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1. | Your internal network is growing, and you're having trouble keeping up with the different workstations that are being added to your network on a regular basis. You use the good.example.com subdomain for your internal network, and you've named your computers for your departments, such as engr1 through engr10.good.example.com. Your mail server is named postal, your Web server is named www, your FTP server is named ftp. You want to configure a DNS server on the computer named names. What do you need to do? While you may not have enough information in this lab to create a complete and working file, you should be able to figure the outline of what you need to do, with the possible exception of specific IP addresses. |
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1. | While you could subcontract out the task to an ISP, it's easy to create a DNS server for your internal network. The basic files are already available on RHEL 3. All you need to do is modify these files and add appropriate zone files to your /var/named directory. As there are problems with the Red Hat DNS Server Configuration tool, I'll describe the basics on how you can set up a DNS server by directly editing the appropriate configuration files. Assume that you're using the 10.11.12.0/255.255.255.0 network addresses for your LAN. First, you'll need to modify the default /etc/named.conf configuration file. It's best to start by backing up this file. You'll need to add stanzas that refer to a zone and a reverse zone file. The stanzas are straightforward: zone "good.example.com" IN { type master; file "good.example.com.zone"; }; zone "12.11.10.in-addr.apra" IN { type master; file "good.example.com.rr.zone"; allow-update { none; } }; Next, you can create the good.example.com.zone and good.example.com.rr.zone files in the /var/named directory. These files will contain a database of local and reverse local computer names and IP addresses for your LAN. In the good.example.com.zone file, you'll want to create the forward database for your DNS server. It'll contain the records for your domain as well as the administrator e-mail address. There's not enough information in the problem to set up a full file, but the following principles apply. You need to start the zone file with a general Time To Live (TTL) variable; for example, the following command sets a standard TTL (4 days) for data on this DNS server: $TTL 4D You'll need a Start Of Authority (SOA) record with the name of the DNS server and your administrative e-mail address. The format of the e-mail address is a little strange; the following line sets an e-mail address of admin@good.example.com. It also sets a serial number based on the date, a refresh (16 hours) and a retry frequency (4 hours), an expatriation period (2 weeks), as well as a TTL (4 days). Do note the dot at the end of each name:
@ IN SOA names.good.example.com. admin.good.example.com. ( 200402121 16H 4H 2W 4D Now you can specify the computers associated with the DNS and mail servers: IN NS names.good.example.com. IN MX 10 postal.good.example.com. Finally, you can specify the different computers on your network. While no specific IP addresses are given, you know that you have computers with the following names that you'll have in the good.example.com.zone file. I've added arbitrary IP addresses on the given IPv4 network. You'll have to find the proper IP addresses for yourself with ifconfig commands on each computer: engr1 IN A 10.11.12.1 engr2 IN A 10.11.12.2 engr3 IN A 10.11.12.3 engr4 IN A 10.11.12.4 engr5 IN A 10.11.12.5 engr6 IN A 10.11.12.6 engr7 IN A 10.11.12.7 engr8 IN A 10.11.12.8 engr9 IN A 10.11.12.9 engr10 IN A 10.11.12.10 ftp IN A 10.11.12.11 www IN A 10.11.12.12 postal IN A 10.11.12.13 Finally, to make sure that the DNS server works the next time you boot this Linux computer, you'll want to set it to run at the appropriate runlevels with a command such as the following: # chkconfig --level 35 named on |
2. | You'll need two Linux computers for this lab: one as an NFS server, a second as an NFS client. Let's call these computers nfssvr.example.com and nfsclient.example.com. On the server, you'll want to share the /home directories, and provide write permissions to the client computer. On the client, you'll want to set up the /home directory from the NFS server to be mounted the next time you boot that client computer. |
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2. | This lab is the first step towards creating a single /home directory for your network. Once you get it working on a single client/server combination, you can set it up on all clients and servers. You can then use the NIS server described in Chapter 10 for a single Linux/Unix database of usernames and passwords for your network. On the NFS server, you'll want to take the following steps:
Now on the NFS client, you'll want to take the following steps to connect to the shared /home directory:
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3. | You'll also need two Linux computers for this lab: one as a DHCP server, a second as a DHCP client. Using the DHCP server created earlier in this chapter, set up a static IP address for the computer of your choice. You'll want to assign a specific name for that server, precious.example.com, and a special IP address on the 10.11.12.0 network, 10.11.12.13. Assume that you've already set up the example.com network as well as an appropriately configured DNS server. |
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3. | Assuming you've read the chapter, you've seen the template in the dhcpd.conf.sample configuration file for a static IP address: host ns { next-server marvin.redhat.com hardware ethernet 12:34:56:78:AB:CD; fixed-address 207.175.42.254; } As described in the chapter, the next-server command is associated with the boot server for this computer; since there is no boot server mentioned, you won't need this command. To set up the DHCP server, take the following steps:
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4. | Your network has more than 500 hosts with users in three major groups wanting to share their files within their groups. There are also 30 Windows XP clients in the publishing department that cannot use the Linux OS for their proprietary software needs. Everything is time-critical, as the outputs are related to stock quotes and therefore need to be synchronized to the same clock. What should you do? |
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4. | You need to configure a few services on your central host. NIS can be used to manage all the users so that all hosts use the same user IDs. Then configure a central server with Samba and NFS and sufficient disk space for the four groups, restricting each service to members of each group only. Use NTP to synchronize the NFS server to an Internet time server, if available, and then have all the other hosts synchronize their time to the NFS server host on an hourly basis. As NIS is covered in the next chapter, I don't go into additional detail here. |
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