Troubleshooting
Problem
This document discusses the TCP/IP ports needed to access the IBM i NetServer.
Resolving The Problem
Prior to Windows 2000, Windows OS versions all used NetBT (NetBIOS over TCPIP) for network drive connections. NetBT uses UDP ports 137 and 138 and TCP port 139. After the introduction of Windows 2000, Windows versions used CIFS (Common Internet File System). CIFS can use UDP ports 137 and 138, and TCP ports 139 and 445. Windows can send and receive data on these ports while providing CIFS service. CIFS does not typically use ports 137, 138, 139, but can still use them.
For users to access IBM i NetServer, the following must be considered, in addition to basic configuration and management:
For users to access IBM i NetServer, the following must be considered, in addition to basic configuration and management:
| o | Some networks, particularly internet service providers, block NetBIOS traffic. If this is the case, the user may still be able to locate the IBM i NetServer by TCP/IP address (rather than name). |
| o |
If there is a firewall in place, at a minimum, port 445 must be unrestricted for TCP.
137 - NetBIOS Name Service (name lookup requests) 138 NetBIOS browsing (datagram services) 139 - NetBIOS Session Service (file and print sessions) 445 - Native TCP Session Service for Microsoft Windows 2000/XP An easy way to check if the ports are unrestricted is to Telnet to each of the ports using the syntax: TELNET nnn.nnn.nnn.nnn ppp (substituting the TCP/IP address and the port number). If Telnet gets to the port successfully, a blank DOS window with a blinking cursor appears. If Telnet fails to get to the port, the following message is issued: Could not open a connection to host on port. Alternatively, if IBM i Access Client Solutions - Windows Application Package is installed on the PC, the cwbping utility can be used to ping the ports. To do so, run the following commands at a PC DOS command prompt:
...where <IBMiHostName> can be the IBM i host name or IP address.
A successful connection will return the following information: I - Verifying connection to system IBMiHostName... I - Successfully connected to server application: #137 I - Connection verified to system IBMiHostName If the port is blocked, the following information will be returned: I - Verifying connection to system IBMiHostName... E - CWBCO1003 - Sockets error, function connect() returned 10061 E - CWBCO1049 - The iSeries server application is not started E - CWBCO1008 - Unable to connect to server application #137, returned 10061 E - CWBCO1016 - Connection verify to system IBMiHostName failed Repeat cwbping for ports 139 and 445 |
Related Information
[{"Type":"MASTER","Line of Business":{"code":"LOB57","label":"Power"},"Business Unit":{"code":"BU058","label":"IBM Infrastructure w\/TPS"},"Product":{"code":"SWG60","label":"IBM i"},"ARM Category":[{"code":"a8m0z0000000CLSAA2","label":"Integrated File System->NetServer"}],"ARM Case Number":"","Platform":[{"code":"PF012","label":"IBM i"}],"Version":"All Versions"}]
Historical Number
22204642
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Document Information
Modified date:
20 December 2021
UID
nas8N1017522