internetsharing(8) [osx man page]
InternetSharing(8) BSD System Manager's Manual InternetSharing(8) NAME
InternetSharing -- simple NAT/router configuration daemon SYNOPSIS
InternetSharing -d DESCRIPTION
InternetSharing is the back-end for the Internet Sharing feature. It is responsible for configuring the network interfaces, the DHCP server bootpd(8), the network address translation daemon natd(8), and the Internet domain name server named(8). named(8) is run in caching-only mode and allows the DHCP server to always offer the same DNS server address to the DHCP clients, regardless of the value of the actual DNS server addresses. The single command line option -d places additional debugging information to stdout/stderr. InternetSharing is launched by launchd(8) both at start-up and when the user turns Internet Sharing on in the Sharing preferences pane. By default, InternetSharing configures the IP addresses for non-AirPort interfaces starting at 192.168.2.1, walking up by one class C network (subnet mask 255.255.255.0) for each subsequent interface i.e. 192.168.3.1, 192.168.4.1, 192.168.5.1, and so on. The AirPort interface by default is assigned 10.0.2.1. CONFIGURATION
InternetSharing reads the property list com.apple.nat.plist stored in the /Library/Preferences/SystemConfiguration. Details of the com.apple.nat.plist are subject to change and are not completely documented here. The plist is a contract between the Sharing preferences pane and InternetSharing. Any details provided here are for informational purposes only. The plist is a dictionary with a single sub-dictionary called NAT containing properties to control which interfaces to use and other set- tings. It may also have a sub-dictionary called AirPort that is used to configure the AirPort interface when it is put into access point mode. One property worth mentioning is SharingNetworkNumberStart. This property controls the behavior of InternetSharing when it configures IP addresses for the local interfaces. The property is encoded as a string containing the dotted decimal network IP address, assumed to be a class C network. For example: <key>SharingNetworkNumberStart</key> <string>192.168.100.0</string> If the SharingNetworkNumberStart appears directly in the NAT dictionary, it controls the starting IP address chosen for the non-AirPort interfaces. If the property appears within the AirPort sub-dictionary, it controls the IP address assigned to the AirPort interface. The purpose of the property is to allow the user to avoid address collisions with existing NAT'd networks. SEE ALSO
bootpd(8), launchd(8), natd(8), named(8) Mac OS X Feburary 26, 2007 Mac OS X
Check Out this Related Man Page
IPCONFIG(8) BSD System Manager's Manual IPCONFIG(8) NAME
ipconfig -- view and control IP configuration state SYNOPSIS
ipconfig waitall ipconfig getifaddr interface-name ipconfig ifcount ipconfig getoption interface-name (option-name | option-code) ipconfig getpacket interface-name ipconfig getv6packet interface-name ipconfig setverbose level ipconfig set interface-name NONE ipconfig set interface-name (DHCP | BOOTP) ipconfig set interface-name (MANUAL | INFORM) ip-address subnet-mask ipconfig set interface-name NONE-V6 ipconfig set interface-name AUTOMATIC-V6 ipconfig set interface-name MANUAL-V6 ipv6-address prefix-length ipconfig set interface-name 6TO4 DESCRIPTION
ipconfig is a utility that communicates with the IPConfiguration agent to retrieve and set IP configuration parameters. It should only be used in a test and debug context. Using it for any other purpose is strongly discouraged. Public API's in the SystemConfiguration framework are currently the only supported way to access and control the state of IPConfiguration. The IPConfiguration agent is responsible for configuring and managing the IP addresses on direct, connectionless interfaces such as IEEE 802.3 Ethernet and IEEE 1394 FireWire. The IPConfiguration agent is a program bundle that is loaded and executed by the configd(8) process. The IPConfiguration agent implements the client side of the DHCP and BOOTP protocols described in RFC951, RFC1542, RFC2131, and RFC2132. It also assigns and maintains static IP addresses. It may also allocate and assign a link-local IP address if DHCP fails to acquire an IP address. In all cases, the IPConfiguration agent performs IP address conflict detection before assigning an IP address to an interface. COMMANDS
