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NETWORK CONFIGURATION
SERVER CONFIGURATION
Mail server configuration
Required Information
1.Determine the machines IP address.
2. Network mask. This determines which portion of the IP address specifies the subnetwork number and which portion specifies the host. Class C (most networks) 255.255.255.0
Class B 255.255.0.0
3. Network address : which is IP address bit wise anded with the network mask.Ex: IP: 192.168.1.100Mask: 255.255.255.0Net Addr:: 192.168.1.0
Required Information
4. Broadcast address. Used to broadcast packets to every machine on a subnet. Ex: IP: 192.168.1.100Mask: 255.255.255.0Net Addr: 192.168.1.255
5. Gateway address. The address of the machine that is your gateway to the outside world.
In many cases: Ex: IP: 192.168.1.100 Gateway: 192.168.1.1
6. Nameserver address. Translates host names into IP addresses. 192.168.1.10
Configuration tools
Netconf: A GUI interactive interface available on Red hat 6.1
netconfig: A GUI step by step interface
ifconfig: A text based program to configure the network interface.
program
/etc/sysconfig/network - Defines network and some of its characteristics.
/etc/HOSTNAME - Shows the host name of this host. If name is "myhost" then that is exactly the text this file will contain.
/etc/resolv.conf - Specifies the domain to be searched for host names to connect to, the nameserver address, and the search order for the nameservers.
/etc/host.conf - Specifies the order nameservice looks to resolve names./etc/hosts - Shows addresses and names of local hosts.
program
/etc/networks - Provides a database of network names with network addresses similar to the /etc/hosts file.
/etc/sysconfig/network-scripts/ifcfg-eth* - There is a file for each network interface. This file contains the IP address of the interface and many other setup variables.
Analysis Tools
netstat - Displays information about the systems network connections, including port connections, routing tables, and more. The command "netstar -r" will display the routing table.
traceroute - This command can be used to determine the network route from a computer to some other computer on a network or the internet. To use it can type "route IPaddress" of the computer.
Analysis Tools
nslookup - Used to query DNS servers for information about hosts.
tcpdump - This program allows the user to see TCP traffic on their network.
Manual Configuration
To use networking on any permanent basis
1.setup the file /etc/sysconfig/network
2.Assign an ip address with "ifconfig eth0 192.168.1.100 netmask 255.255.255.0 up".
3.Tell machine that a hub is ready for information with the command "route add -net 192.168.0.0 netmask 255.255.255.0 eth0“.
Manual Configuration
4.To contact hosts outside of a network ,
if a machine with IP address 192.168.1.1 is the gateway use the command "route add default gw 192.168.1.1 eth0“.
5.If using a dialup connection use the command "route add default ppp0" The word default says if the packet is not for a machine on your local network, send it to the default device.
Configuring an interface for multiple IP addresses
To configure a network card to act as more than one IP address, issue the following command: ifconfig dummy 192.168.1.102 netmask 255.255.255.0
To disable this, issue the following command.
ifconfig dummy down.
SERVER CONFIGURATION
MAIL SERVER CONFIGURATION
Mail Server Setup
Mail Architecture
Sendmail Configuration
Daemon: sendmail
Configuration File: /etc/mail/sendmail.mc
Edit the following lines
LOCAL_DOMAIN(`localhost.localdomain')dnl
DAEMON_OPTIONS(`Port=smtp,Addr=127.0.0.1, Name=MTA')dnl
Run “make –C /etc/mail” command to compile sendmail.mc and generate sendmail.cf file.
Restart sendmail and watch for errors