CODEWITHSUNDEEP
amazon-web-servicesaws-security-group
Caterina
Caterina

Reputation: 987

Which ports are opened by default in the same security group to communicate with instances within it?

Are all ports within the same security group opened by default or should we specify them? Like for example TCP on ports 0-65535 and ICMP IPv4 on all ports?

I ask because I noticed I don't need to specify SSH port 22 within the same security group to be able to access other instances in the same security group, so I wonder if this applied to all protocols and all ports.

This is how it currently looks like. The instances within the SG have an IP in the range 172.31.80.0/20. I only allowed SSH from other security groups, not within it.

enter image description here

Upvotes: 0

Views: 752

Answers (1)

Paolo
Paolo

Reputation: 26084

By default, instances within the same security group can't talk to each other (over any port); there is an exception however for the default security group.

From the documentation:

Instances associated with a security group can't talk to each other unless you add rules allowing the traffic (exception: the default security group has these rules by default).

Upvotes: 1

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