Preliminaries

Does the Client Have Existing Network(s)?

Winmachine Information Sheet

Setserv.pl

#!/usr/bin/perl -w
my($ip) = "192.168.106.3";
my($netmask) = "255.255.255.0";
my($oldip) = "192.168.105.3";

print "\n\n\n\nSETSERV\n";
#&checkit;
#exit;

system("hostname linuxhost");
system("ifconfig eth0 $ip netmask $netmask");
system("route del -net $ip");
system("route del -net $oldip");
system("route add -net $ip");
system("joe /etc/sysconfig/network");
system("joe /etc/sysconfig/network-scripts/ifcfg-eth0");
system("joe /etc/sysconfig/network-scripts/ifcfg-eth0:0");
system("rm /etc/sysconfig/network-scripts/ifcfg-eth0:0~");
system("joe /etc/resolv.conf");
system("joe /etc/hosts");
system("joe /etc/dhcpd.conf");
system("joe /etc/dhcpd.leases");
system("joe /etc/debug");
system("joe /etc/named.boot");
system("joe /etc/smb.conf");
system("joe /var/named/named.forward");
system("joe /var/named/named.reverse");
system("joe /etc/httpd/conf/httpd.conf");


&checkit;



sub checkit
 {
 system("find /var/named -type f | xargs grep -l $oldip > junk.named");
 system("find /etc -type f | xargs grep -l $oldip >> junk.etc");
 system("cat junk.named junk.etc | less");
 }

sub restartt
 {
 system("kill `cat /var/run/httpd.pid`");
 system("/etc/rc.d/init.d/httpd start");

 system("/etc/rc.d/init.d/named stop");
 system("/etc/rc.d/init.d/named start");

 system("/etc/rc.d/init.d/network stop");
 system("/etc/rc.d/init.d/network start");

 system("/etc/rc.d/init.d/sendmail stop");
 system("/etc/rc.d/init.d/sendmail start");


 }

•  /etc/sysconfig/network
• This allows editing of HOSTNAME, which should be the fully qualified machine dotted with the domain, the DOMAINNAME, the GATEWAY, which is the network (not host, network) ip address orred with 254. In fact only the GATEWAY ip number will normally be changed. A wrongly numberd GATEWAY will give a SIOACCART bad argument error on booting network.
• /etc/sysconfig/network-scripts/ifcfg-eth0
• The settings of interest here are IPADDR, NETMASK, NETWORK, and BROADCAST. : The IPADDR and NETWORK values will prevent pings even on the server. A bad NETWORK value will keep the network from loading.
• IPADDR= this is the host's ip address. It should be set to an unused ip number on the client's network. We default it to 192.168.100.3. Note that the ip address here should be wrapped in quotes.
• NETMASK="255.255.255.0" for class C, "255.255.0.0" for class B, etc. The class is determined by the netmask on the client's Windows machines. We default it to "255.255.255.0". Wrapped in quotes.
• NETWORK=This is the IPADDR anded with the NETMASK, both of which are described above. The default setting is "192.168.100.0".
• BROADCAST=This is the NETWORK described above, orred with 255. I'm not sure if this is correct, but it seems to work. Note that for some reason this value is NOT wrapped in quotes. Defaults to 192.168.100.255
• /etc/sysconfig/network-scripts/ifcfg-eth0:0
• This is where the eth0 interface's extra IP's are defined. These are used by /etc/httpd/conf/httpd.conf to determine virtual hosts. They must be in the same network as everything else. The one argument in this file is IPADDR="192.168.100.110-149", which is our configuration default. Note that for some reason, if the backup file /etc/sysconfig/network-scripts/ifcfg-eth0:0~ exists, it will create a second set of extra addresses. This is why setserv.pl deletes this file every time.
• /etc/resolv.conf
• This has the following two lines:
• domain mydomain.cxm
• nameserver 192.168.100.3
• No quotes on the IP. The number shown is our default. If this number is wrong it will screw up reverse DNS, which will hang amd, sendmail, and telnet. A good troubleshooting move is to rename the file until other problems are solved.
• /etc/hosts
• The line to modify in this file is:
• 192.168.100.3   linuxconf.mydomain.cxm  linuxconf
• The machine's IP address, followed by the fully qualified host/domain name followed by the hostname alone. Change the IP to reflect the host IP determined compatible with the client's existing Windows machines or networks.
• /etc/dhcpd.conf
• This configures dhcp, including the range of addresses available for leasing. It contains these three lines:
• subnet 192.168.100.0 netmask 255.255.255.0 {

