What is a Connection Table in Stateful Firewall?

What is a Connection Table in Stateful Firewall?


The Connection Table is a very important part of the Stateful Packet Inspection (SPI) process. It contains information about every connection that has been seen on the firewall. SPI maintains an in-memory table called the Connection Table, which holds all connections and their state information: what packets have been seen for this connection, how long it’s been idle if it is permitted or denied by policy rules, and so on. This table can grow to be quite large with many connections over time. If you don’t keep an eye on your Connection Table size, you may find yourself running out of memory and crashing your firewalls!

In the state-full firewall, every incoming and outgoing connection is monitored by a dynamic table that contains information about each active connection. The number of connections that your system can track is limited by the amount of memory it has. A busy site with a large number of simultaneous traffic flows may require a very large Connection Table on a mid or high-end firewall and the table may run out of memory. If this happens, traffic is dropped until the connection table stabilizes.

What is a Connection Table in Stateful Firewall?

A connection table is a place that you create with the firewall to store something. In this case, it stores data that shows how traffic is categorized. You can then retrieve the information you keep in the connection table and see what happened over time.

Connection tables are used to track sessions over time. This can be done with either information about the clients or information about the servers. Using a connection table in a stateful firewall is useful when you want to keep a record of your users’ activity for a period of time. It also gives you an easy way to do analytics, including where your users are from, what protocols they use and any errors they might have encountered.

Why is it important to have one?

It is important to have connection tables in stateful firewalls because they are able to map outgoing connections with established incoming connections. Connection tables can also be used to maintain a record of connection activities for the stateful firewalls. This data can be used to create security reports and monitor network traffic.

Connection tables are especially important for stateful firewalls because they make sure that these sets of machines can keep track of the incoming and outgoing network connections. This makes it easier to regulate what kind of data is allowed to come in and which data needs to be blocked. The connection table can also be used to monitor network activity and create security reports.

What are the benefits of having a connection table?

The primary benefit of having a connectionless firewall is that it can help handle unexpected issues. When you have a connection table, your device will need to decide what the next step for each packet is before sending it on its way. If something goes wrong with this process, then there is a chance that the connection could time out and cause an outage.

Another benefit of having a connection table is that the table allows you to identify connections between packets. This is great for inspecting and analyzing traffic behavior, as it can help identify problems such as packet flooding. Packet inspection is also much faster with a connection table because you can set specific filters to inspect certain data formats or connections that have been flagged as malicious. If you only have a standard firewall, then all of the data packets will need to be inspected in order to find the flagged connections. A connection table also allows for more efficient memory allocation on some devices that can cause problems with your device’s CPU.

How many types of Connection tables are there?

There are two Connection tables: the Interface table and the Adjunct table.

The Adjunct table is used for filtering packets that are associated with an existing connection, using the source and destination addresses of this connection. The firewall will add a chain to either forward, block or discard packets. These chains are created after any user-defined rules have been matched.

The Adjunct table is used for filtering packets that come from an outside network and enter through the interface to determine which chain to add these packets to. The Interface table is used for filtering packets that are ‘inbound’ through an interface after all of the user-defined rules have been matched.


A Connection Table is a list of connections that have been established and are currently active. It’s used to track the stateful information about each connection, such as what type of protocol was being used when it came into existence, wherein the network it originated from or will terminate at, whether there were any errors during its establishment process, etc. A Connection Table can be very small if only a few connections exist but becomes increasingly large as more and more data flows through your system and more and more connections are created. This is where the importance of connection limiting comes into play: Connection Limits ensure that your firewall only allows a certain number of connections to be established at any given time. This ensures your connection table cannot become too large, which would degrade the performance of your device as it struggles to keep track of each and every connection.

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