Communication between VPC subnet instances

andreaxi picture andreaxi · Sep 4, 2012 · Viewed 13.7k times · Source

I'm trying to set up a very simple VPC environment, but I'm having troubles making the instances in the subnet see each others: ie, when I ping 10.0.0.10 from 10.0.0.93 it doesn't succeed.

I thought it was a problem belonging to some misconfiguration but, review everything I can't find the problem.

Here are my routes table (as default):

rtb-14f2127c, 1 Subnet, No, vpc-1ef21276 (10.0.0.0/16)
rtb-10f21278, 0 Subnets, Yes, vpc-1ef21276 (10.0.0.0/16)

Just one DHCP Option:

dopt-12f2127a    domain-name-servers = AmazonProvidedDNS;

My network ACL (inbound):

100 ALL ALL 0.0.0.0/0   ALLOW
*   ALL ALL 0.0.0.0/0   DENY

(outbound):

100 ALL ALL 0.0.0.0/0   ALLOW
*   ALL ALL 0.0.0.0/0   DENY

My security group has (inbound):

ALL sg-b3637adf 
22 (SSH)    0.0.0.0/0   
80 (HTTP)   0.0.0.0/0   
443 (HTTPS) 0.0.0.0/0   
4848    0.0.0.0/0   
8080 (HTTP*)    0.0.0.0/0   
8258    0.0.0.0/0   
24848   0.0.0.0/0   
28009   0.0.0.0/0   
28080   0.0.0.0/0   
28181   0.0.0.0/0

(outbound):

ALL 0.0.0.0/0
22 (SSH)    0.0.0.0/0   
80 (HTTP)   0.0.0.0/0   
443 (HTTPS) 0.0.0.0/0   
8080 (HTTP*)    0.0.0.0/0   
8258    0.0.0.0/0   
28009   0.0.0.0/0   
28080   0.0.0.0/0   
28181   0.0.0.0/0   

Thanks, Andrea

Answer

andreaxi picture andreaxi · Sep 5, 2012

I solved the problem: I added at the security group (both in inbound and in outbound)

ALL sg-b3637adf 

And I fixed a problem with the security group id (sg-b3637adf).

Doing these two steps made instances able to ping themselves.

For future readers, if you have a security group with ICMP ports blocked, you will not be able to ping. Make sure you have a rule in your security group to allow all ICMP access.