[RHOSP13] Recommendation to disable Path MTU in overcloud nodes

Solution In Progress - Updated -

Environment

  • Red Hat OpenStack Platform 13

Issue

  • "path MTU discovery" could be used by a malicious attacker to receive a reply from the server despite the firewall configuration by forcefully sending a large packet.

Resolution

  • Since Neutron is calculating MTU for the whole path on nodes according to data configured in its database and config files, it's acceptable to disable path MTU in host kernel.

    sysctl -w net.ipv4.ip_no_pmtu_disc=0
    

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