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Whitehatters Computer Security Club: Blueside

Organized by Jordan Bermudez

Outward facing network inbetween trusted internal network (LAN) and untrusted external network such as the internet
Segregated from personal files
Typically containing devices accessible to internet traffic, such as Web and DNS servers

Install Ubuntu
Change network options to Host-Only, DMZ
Type in ip link show into terminal and you should see: lo, enp0s3
- ip link show : shows information for all interfaces
- lo : loopback
- enp0s3 : virtual network driver
Add another interface
- type sudo nano /etc/network/interfaces to edit the network interfaces configuration file with console based text editor nano
- add
```
  auto enp0s3
  iface enp0s3 inet static
  address 172.20.240.23
  netmask 255.255.255.0
  gateway 172.20.240.254
  dns-nameservers 8.8.8.8
```
- type sudo service networking restart
- verify netowrk interfaces with ifconfig
- verify connectivity with ping 8.8.8.8
  - 8.8.8.8 is google’s DNS server

Server maintaining a directory of domain names and translate them to IP addresses
- www.google.com -> 201.23.52.1
- 201.23.52.1 -> www.google.com
Internet Service Providers view DNS servers to translate a web address you type into an IP address
DNS Zone: a set of DNS records for a single domain
DNS Record : single entry of instructions on handling requests based on types for a zone
- A Record : Specifies IPv4 Address for a given host
  - www.google.com -> 201.23.52.1
- AAAA Record (quad-A record): specifies IPv6 address for given host
  - www.google.com -> 2001:db8::7348
- CNAME Record: specifies a domain name that has to be queried in order to resolve the original DNS query
  - also used to create aliases of domain names
  - same server can be accessesed through documents.example.com and docs.example.com because of CNAME
- MX Record: specifies a mail exchange server for a DNS domain name
  - the information is used by Simple Mail Transfer Protocol (SMTP) to route emails to proper hosts
- PTR Record: (reverse of A and AAAA DNS Records) used to look up domain names based on IP addresses

Helpful link for configuration process
Helpful link for understanding bind
Update and install bind
- sudo apt-get update
- sudo apt-get upgrade
- sudo apt-get install bind9 bind9utils bind9doc
- bind is a widely used domain name system software for your server to become a DNS for your network
Configure caching name server
- sudo nano /etc/bind/named.conf.options
- uncomment and change the lines
```
  //forwarders {
  //	0.0.0.0;
  //};
```
  to
```
  forwarders {
  8.8.8.8;
  8.8.4.4;
  };
```

Change dns-nameservers so that bind will handle it

change to

  auto enp0s3
  iface enp0s3 inet static
  address 172.20.240.23
  netmask 255.255.255.0
  gateway 172.20.240.254
  dns-nameservers 172.0.0.1

Refresh
- sudo ip addr flush enp0s3
  - ip addr flush removes all addresses for the interface enp0s3
- sudo systemctl restart networking.service
  - systemctl is the system manager
  - restart networking.service will restart the networking service that systemctl manages
- sudo systemctl restart bind9
  - will restart bind9
- ping www.google.com
  - verify internet connection
Creating zones
- sudo nano /etc/bind/named.conf.local
- add ``` zone “wcsc.com” { type master; file “/etc/bind/forward.wcsc.com”; allow-transfer { 172.20.241.27; }; also-notify { 172.20.241.27; }; };
zone “20.172.in-addr.arpa” { type master; file “/etc/bind/reverse.wcsc.com”; allow-transfer { 172.20.241.27; }; also-notify { 172.20.241.27; }; }; ```
- create the zone files mentioned in the configuration
  - sudo touch /etc/bind/forward.wcsc.com
  - sudo touch /etc/bind/forward.wcsc.com
- add zone content
  - add lines sudo nano /etc/bind/forward.wcsc.com
  - add lines sudo nano /etc/bind/reverse.wcsc.com
- Troubleshooting
  - sudo named-checkconf /etc/bind/named.conf will output the errors for fixing
Verify
- sudo systemctl restart bind9
- verify with nslookup 172.20.240.11
  - (in this case) nslookup is used as a command to print the name and requested information for a domain (or host) nslookup 172.20.240.23 nslookup WEB.wcsc.com nslookup DNS.wcsc.com ping WEB.wcsc.com