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System Administration Guide: IP Services Oracle Solaris 11 Express 11/10 |
1. Planning an IPv4 Addressing Scheme (Tasks)
2. Planning an IPv6 Addressing Scheme (Overview)
3. Planning an IPv6 Network (Tasks)
4. Configuring TCP/IP Network Services and IPv4 Addressing (Tasks)
5. Enabling IPv6 on a Network (Tasks)
6. Administering a TCP/IP Network (Tasks)
8. Troubleshooting Network Problems (Tasks)
9. TCP/IP and IPv4 in Depth (Reference)
12. Planning for DHCP Service (Tasks)
13. Configuring the DHCP Service (Tasks)
14. Administering DHCP (Tasks)
15. Configuring and Administering the DHCP Client
Differences Between DHCPv4 and DHCPv6
How DHCP Client Protocols Manage Network Configuration Information
How the DHCPv4 Client Manages Network Configuration Information
How the DHCPv6 Client Manages Network Configuration Information
Enabling and Disabling a DHCP Client
ipadm Command Options Used With the DHCP Client
Setting DHCP Client Configuration Parameters
DHCP Client Systems With Multiple Network Interfaces
How to Enable a DHCPv4 Client to Request a Specific Host Name
DHCP Client Systems and Name Services
16. Troubleshooting DHCP (Reference)
17. DHCP Commands and Files (Reference)
18. IP Security Architecture (Overview)
20. IP Security Architecture (Reference)
21. Internet Key Exchange (Overview)
23. Internet Key Exchange (Reference)
24. IP Filter in Oracle Solaris (Overview)
Part IV Networking Performance
26. Integrated Load Balancer Overview
27. Configuration of Integrated Load Balancer Tasks
28. Virtual Router Redundancy Protocol (Overview)
29. VRRP Configuration (Tasks)
30. Implementing Congestion Control
Part V IP Quality of Service (IPQoS)
31. Introducing IPQoS (Overview)
32. Planning for an IPQoS-Enabled Network (Tasks)
33. Creating the IPQoS Configuration File (Tasks)
34. Starting and Maintaining IPQoS (Tasks)
35. Using Flow Accounting and Statistics Gathering (Tasks)
You can set up the DHCP client to run an executable program or script that can perform any action that is appropriate for the client system. The program or script, which is called an event script, is automatically executed after certain DHCP lease events occur. The event script can be used to run other commands, programs, or scripts in response to specific lease events. You must provide your own event script to use this feature.
The following event keywords are used by dhcpagent to signify DHCP lease events:
Description
The interface is configured for DHCP. The client receives the acknowledgement message (DHCPv4 ACK) or (DHCPv6 Reply) from the DHCP server, which grants the lease request for an IP address. The event script is invoked immediately after the interface is configured successfully.
The client successfully extends a lease. The event script is invoked immediately after the client receives the acknowledgement message from the DHCP server for the renew request.
The lease expires when the lease time is up. For DHCPv4, the event script is invoked immediately before the leased address is removed from the interface and the interface is marked as down. For DHCPv6, the event script is invoked just before the last remaining leased addresses are removed from the interface.
The client drops the lease to remove the interface from DHCP control. The event script is invoked immediately before the interface is removed from DHCP control.
The client relinquishes the IP address. The event script is invoked immediately before the client releases the address on the interface and sends the DHCPv4 RELEASE or DHCPv6 Release packet to the DHCP server.
An interface acquires new or updated configuration information from a DHCP server through the DHCPv4 INFORM or the DHCPv6 Information-Request message. These events occur when the DHCP client obtains only configuration parameters from the server and does not obtain an IP address lease.
During lease expiration, when one or more valid leases still remain, the event script is invoked just before expired addresses are removed. Those being removed are marked with the IFF_DEPRECATED flag.
With each of these events, dhcpagent invokes the following command:
/etc/dhcp/eventhook interface event
where interface is the interface that is using DHCP and event is one of the event keywords described previously. For example, when the ce0 interface is first configured for DHCP, the dhcpagent invokes the event script as follows:
/etc/dhcp/eventhook ce0 BOUND
To use the event script feature, you must do the following:
Name the executable file /etc/dhcp/eventhook.
Set the owner of the file to be root.
Set permissions to 755 (rwxr-xr-x).
Write the script or program to perform a sequence of actions in response to any of the documented events. Because Sun might add new events, the program must silently ignore any events that are not recognized or do not require action. For example, the program or script might write to a log file when the event is RELEASE, and ignore all other events.
Make the script or program noninteractive. Before the event script is invoked, stdin, stdout, and stderr are connected to /dev/null. To see the output or errors, you must redirect to a file.
The event script inherits its program environment from dhcpagent, and runs with root privileges. The script can use the dhcpinfo utility to obtain more information about the interface, if necessary. See the dhcpinfo(1) man page for more information.
The dhcpagent daemon waits for the event script to exit on all events. If the event script does not exit after 55 seconds, dhcpagent sends a SIGTERM signal to the script process. If the process still does not exit after three additional seconds, the daemon sends a SIGKILL signal to kill the process.
The dhcpagent(1M) man page includes one example of an event script.
Example 15-1 shows how to use a DHCP event script to keep the content of the /etc/resolv.conf file up to date. When the BOUND and EXTEND events occur, the script replaces the names of the domain server and name server. When the EXPIRE, DROP and RELEASE events occur, the script removes the names of the domain server and name server from the file.
Note - The example script assumes that DHCP is the authoritative source for the names of the domain server and the name server. The script also assumes that all interfaces under DHCP control return consistent and current information. These assumptions might not reflect conditions on your system.
Example 15-1 Event Script for Updating the /etc/resolv.conf File
#!/bin/ksh -p PATH=/bin:/sbin export PATH umask 0222 # Refresh the domain and name servers on /etc/resolv.conf insert () { dnsservers=`dhcpinfo -i $1 DNSserv` if [ -n "$dnsservers" ]; then # remove the old domain and name servers if [ -f /etc/resolv.conf ]; then rm -f /tmp/resolv.conf.$$ sed -e '/^domain/d' -e '/^nameserver/d' \ /etc/resolv.conf > /tmp/resolv.conf.$$ fi # add the new domain dnsdomain=`dhcpinfo -i $1 DNSdmain` if [ -n "$dnsdomain" ]; then echo "domain $dnsdomain" >> /tmp/resolv.conf.$$ fi # add new name servers for name in $dnsservers; do echo nameserver $name >> /tmp/resolv.conf.$$ done mv -f /tmp/resolv.conf.$$ /etc/resolv.conf fi } # Remove the domain and name servers from /etc/resolv.conf remove () { if [ -f /etc/resolv.conf ]; then rm -f /tmp/resolv.conf.$$ sed -e '/^domain/d' -e '/^nameserver/d' \ /etc/resolv.conf > /tmp/resolv.conf.$$ mv -f /tmp/resolv.conf.$$ /etc/resolv.conf fi } case $2 in BOUND | EXTEND) insert $1 exit 0 ;; EXPIRE | DROP | RELEASE) remove exit 0 ;; *) exit 0 ;; esac