IRIX Advanced Site and Server Administration Guide

Chapter 15
Understanding Silicon Graphics' Networking Products

This chapter provides information about the standard hardware and software networking products provided with Silicon Graphics systems. It explains the physical connection of an IRIS system to an Ethernet and serial network and describes network hardware options and interface names for network devices. This chapter describes the standard networking files, directories, and daemons, and provides an overview of the network startup and shutdown processes. It also supplies a brief description of Silicon Graphic's optional networking products.

Topics covered in the remaining chapters of this guide require an understanding of the fundamentals of network theory and operation. If you need information on networking fundamentals, refer to the bibliography in the introduction to this guide for additional reading. Topics in this chapter include:

An overview of networking hardware. See "Networking Hardware".



An overview of networking software. See "Networking Software".



A list of optional networking software products. See "Optional Networking Products".



A look at the standard network configuration. See "Standard Software Configuration".



Starting and stopping your network. See "Network Startup and Shutdown".

Networking Hardware

The networking hardware that comes standard on every Silicon Graphics system is an Ethernet controller and 2 serial ports. (Some hardware products may have more ports than this, including an ISDN port.) The Ethernet controller may be an entire board or an integrated chip. Controllers interface between the networking software and the network medium.

To connect your Ethernet controller to a network, you must have this hardware:

an Attachment Unit Interface (AUI) cable, also referred to as a dropline or even simply as a cable



a transceiver



access to an active Ethernet cable

Figure 15-1 shows how systems (termed ``stations'' on the network) might be connected to an Ethernet network.

Figure 15-1 : Ethernet Network Attachment

The serial ports on an IRIS allows it to connect to serial networks. Serial line networks are systems connected by serial lines and modems. You do not need special hardware installed in your computer to connect to a serial network.

Figure 15-2 shows systems connected to a serial network using modems.

Figure 15-2 : Serial Line Network

Networking Hardware Options

In addition to Ethernet and serial-line hardware, other types of controllers can be installed in Silicon Graphics systems as options. Some optional hardware products are user installable, while others require installation by a System Support Engineer certified by Silicon Graphics.

Some optional networking hardware is listed below.

FDDIXPress



EFast



Token Ring



X.25 Option Board



Coaxial Emulator Optional



3270 Board



5080 Gateway



IRIS SNA Option Board

Controller Interface Names

The network controller is the physical board or chip. The interface is software's interpreter and handler of the controller. The interface name is the name most evident to the user. For example, network management tools refer to the interface name when providing information about the physical controller.

To configure a controller, each network controller on a system must have a valid interface name. A single system may have multiple controllers; each controller must have a unique interface name. Several different types of controllers are available. Each type has its own special interface name. Most network software supports a maximum of four network interfaces by default.

Some standard and optional interface names are listed in Table 15-1, where "*" is 0, 1, 2, or 3.

Networking Software

The standard networking software shipped with all IRIS systems adheres to the Internet Model standards and protocols. It is derived from the networking software in the 4.3BSD UNIX release from the University of California at Berkeley and the RPC (remote procedure call) system from Sun Microsystems. The IRIX® operating system implements the Internet Protocol suite and UNIX domain sockets using the 4.3BSD UNIX socket mechanism. The system also supports access to the underlying network media by means of raw sockets.

All standard networking software is supplied on the Execution Only Environment media (eoe1, eoe2, and netls_eoe). See Table 15-2 for a list of standard networking software for IRIS systems. See Table 15-3 for a list of the optional networking products for IRIS systems.

Optional Networking Products

Silicon Graphics Inc. supplies a variety of optional networking products, both hardware and software, to provide interconnectivity between various vendors and mediums. Table 15-3 lists and briefly describes some of the available optional networking products. See your sales representative for detailed product information.

Standard Software Configuration

The standard software configuration can be broken into two main categories:

Files and directories



Daemons

Note: See Chapter 21, "UUCP," for information regarding UUCP files, daemons, and tools. See Chapter 22, "SLIP and PPP," for information regarding SLIP files, daemons, and tools. NetLS and NCS are covered in the NetLS Administration Guide.

Files and Directories

Most of the standard software configuration files reside in /etc,/etc/config, and /etc/init.d. A brief description of each file is provided. Usage examples are provided throughout the guide where applicable. See the online reference page for more details.

