's bound to be a few scripts relying
// on the internal addressing or other stupid things like that.
// The shouldn't, but hey, let's not break them unless we really have to.
"172.17.42.1/16", // Don't use 172.16.0.0/16, it conflicts with EC2 DNS 172.16.0.23
"10.0.42.1/16", // Don't even try using the entire /8, that's too intrusive
"10.1.42.1/16",
"10.42.42.1/16",
"172.16.42.1/24",
"172.16.43.1/24",
"172.16.44.1/24",
"10.0.42.1/24",
"10.0.43.1/24",
"192.168.42.1/24",
"192.168.43.1/24",
"192.168.44.1/24",
}
nameservers := []string{}
resolvConf, _ := utils.GetResolvConf()
// we don't check for an error here, because we don't really care
// if we can't read /etc/resolv.conf. So instead we skip the append
// if resolvConf is nil. It either doesn't exist, or we can't read it
// for some reason.
if resolvConf != nil {
nameservers = append(nameservers, utils.GetNameserversAsCIDR(resolvConf)...)
}
var ifaceAddr string
for _, addr := range addrs {
_, dockerNetwork, err := net.ParseCIDR(addr)
if err != nil {
return err
}
routes, err := netlink.NetworkGetRoutes()
if err != nil {
return err
}
if err := checkRouteOverlaps(routes, dockerNetwork); err == nil {
if err := checkNameserverOverlaps(nameservers, dockerNetwork); err == nil {
ifaceAddr = addr
break
}
} else {
utils.Debugf("%s: %s", addr, err)
}
}
if ifaceAddr == "" {
return fmt.Errorf("Could not find a free IP address range for interface '%s'. Please configure its address manually and run 'docker -b %s'", config.BridgeIface, config.BridgeIface)
}
utils.Debugf("Creating bridge %s with network %s", config.BridgeIface, ifaceAddr)
if err := netlink.NetworkLinkAdd(config.BridgeIface, "bridge"); err != nil {
return fmt.Errorf("Error creating bridge: %s", err)
}
iface, err := net.InterfaceByName(config.BridgeIface)
if err != nil {
return err
}
ipAddr, ipNet, err := net.ParseCIDR(ifaceAddr)
if err != nil {
return err
}
if netlink.NetworkLinkAddIp(iface, ipAddr, ipNet); err != nil {
return fmt.Errorf("Unable to add private network: %s", err)
}
if err := netlink.NetworkLinkUp(iface); err != nil {
return fmt.Errorf("Unable to start network bridge: %s", err)
}
if config.EnableIptables {
// Enable NAT
if output, err := iptables.Raw("-t", "nat", "-A", "POSTROUTING", "-s", ifaceAddr,
"!", "-d", ifaceAddr, "-j", "MASQUERADE"); err != nil {
return fmt.Errorf("Unable to enable network bridge NAT: %s", err)
} else if len(output) != 0 {
return fmt.Errorf("Error iptables postrouting: %s", output)
}
// Accept incoming packets for existing connections
if output, err := iptables.Raw("-I", "FORWARD", "-o", config.BridgeIface, "-m", "conntrack", "--ctstate", "RELATED,ESTABLISHED", "-j", "ACCEPT"); err != nil {
return fmt.Errorf("Unable to allow incoming packets: %s", err)
} else if len(output) != 0 {
return fmt.Errorf("Error iptables allow incoming: %s", output)
}
// Accept all non-intercontainer outgoing packets
if output, err := iptables.Raw("-I", "FORWARD", "-i", config.BridgeIface, "!", "-o", config.BridgeIface, "-j", "ACCEPT"); err != nil {
return fmt.Errorf("Unable to allow outgoing packets: %s", err)
} else if len(output) != 0 {
return fmt.Errorf("Error iptables allow outgoing: %s", output)
}
}
return nil
}
// CreateBridgeIface creates a network bridge interface on the host system with the name `ifaceName`,
// and attempts to configure it with an address which doesn't conflict with any other interface on the host.
// If it can't find an address which doesn't conflict, it will return an error.
func CreateBridgeIface(config *DaemonConfig) error {
addrs := []string{
// Here we don't follow the convention of using the 1st IP of the range for the gateway.
// This is to use the same gateway IPs as the /24 ranges, which predate the /16 ranges.
// In theory this shouldn't matter - in practice there's bound to be a few scripts relying
// on the internal addressing or other stupid things like that.
// The shouldn't, but hey, let's not break them unless we really have to.
"172.17.42.1/16", // Don't use 172.16.0.0/16, it conflicts with EC2 DNS 172.16.0.23
"10.0.42.1/16", // Don't even try using the entire /8, that's too intrusive
"10.1.42.1/16",
"10.42.42.1/16",
"172.16.42.1/24",
"172.16.43.1/24",
"172.16.44.1/24",
"10.0.42.1/24",
"10.0.43.1/24",
"192.168.42.1/24",
"192.168.43.1/24",
"192.168.44.1/24",
}
var ifaceAddr string
for _, addr := range addrs {
_, dockerNetwork, err := net.ParseCIDR(addr)
if err != nil {
return err
}
routes, err := netlink.NetworkGetRoutes()
if err != nil {
return err
}
if err := checkRouteOverlaps(routes, dockerNetwork); err == nil {
ifaceAddr = addr
break
} else {
utils.Debugf("%s: %s", addr, err)
}
}
if ifaceAddr == "" {
return fmt.Errorf("Could not find a free IP address range for interface '%s'. Please configure its address manually and run 'docker -b %s'", config.BridgeIface, config.BridgeIface)
}
utils.Debugf("Creating bridge %s with network %s", config.BridgeIface, ifaceAddr)
if err := netlink.NetworkLinkAdd(config.BridgeIface, "bridge"); err != nil {
return fmt.Errorf("Error creating bridge: %s", err)
}
iface, err := net.InterfaceByName(config.BridgeIface)
if err != nil {
return err
}
ipAddr, ipNet, err := net.ParseCIDR(ifaceAddr)
if err != nil {
return err
}
if netlink.NetworkLinkAddIp(iface, ipAddr, ipNet); err != nil {
return fmt.Errorf("Unable to add private network: %s", err)
}
if err := netlink.NetworkLinkUp(iface); err != nil {
return fmt.Errorf("Unable to start network bridge: %s", err)
}
if config.EnableIptables {
if err := iptables.Raw("-t", "nat", "-A", "POSTROUTING", "-s", ifaceAddr,
"!", "-d", ifaceAddr, "-j", "MASQUERADE"); err != nil {
return fmt.Errorf("Unable to enable network bridge NAT: %s", err)
}
}
return nil
}