In this video, I show you how to setup a DHCP server on a CentOS 7 Linux Machine. This is the start of having a computer, running CentOS 7, to be your router and gateway to the internet. This is the first video, and we just touch on getting the DHCP rolling.
If you use debian or anything debian based, I cannot help you. Do not ask for help on those distributions. There are other video resources available. Keep in mind, most of what I do here can be done on those distributions anyway. File locations may vary.
Text version: https://www.bromosapien.net/media/index.php/Linux_Router_and_Firewall
-Two Network cards (One can be built in, and the other can be PCI or PCIe)
You can follow along completely if you use these distributions:
Commands to note:
vi -- It's an editor in linux. i for insert, o for a new line, shift+g to go to the end of the file, ESC for command mode. :wq saves your file (zz does too).
systemctl restart name --name being the name of the service
yum install name ---name being the name of the package
systemctl enable/disable -- disables or enables services
Files/Folders to note:
IP Scheme format:
10, 172, 192 are private IP's. Use them. Trust me.
ens192 is the modem
ens224 is the network
Dropping pings: -A INPUT -i enp3s0 -p icmp -m icmp --icmp-type 8 -j DROP
To make sure it works, you may want to isolate your linux box from the network, hook up a cross-over cable between a laptop and your linux box and see if you can get an IP. This is the best way, in my opinion, to make sure DHCP is working properly.
** RHEL 7/CentOS 7 names their network interfaces based on the hardware. This can be changed using biosdevname=0 and net.ifnames=0 on the kernel line at install time. You can also use this when the system is up and ready. You are free to rename the interfaces using udev rules.
1. I know my syntax is correct, I have no mistakes, but I cannot get DHCPD to start. It always fails!
A. You may have to start all the way over. However, you may want to check for missing semicolons. Typically systemctl status dhcpd -l will tell you what's going on.
2. My computers are not getting IP's set up from my box, what do I do?
A. Make sure your stock router is not issuing its own DHCP. The best way to do this, is to log into your router (usually 192.168.0.1). Admin being the username and password being the password by default. Some are admin/admin. Read your documentation for more details. You may ALSO want to give the router an IP address so you can still access it later... it needs to match the scheme you setup. Example of my scheme: 10.100.2.20 :: It's outside my 100-254 range, so it's easy for me to remember.
3. I can ping my own IP given to me from my provider, so this means I'm not secured?
A. No, just because you can ping yourself, doesn't mean you're not secure. You're just pinging that modem, pretty much, if you want to think of it that way.
4. Will you ever make a written tutorial for this? I enjoy the visual and explanations, but a written tutorial would be nice too.
A. Yes, there is one available at the top of the description.