Oracle 26ai TCP Settings and Access Control in sqlnet.ora<

**Oracle AI Database 26ai** uses `sqlnet.ora` (typically in `$ORACLE_HOME/network/admin` or the Grid Infrastructure home for listeners) for TCP protocol settings and network access control.[]() ### TCP Access Control (Valid Node Checking) This restricts which clients can connect via the listener based on hostname or IP: - **TCP.VALIDNODE_CHECKING** = `yes` | `no` (default: `no`) Enables the feature. Incoming connections are allowed only if they match the invited/excluded lists.[]() - **TCP.INVITED_NODES** = `(hostname|ip, ...)` Clients allowed to connect. Takes precedence over excluded nodes. Supports IPv4 wildcards (e.g., `192.0.*`) and CIDR for IPv4/IPv6.[]() - **TCP.EXCLUDED_NODES** = `(hostname|ip, ...)` Clients denied access. Supports the same wildcard/CIDR syntax.[]() Example**:

TCP.VALIDNODE_CHECKING=yes
TCP.INVITED_NODES=(sales.example.com, 192.168.*, 2001:DB8:200C:433B/32)
TCP.EXCLUDED_NODES=(finance.example.com, 10.0.0.5)

Notes**:

• Set these in the listener’s sqlnet.ora (critical in RAC: use the Grid home, and include SCAN/VIP/local IPs).
• Reload with lsnrctl reload (or stop/start the listener).
• Denied connections typically fail with ORA-12537.
• Settings apply to all PDBs in a multitenant database.

[]() Other Relevant TCP Parameters

• TCP.CONNECT_TIMEOUT — Time (ms/sec/min) for a client to establish a TCP connection (default: 60 sec).
• TCP.QUEUESIZE — Max pending connection queue length on the TCP listening socket.
• TCP.ALLOWED_PROXIES — List of Oracle Connection Manager addresses allowed to forward client IPs.
• TCP.NODELAY — Enables/disables Nagle’s algorithm (yes|no).

These are standard Oracle Net parameters and remain applicable in 26ai (with some unrelated changes to wallet/cert handling).[]()

Protocol addresses using the SPX or LU6.2 protocol must be replaced. Oracle Net provides support for the following network protocols:
1) TCP/IP, 2) TCP/IP with SSL, 3) Named Pipes, 4) SDP
Protocol.ora File Operations and Functionality (Legacy)
The protocol.ora file is required when "unusual" protocols are introduced into the Oracle environment, rendering the default protocol settings inappropriate. The protocol.ora file also defines node-specific and protocol-specific addressing information for certain non-standard protocols.
The following protocols require parameters to be listed in protocol.ora:

1. APPC/TCPIP
   
   APPC/TCPIP is a protocol used in Oracle Network Services to allow communication between Oracle databases and IBM mainframe systems. It stands for "Advanced Program-to-Program Communication over Transmission Control Protocol/Internet Protocol".
   

   • APPC (Advanced Program-to-Program Communication):
     • This is a protocol developed by IBM for communication between programs on different systems. It enables distributed applications to communicate with each other in a standardized way, regardless of the underlying network architecture.
   • TCP/IP (Transmission Control Protocol/Internet Protocol):
     • This is the foundational protocol suite of the internet. It defines the rules for how data is packetized, addressed, transmitted between various machines, and reassembled at the destination.

   
   How APPC/TCPIP Works in Oracle:

   • Oracle Database Gateway for APPC:
     • Oracle provides a gateway that allows Oracle databases to communicate with IBM mainframe systems using the APPC protocol over TCP/IP networks.
   • Functionality:
     • The gateway acts as a bridge, translating between the Oracle Net protocol used by Oracle databases and the APPC protocol used by mainframe applications.
   • Benefits:
     • Enables seamless integration between Oracle databases and mainframe applications.
     • Allows distributed transactions and data access across heterogeneous environments.
     • Provides location transparency, meaning that applications can access mainframe resources without needing to know their physical location.

   
   In essence: APPC/TCPIP is a crucial protocol for organizations that need to integrate their Oracle databases with applications running on IBM mainframe systems. It allows for efficient and reliable communication between these disparate systems, enabling businesses to leverage their existing IT investments and build distributed applications.
2. ASYNC
3. X.25
4. OSI4

Following is a sample protocol.ora file for cross-protocol communications between LU6.2 and TCP/IP:

PROTOCOL.ORA
LOCAL_LOOKUP.dilbert=
(ADDRESS_LIST=
(ADDRESS=
(PROTOCOL=tcpip)
(CONNECT_PROFILE=hnl1)
(MODE=ORALU62)
(TPN_PROFILE=HSW)
))

For a unified protocol environment such as TCP/IP, the protocol.ora file is not used.
But there is one significant exception to this rule, which we will look at in the next lesson.

[1] directory naming: Directory Naming enables clients to connect to the database making use of information stored centrally in an LDAP-compliant directory server such as Active Directory.