IPTABLES - Unexpected traffic - EC2 - Should I configure IPTABLES on instance command line?


Hi there. I'm migrating on-premise server running MySQL to a new EC2 instance (Amazon Linux 2). I'm trying to move IPTABLES configuration to EC2 as well, but I see unexpected traffic being blocked by IPTABLES. I'm starting to suspect that AWS ping the EC2 instance on time basis for monitoring and thus has being causing these unexpected traffic. Is that right ?

I know firewall rules can be configure when lunching EC2 instance, but I'd like to know whether is a good practice to define IPTABLES on instance command lines. Does IPTABLES configuration compromises AWS to monitor instances?

Should I configure IPTABLES on EC2 instances?

Thanks, Marcelo Maciel

  • Shibata/Didier. Thanks for you replies

    It's clear for me now. Thanks!

    All thouse unexpected traffic I questioned earlier were generated by "EC2 Instance Connect" and instance metadata endpoint.

    Another question: does Security Groups process its filtering at instance level? Does Security consume ane instance resource ?

posta 4 mesi fa339 visualizzazioni
3 Risposte

I prefer to use Security Groups to protect EC2 from external communication.


I can't find the documentation, but EC2 stats checks should work fine even if all packets are droped using iptables. However, I don't know about other services.

profile picture
con risposta 4 mesi fa
profile pictureAWS
verificato 4 mesi fa
  • Hi, I agree with Shibata that sec groups should be used as much as possible because it brings many advantages. But, I also agree on the fact that iptables cannot be fully fully replicated with sec group for sophisticated rules. So, I'd suggest to do as much as possible with sec group and complements with iptables


Hi Shibata. Thanks for your reply!

Security Groups is not a bad option, but it can't replace IPTABLES in full. It's only possible to create complex rules (using states and expressions) with IPTABLES.

It's not clear to me whether IPTABLES rules prevent any AWS functionaly to work

con risposta 4 mesi fa

So far, I think I should combine both IPTABLES and Security Groups.

For example, on Security Groups I would allow traffic on 22 and 3306 ports. On IPTABLES I would allow all traffic, but drop those with bad flags.

In other words, on Security Groups I could configure what is allowed and on IPTABLES I could configure how its allowed

con risposta 4 mesi fa

Accesso non effettuato. Accedi per postare una risposta.

Una buona risposta soddisfa chiaramente la domanda, fornisce un feedback costruttivo e incoraggia la crescita professionale del richiedente.

Linee guida per rispondere alle domande