How can we get the Apache instance in a private subnet to work?
Configuration
Public subnet with 1 NAT instance
Private subnet with 1 App instance
Details
1. Masquerading is turned on NAT on via
iptables -t nat -A POSTROUTING -j MASQUERADE
2. PREROUTING is enabled via
iptables -t nat -A PREROUTING -p tcp --port 80 -j DNAT --to-destination 10.0.10.102:80
3. Port forwarding is enabled in /proc/sys/net/ipv4/ip_forward
4. Security group for both NAT & App (Would never keep these in production but
purely to show all ports are open)
Inbound All Traffic 0.0.0.0/0
Outbound All Traffic 0.0.0.0/0
5. Network ACLs
Inbound All Ports 0.0.0.0/0
Outbound All Ports 0.0.0.0/0
6. Ping & wget work for external requests
ping google.com
wget google.com
7. Apache is listening on the App instance in the private subnet.
netstat -tulpn
Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
tcp6 0 0 :::80 :::* LISTEN -
Apache Traffic
Public Requests to the Apache server on the private subnet does not work.
wget http://127.0.0.0.1/index.html => success
# public IP requests
wget http://xxx.x.x.x/index.html => failure
Connecting to xxx.x.x.x:80... => hangs
From the NAT host terminal
sudo tcpdump -i any -n port 80
sudo: unable to resolve host ip-10-0-0-71
15:22:17.668089 IP 10.0.10.102.54033 > X.X.X.X.80: Flags [S], seq 848018267, win 26883, options [mss 8961,sackOK,TS val 19553465 ecr 0,nop,wscale 7], length 0
15:22:17.668111 IP 10.0.0.71.54033 > X.X.X.X.80: Flags [S], seq 848018267, win 26883, options [mss 8961,sackOK,TS val 19553465 ecr 0,nop,wscale 7], length 0
What do we need to do so Apache will work from the private subnet?
