TOPIC
This article continues a brief review of network startup on Mac OS X Server. It is intended to be a brief introduction to allow users to become more familiar with the boot process and how network operations are configured.
DISCUSSION Starting NIS Under normal operation, most users will not need to run Network Information System (NIS) because NetInfo will provide the same services. Both systems are distributed databases that contain network wide configuration information on users, passwords, hosts, groups, and so forth. Administrators can change this information from a server instead having to make changes for each machine on the network. NIS is not a supported component of the operating system. If the NISDOMAIN setting in /etc/hostconfig is set to YES (must be manually edited), then the computer will bind to the NIS server when /etc/startup/1100_DirectoryServices is executed. The computer will then be part of the NIS network and have access to that network's shared information. Starting NFS Network filesystem (NFS) is a way of sharing filesystems (directories) over networks. It provides transparent access to remote disks on the network. NFS uses RPCs to carry out the server-client relationship, so it is configured after RPC has already started. NFS is configured on the computer when /etc/startup/1500_NFS is executed. A computer running NFS can be a client, a server, or both. A server is a computer that is exporting filesystems, and a client is one that is importing filesystems. The server exports its filesystem by using nfsd and mountd while the client imports using the mount command. These commands are executed via the NFS script. The script imports directories using the mount -at nfs command. The -a flag tells mount to mount all available filesystems, and the -t nfs indicates that the filesystems should be of the nfs type. In Mac OS X Server, the filesystems are imported or exported using the File Sharing option in the HostManager.app. Starting AppleTalk AppleTalk is the proprietary property of Apple Computer and is often used to communicate over other networks. The Ethernet version is referred to as EtherTalk. AppleTalk is usually plug and play and much easier to configure than TCP/IP, but it may be more network intensive. The script 1300_AppleTalk starts the AppleTalk protocol on the computer. With this protocol active it is possible to print to AppleTalk printers, and to connect to AppleTalk computers. Starting TCP/IP TCP and IP are the two protocols that are at the heart of Unix-style networking. On all Unix-style systems these protocols are started with the inetd. This daemon is launched when the /etc/startup/1700_IPServices is executed. Inetd is considered a super-daemon because instead of having multiple daemons running for TCP/IP services, inetd starts them as requests are received. The clients contact inetd on well-known ports that are published in /etc/services . Once inetd has been contacted, it notifies the client on which port the connection will be taking place. The client then connects the server on that port. Inetd uses a one to one connection between servers and clients. This means that each time a new request comes in from a client inet starts up a new daemon. For example, when starting a new telnet session the client contacts inetd on port 23. Inetd then tells the client that the telnetd process has been start on port x (x is a variable meant to specify a higher, unreserved port.) This happens each time that a new telnet session is created. The total number of telnetd processes can be seen using the " ps -aux | grep telnetd " command. The total number of telnet connections can be seen with the " netstat | grep telnet " command. This command will display the port that each session is running on, and will allow the user to verify that the above is correct. (Telnetd is the daemon started by inetd to handle telnet sessions.) Starting Host Configuration Services If the server is configured to be a bootp of NetBoot server, bootpd and bootparamd will be launched when the /etc/startup/1700_IPServices script is run. These two daemons enable the computer to receive bootp requests when a client boots. This option can be turned on using the Setup Assistant, the Preferences.app, or by manually editing the /etc/hostconfig file. If a client is set to request an IP address at startup, it will broadcast its Ethernet address while /etc/startup/0800_Network is running. If the server is running and is on the same subnet, the server will respond to the broadcast with the client's IP address. Bootp packets can not cross a router unless the router is configured to allow this. This is one reason for NetInfo clones. The first part of this review of network startup can be found in the following article: Article 30757: " Mac OS X Server: Review Of Network Startup (1 of 2) " Starting AppleFileServer The Web administration services are started with the execution of 1600_AppleShare . This script launches the Web administration daemons and allows the AppleFileServer server to be configured with a web browser. |
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| Document Information | |
| Product Area: | Mac OS System Software |
| Category: | Mac OS X Server |
| Sub Category: | General Topics |
| Keywords: | kmosXserver |
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