    range 192.168.106.200 192.168.106.240;
    }
• The subnet is the network address compatible with the client's system, the netmask is the client's netmask, and the range must be legal addresses within the subnet. Note that if the client was previously using dhcp, and if you change anything here, you may need to manually expire the leases on each Win machine (ughh).
• To enable dhcp on the win98 machine, make sure network properties (tcp/ip protocol for network card) are set to obtain obtain an IP address automatically, and you "use dhcp for WINS resolution".
• /etc/dhcpd.leases
• This defaults to an empty file on our machines. Leave this alone and let DHCP fill it with leases.
• /etc/debug
• This has the host's IP address buried within the file. We haven't determined whether it's necessary for this to be accurate, but search for it (using the old or default ip, obviously), and change it to the host address found compatible with the client's machines.
• /etc/named.boot
• This is the beginning of the DNS system, defining where to find other DNS information. One line in here MUST be changed when you change the host address:
• primary         100.168.192.in-addr.arpa    named.reverse
• On a class B network (netmask 255.255.0.0) it will have only 2 numbers instead of the 3 it has for class C networks.
• Note the reverse notation of the network address. This is for reverse lookups. If this is not correct, reverse DNS won't work properly, causing amd, sendmail and telnet to hang, as well as nslookup (but nslookup can be unhung by renaming resolv.conf).
• joe /etc/smb.conf
• Samba configuration. This is where you match the client's "workgroup", in the workgroup variable in the [global] section. For instance, if the Windows workgroup is PENGUIN, then the line would look like this:
• workgroup = PENGUIN
• This file contains all user access to various directories, but anything besides the workgroup variable is beyond the scope of this document.
• /var/named/named.forward
• This is the forward DNS and is detailed in the DNS section of the 11/1998 Troubleshooting Professional Magazine tutorial (identified there as /var/named/named.mydomain.cxm). Use the joe editor's find/replace to change every IP in the document to something compatible with the client's network, the new host ip, and the alternate ip's for eth0 listed in /etc/sysconfig/network-scripts/ifcfg-eth0:0.
• BE SURE TO INCREASE THE SERIAL NUMBER (of form yyyymmdd##). If it isn't increased, changes to this file might not be recognized.
• /var/named/named.reverse
• This is the reverse DNS and is detailed in the DNS section of the 11/1998 Troubleshooting Professional Magazine tutorial (identified there as /var/named/named.192.168.100.3). Since all addressing in this file is relative to the 100.168.192.in-addr.arpa at the top, only the 100.168.192 must be changed to reflect the new network address.
• BE SURE TO INCREASE THE SERIAL NUMBER (of form yyyymmdd##). If it isn't increased, changes to this file might not be recognized.
• On a class B network (netmask 255.255.0.0) it will have only 2 numbers instead of the 3 it has for class C networks. It might work with 3, but amd will load very slowly, as will telnet.
• Any defects in this file can cause amd, sendmail and telnet to hang, as well as nslookup.
• /etc/httpd/conf/httpd.conf
• This is where virtual hosts are defined. Use the joe editor's search/replace to replace the old network part of ip addresses with the new network part.

Symptoms and Solutions:

Amd, sendmail, telnet and/or nslookup hangs or is (are) very slow

• /etc/resolv.conf. The domain and nameserver lines must be correct here or a reverse DNS problem occurs. Renaming this file can sometimes mask reverse DNS problems, expecially in the performance of nslookup, which can stop hanging after renaming /etc/resolv.conf. However, this rename DOES not solve the problem and is a coathanger at best. The nameserver line should have the fully qualified IP address of the server host you're installing. And of course, you will make that IP address compatible with the client's existing hardware.
• /etc/named.boot. The line

primary         100.168.192.in-addr.arpa    named.reverse
MUST accurately reflect the reverse-notation network address, not the host address. That means 3 numbers for class C, 2 for class B, 1 for class A.
• /var/named/named.reverse. The line

100.168.192.in-addr.arpa
must once again accurately reflect the reverse-notation network address, not the host address. That means 3 numbers for class C, 2 for class B, 1 for class A. It must match the number in /etc/named.boot.

How to Bust Into A Locked Up System

mount /dev/hda6 /mnt
cd /mnt/etc/rc.d/rc3.d
mv S72amd _S72amd
mv S80sendmail _S80sendmail
cd /
umount /mnt
exit

• The /etc directory might not be on hda6. Find whichever partition contains /etc.
• S72amd and S80sendmail might have different numbers on your system. Just be sure that any file beginning wth S and a number and ending with amd or sendmail is renamed so it starts with an underscore. This prevents it from being run at boot time.
• BE SURE TO REMEMBER to do the umount, or your work will not be retained. Note that you can't do a umount as long as you're in the /mnt tree.
• To learn more details about this, or to find how to create Linux boot and rescue disks, see the November 1998 Troubleshooting Professional Tutorial.

Troubleshooting