The following are the network configuration files that reside in the /etc directory:

ethers(4)

This file is used by the Reverse Address Resolution Protocol (RARP) or bootp for mapping physical (MAC) addresses to logical (Internet) addresses. It must be built and maintained by the administrator. If this file is required, it should be updated when a system's network controller board is replaced. The applications discussed in this guide do not depend on the ethers file; however, other common network controllers, such as FDDI, are dependent upon this file.

hosts(4)

This file contains the Internet or logical address database. It is used by all network programs based on the Internet Protocol. There must be an Internet address for all systems with which this system communicates. The Network Information Service (NIS) and/or the Berkeley Internet Name Daemon (BIND), implementing the Domain Name System) can significantly impact the function of this file. See Chapter 16, "Planning a Network" for more details.

hosts.equiv(4)

This file contains a list of "trusted users," where trusted users can be system names or system and user names. Programs like rlogin, rcp, rdist, and rsh use this file to determine the amount of validity checking to be done. This file is used in conjunction with the /etc/passwd+ and .rhosts+ files.

networks(4)

This file contains the network name database. Administrators typically modify the file to contain information on local site networks (network addresses and names). The database is used by netstat(1M) to provide network number-to-names translation.

protocols(4)

This file contains the protocol name database. Specifically, it lists all known Internet Protocols by official name, number, and any aliases. This database is used by inetd to determine protocol support.

rpc(4)

This file lists all Remote Procedure Call (RPC) programs (portmapper, ypserv, mountd, etc.) and their respective program numbers. The rpcinfo(1M) and inetd(1M) programs use the information contained in this file.

services(4)

This file lists the ports associated with well-known (TCP/UDP). It is used by inetd to determine a server's port number. (RPC based applications get their port number assignments from the portmap program and /etc/rpc database.)

sys_id(4)

This file contains the system's host name. This file is accessed by various network applications to determine the identity of the system.

This list contains the standard networking configuration files located in the /etc directory:

inetd.conf

The configuration file used by the Internet super server, inetd, to determine which servers and daemons to start. You can modify this file to disallow access to various network services. See the inetd(1M) online reference page for additional information.

resolv.conf(4)

This file determines hostname-address resolution order. It can be used to override default system lookup services, such as the resolve order and the domain. This file must be configured on systems that want to be BIND or DNS clients. See the resolver(3N) and named(1M) online reference pages for additional information.

mrouted.conf

This is the configuration file for the mrouted daemon. Use this file to override the default multicast routing configuration. This file is also used to add multicast tunnel links between a local and remote network. See the mrouted(1M) online reference page for additional information.

ipfilterd.conf

This file contains the configuration information for the ipfilterd daemon. It contains macro and filter definitions. Some example macros are provided in the file. See the ipfilterd(1M) online reference page for additional information.

snmpd.auth

This file is used by the snmpd daemon to authenticate each incoming snmp request. It specifies get and set privileges for sets of systems and SNMP communities. The default configuration provides all systems from all communities with get privileges. See the snmpd(1M) online reference page for additional information.

gated.conf

Configuration file for the gated daemon. The configuration file can be used to configure gated to handle up to three routing protocols: Routing Information Protocol (RIP), Exterior Gateway Protocol (EGP), and HELLO. The default configuration supports RIP and HELLO. See the gated(1M) online reference page for additional information.

Daemons

There are three general network-related daemons that should always be running to support basic TCP/IP communications. Obviously, if you have optional network software loaded, other daemons are present. The general daemons are started by the master network configuration script, /etc/init.d/network, at boot time. All daemons are found in the /usr/etc directory. The three general network daemons are:

inetd(1M)

Also known as the super server. It listens for requests to certain network services. When it gets a request, it checks its configuration file, /etc/inetd.conf, to determine how and on which port to start the server. Three other files, /etc/services, /etc/rpc, and /etc/protocols are also addressed by inetd to get the appropriate port number and protocol information.

portmap(1M)

The daemon that converts RPC program numbers into TCP/UDP port numbers for Sun RPC. It must be running to support any RPC based network applications (NIS, NFS, rstatd, etc.). When inetd detects an RPC based connection, it contacts the portmap and gets the port number for the RPC connection. inetd starts the server on the port number supplied by the portmapper.

routed(1M)

Manages (adds, updates, deletes, propagates) the kernel routing tables on and between systems on a network. It is based on the Routing Information Protocol (RIP).

Other common network daemons are:

named(1M)

The Internet domain name server, also known as BIND. This daemon implements the Domain Name System (DNS). It loads the BIND database from the designated boot file, reads in the initial data, and listens and responds to host name or address queries. Site-dependent options and arguments reside in the /etc/config/named.options file.

mrouted(1M)

The Internet Protocol multicast routing daemon. mrouted forwards a multicast datagram to all networks reachable by a cooperating set of mrouted routers. If the intermediary routers do not support multicast routes, mrouted supports "tunnels," which provide a virtual point-to-point link between pairs of mrouted systems located anywhere on the network. mrouted runs on any interface capable of multicasting. To override the default configuration or to add tunnel links, modify the /etc/mrouted.conf file.

timed(1M)

The time server daemon. It averages a system's time with the time of other systems on a network running timed. It was designed for small and homogeneous networks. A timed master must be designated with a list of selected trusted systems (slaves) from which clock averaging is performed. One of the slaves serves as a backup if the master becomes unavailable. See /etc/config/timed.options to override defaults.

timeslave(1M)

The server daemon to slave a local clock to a common clock. timeslave is more efficient than timed. It consumes less network bandwidth, fewer CPU cycles, and less memory on both the local and remote systems. It was designed for large, heterogeneous networks and should be used in conjunction with timed. The /etc/config/timeslave.options file is not optional, it is required.

