Configure Dhcp In Solaris

Intro. This document provides a simple guide to configuring a Solaris system as a DHCP server using the software supplied with the operating system. The command line interface is used thoughout, no reference made to the Sun's GUI tool 'dhcpmgr'. This procedure was performed on a Solaris 9 system, though it is likely also applicable to Solaris 7 & 8. The dhcp server setup here serves a single network, makes no effort to register names in any naming service, and does not enable BOOTP.

Packages You should have the 3 basic DHCP packages installed; # pkginfo | grep system SUNWdhcsb system SUNWdhcsr system SUNWdhcsu

DHCP Binary File Format Data Module for BOOTP/DHCP Services BOOTP/DHCP Server Services, (Root) BOOTP/DHCP Server Services, (Usr)

Procedure 1. 2. 3. 4. 5.

Create basic DHCP configuration and dhcptab files Create a macro for the local network Create the local network table Add some entries to the network table Start the DHCP server

1. Basic DHCP Configuration Use dhcpconfig to setup dhcpsvc.conf and dhcptab, here we simply define the type of datastore (SUNWfiles = text files) and the location of datafiles; # dhcpconfig -D -r SUNWfiles -p /var/dhcp

2. Create a macro for the local network Here we create a macro for our local network ( the one we will serve IP addresses for) in dhcptab # dhtadm -A -m 192.9.200.0 -d ':Broadcst=192.9.200.255:Subnet=255.255.255.0:MTU=1500:'

3. Create the local network table

# pntadm -C 192.9.200.0

4. Add some entries to the network table Here we define three local IP address that will be leased out by the dhcp server... # pntadm -r SUNWfiles -p /var/dhcp -A 192.9.200.201 192.9.200.0 # pntadm -r SUNWfiles -p /var/dhcp -A 192.9.200.202 192.9.200.0 # pntadm -r SUNWfiles -p /var/dhcp -A 192.9.200.203 192.9.200.0

5. Start the DHCP server Use the standard init.d boot script and watch /var/adm/messages for problems; # sh /etc/init.d/dhcp start

If you have problems stop the daemon and run it manually with the debug & verbose options; # /usr/lib/inet/in.dhcpd -dv 3fe143d6: Daemon Version: 3.5 3fe143d6: Maximum relay hops: 4 3fe143d6: Run mode is: DHCP Server Mode. 3fe143d6: Datastore resource: SUNWfiles

What is DHCP? DHCP is used to automatically configure network parameters on client workstations. Whilst it can be used to configure any and every known network parameter it is typically used simply to automatically allocate IP addresses and deliver static information such as the addresses of network routers and DNS servers. DHCP client support is present in most modern operating systems - include MS Windows, Linux, Solaris, HP-UX etc.

Introduction One of the problems that can arise when trying to use a Solaris box as a DHCP  client is that by default, the server is expected to supply a hostname, in addition  to all the other stuff (like IP address, DNS servers, etc.). Most cable modems and  home routers don't supply a (usable) hostname, so it gets set to "unknown". This  page describes how to get around that. (Where this page says "cable modem",  "DSL modem" can be substituted.) 

This page assumes that le0 is the interface you using for your DHCP connection.  Substitute hme0 or whatever interface you're actually using in the examples below. 

Setting up DHCP There are two ways of using DHCP:  • •

DHCP has limited control  DHCP has full control 

The first case may be where you want to use your own /etc/resolv.conf and so  on, with a minimum of hassle.  The second case would be the normal situation, especially if your cable modem  provider has a habit of changing DNS name server IP addresses on you (like  mine does!), so I'll concentrate on that here. I have a script to automate the first  method, should you want to use it. You'll need to change the DEFAULT_ADDR and  INTERFACE variables as required.  The first thing to do is to create an empty /etc/hostname.le0, like this:     > /etc/hostname.le0 Creating this file ensures that the interface gets plumbed, ready for the DHCP  software to do its stuff.  Next, you create /etc/dhcp.le0. This file can be empty if you want to accept the  defaults, but may also contain one or both of these directives:  •

wait time, and 

•

primary 

By default, ifconfig will wait 30 seconds for the DHCP server to respond (after  which time, the boot will continue, while the interface gets configured in the  background). Specifying the wait directive tells ifconfig not to return until the  DHCP has responded. time can be set to the special value of forever, with  obvious meaning. I use a time value of 300, which seems to be long enough for  my cable provider. 

The primary directive indicates to ifconfig that the current interface is the  primary one, if you have more than one interface under DHCP control. If you only  have one interface under DHCP control, then it is automatically the primary one,  so primary is redundant (although it's permissible).  With these files in place, subsequent reboots will place le0 under DHCP control:  you're ready to go! 

Unknown hostname Actually, there's one snag: most (if not all) cable modem DHCP servers don't  provide you with a hostname (even if they did, odds are it won't be one you want  anyway!). This wouldn't be a problem, except that the boot scripts  (/etc/init.d/rootusr in particular) try to be clever, and set your hostname to  "unknown" in this case, which is not at all useful!  The trick is to change your hostname back to the right one, preferably without  changing any of the supplied start­up scripts, which are liable to be being  stomped on when you upgrade or install a patch. You've also got to do it early  enough in the boot process, so that rpcbind, sendmail and friends don't get  confused by using the wrong hostname. To solve this problem, put this little script  in to /etc/init.d/set_hostname, with a symbolic link to it from  /etc/rc2.d/S70set_hostname.  Starting with Solaris 10, the preceding paragraph can be ignored. Instead, just  make sure that the hostname you want to use is in /etc/nodename; the contents  of that file will then be used to set the hostname. (Note that it is essential that the  hostname you put into /etc/nodename is terminated with a carriage return.  Breakage will happen if this is not the case.) Also, from Solaris 8 it is possible to  tell the DHCP software not to request a hostname from the DHCP server. To do  this, remove the token 12 from the PARAM_REQUEST_LIST line in  /etc/default/dhcpagent. (/etc/default/dhcpagent describes what the default  tokens are; 12 is the hostname, 3 is the default router, 6 is the DNS server, and  so on.)  With these modifications in place, reboot, and you'll be using your cable modem  in no time! 

If you've got more than one machine, and you want to access the Internet from all  of them, you might also find my Solaris NAT page useful.  If this page has been useful to you, please consider buying a copy of my book,  Solaris Systems Programming.