The ipconfig utility provides several commands: waitall Blocks until all network services have completed configuring, or have timed out in the process of configuring. This is only use- ful for initial system start-up time synchronization for legacy network services that are incapable of dealing with dynamic net- work configuration changes. getifaddr interface-name Prints to standard output the IP address for the first network service associated with the given interface. The output will be empty if no service is currently configured or active on the interface. ifcount Prints the number of interfaces that IPConfiguration is capable of configuring. The value that's printed will not change unless relevant network interfaces are either added to or removed from the system. getoption interface-name (option-name | option-code) Prints the BOOTP/DHCP option with the given name or option code integer value. See bootpd(8) for option code names. If an option has multiple values e.g. domain_name_server, only the first value is printed. getpacket interface-name Prints to standard output the DHCP/BOOTP packet that the client accepted from the DHCP/BOOTP server. This command is useful to check what the server provided, and whether the values are sensible. This command outputs nothing if DHCP/BOOTP is not active on the interface, or the attempt to acquire an IP address was unsuccessful. getv6packet interface-name Prints to standard output the latest DHCPv6 packet that the client accepted from the DHCPv6 server. In the case of stateful DHCPv6, it corresponds to the last packet from the server that contained addressing information. This command is useful to check what the server provided, and whether the values are sensible. This command outputs nothing if DHCPv6 is not active on the interface. set interface-name NONE set interface-name (DHCP | BOOTP) set interface-name (MANUAL | INFORM) ip-address subnet-mask set interface-name NONE-V6 set interface-name AUTOMATIC-V6 set interface-name MANUAL-V6 ipv6-address prefix-length set interface-name 6TO4 Sets the interface to have a new temporary network service of the given type. Any existing services on the interface for the particular protocol (IPv4 or IPv6) are first de-configured before the new service is instantiated. If NONE is specified, all existing IPv4 services are de-configured. If NONE-V6 is specified, all existing IPv6 services are de- configured. DHCP and BOOTP require no additional arguments. The IP address, subnet mask, router, and DNS information are retrieved automati- cally. Both MANUAL and INFORM require the specification of an IP address ip-address and a subnet mask subnet-mask. The INFORM service configures the IP address statically like MANUAL, but then broadcasts DHCP INFORM packets to retrieve DHCP option information. If the DHCP server responds and supplies a subnet mask, that subnet mask is used instead of the specified subnet-mask. AUTOMATIC-V6 requires no additional arguments. The IPv6 address, prefix length and router are retrieved automatically. MANUAL-V6 requires the specification of the IPv6 address ipv6-address and a prefix length prefix-length. 6TO4 only works on Six To Four (IFT_STF) interfaces e.g. stf0. If it is specified on a non-IFT_STF interface, it has the same effect as specifying NONE-V6. The set command requires root privileges. Note: The set command is very useful for debugging, but it can't be used to configure a persistent service. The temporary ser- vices that are created only remain until the next network configuration change occurs. See scselect(8). setverbose level Enables or disables verbose mode logging in the IPConfiguration agent. Specify a level value of 0 to disable verbose logging, the default. Specify a value of 1 to enable verbose logging. This setting is persistent across boots of the operating system. When enabled, verbose log files are generated in the directory /Library/Logs/CrashReporter. The filenames follow the naming con- vention com.apple.networking.IPConfiguration.log.<timestamp>. The setverbose command requires root privileges. EXAMPLES
# ipconfig getpacket en0 op = BOOTREPLY htype = 1 dp_flags = 0 hlen = 6 hops = 0 xid = 1956115059 secs = 0 ciaddr = 0.0.0.0 yiaddr = 192.168.4.10 siaddr = 192.168.4.1 giaddr = 0.0.0.0 chaddr = 0:3:93:7a:d7:5c sname = dhcp.mycompany.net file = options: Options count is 10 dhcp_message_type (uint8): ACK 0x5 server_identifier (ip): 192.168.4.1 lease_time (uint32): 0x164a subnet_mask (ip): 255.255.255.0 router (ip_mult): {192.168.4.1} domain_name_server (ip_mult): {192.168.4.1} domain_name (string): mycompany.net end (none): # ipconfig getoption en0 router 192.168.4.1 SEE ALSO
configd(8), bootpd(8), scselect(8) HISTORY
The ipconfig command first appeared in Mac OS X Version 10.0 Public Beta. Mac OS X March 27, 2013 Mac OS X