rarpd(1M)

The DARPA Reverse Address Resolution Protocol daemon. It responds to RARP requests. This daemon maps physical addresses (Ethernet) to logical addresses (Internet). For the rarpd daemon to answer requests, there must be a valid entry for the client in the server's /etc/hosts and /etc/ethers files. To override default configurations, see the file /etc/config/rarpd.options.

rwhod(1M)

The system status server. It maintains a database used by the rwho and ruptime applications. It must be running to support rwho and ruptime. Site-dependent options and arguments should go in the /etc/config/rwhod.options file. Do not run this daemon on a net with lots of systems; it could saturate the net. By default, rwhod is off.

gated(1M)

The gateway routing daemon that handles multiple routing protocols and replaces routed, egpup, and any other routing daemon that speaks the HELLO routing protocol. gated runs on the router that interfaces with an exterior router running HELLO. It handles the Routing Information Protocol (RIP), the Exterior Gateway Protocol (EGP), and HELLO. It can be configured to support any combination of the three protocols by modifying the /etc/gated.conf file. Default configuration supports RIP only.

rtnetd(1M)

The daemon that allows pre-emptable network packet processing. This daemon allows higher-priority real-time processes to preempt processing of incoming network packets, thus allowing better response for real-time processes. It should be run on multiprocessor systems for best throughput. To override defaults, see the /etc/config/rtnetd.options file.

snmpd(1M)

The daemon for the Simple Network Management Protocol (SNMP). snmpd, also called the SNMP agent, listens for SNMP services queries. Each SNMP request is checked for privileges in the file /etc/snmpd.auth.

Daemon Option Files

Site-dependent options for daemons are set in their respective configuration files in the directory /etc/config. Table 15-4 lists the required configuration flag, the daemon's function, and the options file. Consult the /etc/init.d/network script and each daemon's reference page for details.

Network Startup and Shutdown

The main network script is /etc/init.d/network. Other scripts for other network applications (UUCP, mail, etc.) also reside in this directory, but are covered in their appropriate chapter in this guide. A brief description of the network script is provided:

The network master script is called during system startup and shutdown. It defines the system name and host ID, ensures that the system has a valid Internet address, starts networking daemons, and initializes the network interfaces. Site-dependent configuration commands to start and stop local daemons, add static routes, and publish arp entries should be put in a separate shell script called /etc/init.d/network.local. Make symbolic links from /etc/rc0.d and /etc/rc2.d to /etc/init.d/network.local so the network.local file is called at system startup and shutdown (see "Creating a Local Network Script" for setup procedure).

The network master script is linked to /etc/rc0.d/K40network, which is invoked from /etc/rc0 during shutdown, and to /etc/rc2.d/S30network, which is invoked from /etc/rc2 during startup. The script understands two arguments: start and stop. It can be run manually for testing and troubleshooting network-related problems without having to reboot the system.

Network Initialization Process

During system initialization, the shell script /etc/init.d/network is called. These are the actions performed by the script at start up:

Checks host name and Internet address to determine if system should be configured as standalone or networked. Checks sys_id and hosts files. If the network configuration flag is off, the system is configured for standalone operation.



Determines names and addresses or primary and router interfaces for typical configurations.



Obtains any site-dependent information for interfaces from the netif.options file.



If system is not diskless, the shell script flushes all old routes.



Configures all interfaces, including loopback, using the ifconfig command.



If configured for IP packet filtering, the shell script starts the IP packet filtering daemon (/usr/etc/ipfilterd). The ipfiltered daemon must be started before gateway interface initialization.



Initializes gateway interface.



Initializes additional interfaces specified in the netif.options file.



If specified, initializes the Hypernet interface according to the ifconfig-hy.options file.



Initializes the loopback interface.



Using the chkconfig command, determines daemon configuration and reads relevant daemon configuration files (*.options).



Sets default route for all IP multicast packets to the primary interface.



If NIS software is configured, defines and sets NIS domain name.



If NIS software is configured, starts appropriate NIS daemons.



If NFS software is configured, starts appropriate NFS daemons and mounts any NFS file systems listed in the /etc/fstab.



If configured on with chkconfig, it starts standard daemons (inetd, timed, timeslave, rarpd, rwhod, snmpd, etc.).

Network Shutdown Process

During system shutdown, /etc/init.d/network stops the daemons and disables the network devices. These are the actions the script performs at system shutdown:

Kills all network services that may be associated with a shell (rlogind, rexecd, rshd, ftpd, telnetd, etc.).



Kills some network daemons immediately (inetd, bootp, tftpd, snmpd, etc.).



If NFS is running, unmounts remote file systems.



Kills all remote daemons.



If NFS is running, unexports exported file systems. See the NFS Administration Guide and the NIS Administration Guide for complete information about the optional NFS software.



Kills daemons that must be kept alive until the last minute (portmap, slip, ipfiltered)



Gracefully takes the system off the FDDI ring, if it is on the ring.



Stops the ypbind process of NIS.

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