The "ip_conntrack: table full, dropping packet" error message indicates that the Linux kernel's connection tracking table, which is used by the iptables firewall to track the state of network connections, is full. This can happen if the firewall is processing a very large number of connections, or if there are a large number of connections in the firewall's state table that are not being closed properly.
To resolve this issue, you can try increasing the size of the connection tracking table. This can be done by modifying the nf_conntrack_max sysctl parameter. For example, to increase the table size to 65536, you can use the following command:
sudo sysctl -w net.netfilter.nf_conntrack_max=65536
You can also try reducing the number of connections that are being tracked by the firewall. This can be done by reducing the number of services that are exposed to the network, or by configuring the firewall to drop connections that are not needed.
It is also a good idea to monitor the usage of the connection tracking table over time, and to adjust the table size as needed based on the volume of traffic that the firewall is handling.
Finally, if you are experiencing this issue frequently, it could be a sign of a larger problem, such as a network attack or a misconfigured application that is generating a large number of connections. In these cases, it may be necessary to take further steps to identify and address the root cause of the issue.