Lab 004: Linux Network Services
# 1. SSH into the jump server, App server 1, App server 2, and App server 3 and switch
# to root. Check if the httpd is working in all App servers.
# 2. One of the App Servers has an issue with the HTTPD. Check what might be wrong on the configuration
# or the App Server. In this case, check the processes.
# 3. Check the iptables as well and ensure that traffic to the specified port is allowed.
# Append rules and make sure it is placed at the top of iptables. Save the iptables.
# 4. From jump server, try to telnet onto the App Server 1.
# Also try to curl.
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III. STEPS - BREAKDOWN
# 1. SSH into the jump server, App server 1, App server 2, and App server 3 and switch
# to root.
sudo su -
******
sshpass -p '******' ssh -o StrictHostKeyChecking=no tony@172.16.238.10
sudo su -
******
sshpass -p '******' ssh -o StrictHostKeyChecking=no steve@172.16.238.11
sudo su -
******
sshpass -p '******' ssh -o StrictHostKeyChecking=no banner@172.16.238.12
sudo su -
******
# 2. One of the App Servers has an issue with the HTTPD. Check what might be wrong on the configuration
# or the App Server. In this case, check the processes.
systemctl enable httpd # Apache is functioning in the App servers except App Server 1
systemctl start httpd
systemctl status httpd
# Check the processes using netstat. Here we can see that a process is using the Apache port specified - 5003
# Kill the process and then restart and verify status of httd. It should be working now.
netstat -tulpn
netstat -tulpn | grep 5003
sudo kill -9 291
systemctl enable httpd
systemctl start httpd
systemctl status httpd
# 3. Check the iptables as well and ensure that traffic to the specified port is allowed.
# Append rules and make sure it is placed at the top of iptables. Save the iptables.
iptables -L
iptables -L INPUT -nv
iptables -I INPUT -p tcp --destination-port 5003 -j ACCEPT
service iptables save
systemctl enable iptables
systemctl start iptables
systemctl status iptables
# 4. From jump server, try to telnet onto the App Server 1.
# Also try to curl.
telnet stapp01 5003
telnet 172.16.238.10 5003
curl stapp01:5003
# ENOTE:
# Now I actually spent a chunk of time on the last part where I need to telnet from the jump server
# onto the App server 1.
# I was already able to curl the App server 1 from the jump host but I just can't seem to
# establish a telnet connection.
# I've gone over all the KKC articles about this specific lab and I have followed every steps that
# are suggested in thos articles but I still can't telnet from the jumphost onto the App server 1.
# At last, I told myself and hoped that this should perhaps be a backend issue on the KK's end
# and just hit finish.
# "SUCCESS"
# Although it shows success and I gained the experience points for this lab,
# I still can't shake the feeling that I must have done somethign wrong on the config because
# I was not able to telnet.
# Well, what the heck.
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