Configuring Network Services and SSH Key Authentication on Linux
1. Gateway Server and Host Configuration
Set up gateway server with dual NICs: ens36: 12.0.0.254/24, ens33: 192.168.241.254/24. Server1 uses 192.168.241.0/24. PC1 and Server2 obtain IP via DHCP. Enable remote SSH access (e.g., Xshell) to Server1 and the gateway.
Adjusting Network Interfaces
On the gateway, disable firewall and SELinux:
systemctl stop firewalld
setenforce 0
On Server1:
hostname server1
bash # reload shell to apply hostname
systemctl stop firewalld
setenforce 0
On PC1:
hostname pc1
bash
systemctl stop firewalld
setenforce 0
Configuring NICs on Gateway
Copy the existing ens33 config to create ens36:
cd /etc/sysconfig/network-scripts/
cp ifcfg-ens33 ifcfg-ens36
Edit ifcfg-ens36 to set IP 12.0.0.254/24. Edit ifcfg-ens33 to set IP 192.168.241.254/24. Then restart network:
systemctl restart network
ip a
Configuring PC1's NIC
On PC1, edit /etc/sysconfig/network-scripts/ifcfg-ens33 to use DHCP, then restart network:
systemctl restart network
2. DHCP Server on Gateway
Install and configure DHCP to assign IPs to PC1 (192.168.241.x) and Server2 (12.0.0.x), including DNS server addresses.
Setting Up YUM Repository
cd /etc/yum.repos.d/
mkdir bak
mv *.repo bak/
vim local.repo
Add the following content:
[local]
name=local
baseurl=file:///mnt
gpgcheck=0
Mount the CD:
mount /dev/sr0 /mnt/
Install DHCP
yum install dhcp -y
Copy the sample configuration:
cp /usr/share/doc/dhcp-4.2.5/dhcpd.conf.example /etc/dhcp/dhcpd.conf
Edit /etc/dhcp/dhcpd.conf:
subnet 192.168.241.0 netmask 255.255.255.0 {
range 192.168.241.20 192.168.241.50;
option routers 192.168.241.254;
}
subnet 12.0.0.0 netmask 255.255.255.0 {
range 12.0.0.20 12.0.0.50;
option routers 12.0.0.254;
}
Start the DHCP service:
systemctl start dhcpd
On PC1/Server2, ensure their NICs are set to DHCP and restart network:
systemctl restart network
3. SSH Public Key Authentication
On Server1, generate an RSA key pair:
ssh-keygen
Leave passphrase empty when prompted.
Copy the public key to the gateway server:
ssh-copy-id -i .ssh/id_rsa.pub 192.168.241.254
Enter the root password of the gateway when prompted.
Test password-less login:
ssh 192.168.241.254
You should connect with out entering a password.
4. HTTPD with NFS Mount
Install and start Apache on Server1:
yum install httpd -y
systemctl start httpd
Initially, curl to localhost shows default page:
curl 192.168.241.254 # server1's own IP
Set Up NFS Export on Server2
On Server2, create a share directory and index.html:
mkdir /share
echo "Hello from NFS" > /share/index.html
Edit /etc/exports to export /share to all:
/share *(ro,sync)
Apply exports:
exportfs -r
exportfs -v
Start NFS service:
systemctl start nfs
Mount NFS to Apache Document Root
On Server1, check available NFS exports:
showmount -e 192.168.241.20 # Server2's IP
Mount the remote share:
mount 192.168.241.20:/share /var/www/html
Verify with df -h; you should see the NFS mount.
Test the web server:
curl 192.168.241.254
Output should display the content from the NFS-mounted index.html (e.g., "Hello from NFS").
