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This is a copy protection daemon that is specific to the Santa Cruz Operation versions of TCP/IP. When TCP/IP starts, it registers with the copy protection daemon. When the cpd receives a datagram from a remote system with the same serial number, a warning message is printed advising the system administrator of the problem. SCO is the only system with this feature.
The lpd is the line printer daemon, or spool area handler, and is executed at boot time. It accepts incoming print jobs on a specific TCP/IP port, and queues the print job for printing on the local or remote system. The printer configuration information is stored in the file /etc/printcap, and the access control to the printer is maintained through the file /etc/hosts.lpd.
The SNMP daemon is an implementation of the Internet Simple Network Management Protocol, as defined in RFCs 1155-1157, 1213, and 1227. While this daemon is capable of receiving information from SNMP agents on other systems, many systems do not include SNMP Management software.
The RARP command is a daemon that responds to Reverse Address Resolution Protocol (RARP) requests. Other systems typically use RARP at boot time to discover their (32 bit) IP address given their (48 bit) Ethernet address. The booting machine sends its Ethernet address in an RARP request message. For the request to be answered, the system running rarpd must have the machine’s name-to-IP-address entry in the /etc/hosts file or must be available from the domain name server and its name-to-Ethernet-address entry must exist in the /etc/ethers file. Using the above two sources, rarpd maps this Ethernet address into the corresponding IP address.
The BOOTP daemon implements an Internet Boot Protocol server as defined in RFC 951 and RFC 1048. The bootpd daemon is started by the inetd super-server when a boot request arrives. If bootpd does not receive another boot request within 15 minutes of the last one it received, it exits to conserve system resources. The Internet Boot Protocol server is designed to provide network information to the client. This information can include, but is not restricted to, the client’s IP address, netmask, broadcast address, domain server address, router address, etc.
The routed daemon is invoked at boot time to manage the Internet Routing Tables. The routed daemon uses a variant of the Xerox NS Routing Information Protocol to maintain up-to-date kernel Routing Table entries. In normal operation, routed listens on the UDP socket 520 to provide the route service for routing information packets. If the host is an internetwork router, it periodically supplies copies of its routing tables to any directly connected hosts and networks.
The netstat command, which is discussed later in this chapter, is used to print the routing tables on a host. The netstat command is shown following:
$ netstat -r Routing tables Destination Gateway Flags Refs Use Interface nb.ottawa.uunet. gateway UH 0 1 du0 localhost.0.0.12 localhost.0.0.127. UH 3 0 lo0 topgun gateway UH 1 3218 du1 default gateway UG 1 669360 du0 Lab.widgets.ca gateway U 8 3340413 wdn0 Ottawa.widgets.ca gateway U 10 2083505 iat0 $
The list identifies the gateway that is used to reach a specific destination network, along with the status of the route (flags). It also includes how many connections are in use through that gateway, the number of packets through the gateway, and the name of the interface in this machine that connects the machine to the network.
Most systems are capable of handling dynamic and static routes. The dynamic routes are handled by the routed daemon. As the routes change, the routed daemon updates the tables and informs other hosts as needed. The static routes generally are manipulated by hand using the route command, and generally are not controlled by the routed daemon.
named is the Internet Domain Name Server, and it is the second mechanism available to provide hostname to IP address resolution. The daemon can serve in a variety of roles, including primary, secondary, caching, and as a slave, depending upon the requirements of the network administrator. If the /etc/hosts file is not used, and domain name service (DNS) is configured, then the system makes requests to the DNS to provide the IP address for a hostname. If the local DNS does not know the IP address for the specified host, it queries other name servers until it obtains the address.
The user command nslookup is used to query the DNS server for a given piece of information. The following illustrates using the nslookup command to find the IP address for the hostname gatekeeper.dec.com.
$ nslookup gatekeeper.dec.com Server: gateway.widgets.ca Address: 192.139.234.50 Non-authoritative answer: Name: gatekeeper.dec.com Address: 16.1.0.2 $
In this output, the domain name server gateway.widgets.ca cannot provide an authoritative response because it is not the authoritative master for the dec.com domain. The end result is that you learn the IP address for gatekeeper.dec.com is, in fact, 16.1.0.2.
This daemon is responsible for logging various system messages in a set of files described by the syslogd configuration file /etc/syslog.conf. Each message is saved on a single line in the file and can contain a wide variety of information. The syslog daemon receives information sent to it and saves the messages in its log file. Information can consist of informational, error, status, and debug messages. Each message also can have a level of severity associated with it.
The inetd super-server listens on multiple TCP/IP ports for incoming connection requests. When the request is received, it spawns the appropriate server. The use of a super-server enables other servers to spawn only when needed, thereby saving system resources. When the connection is terminated, the spawned server terminates.
Typically, servers that are started through inetd include fingerd, ftpd, rexecd, rlogind, and others. inetd, however, cannot be used for servers like named, routed, rwhod, sendmail, or any RFS or NFS server.
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