Understanding "XLATE" (translation) table in Cisco ASA Firewall
Understanding "XLATE" (translation) table in Cisco ASA Firewall
Many of you already heard about the "XLATE" table in Cisco ASA Firewall but some of you want to understand what exactly it is and what is the purpose of this table.
The "XLATE" table in an ASA firewall represents the translation table used for Network Address Translation (NAT). It's an essential component that keeps track of the mapping between real IP addresses and their translated (mapped) counterparts. This table is required for the firewall to maintain and translate private IP addresses to public ones, allowing communication over the internet.
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| Fig 1.1- Cisco ASA XLATE Table |
- Real IP Address: The actual IP address assigned to a device within a private network.
- Mapped (Translated) IP Address: The IP address that the real IP is translated to, which is used for communication outside the private network.
Here's what the xlate table stores:
1. Original Source and Destination Addresses: These are the original IP addresses and port numbers of packets when they enter the firewall.
2. Translated Source and Destination Addresses: After performing any NAT or PAT operations, the xlate table stores the translated IP addresses and port numbers.
3. Protocol Information: It comprises information about the protocol being used (e.g., TCP, UDP, ICMP).
4. Session Information: The xlate table stores TCP and UDP session state information, such as established connections and timeouts.
5. Interface Information: It records the ingress and egress interfaces for packets.
6. Security Context: In multi-context mode, when the ASA acts as numerous virtual firewalls, the xlate table additionally contains information about the security context for each translation.
