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# B
Client Server Communications

## Client-Server Communications on UNIX

Many of the problems that LSM users report when they set up and configure LSM are actually problems with the communications in their networks. This section contains a procedure for testing the communications in a network.

### How to Troubleshoot IP Errors

1. Read this section. Document the steps you take and the results, especially error messages, in case you need to contact Oracle Worldwide Customer Support.
2. Set up host tables for LSM clients and LSM servers. See "How to Set Up Host Tables".
3. Disable other name servers to simplify testing. See "How to Disable Name Servers for Troubleshooting".
4. Use `ping` to establish basic connectivity. See "How to Use ping to Verify Network Connections".
5. Use `rpcinfo` to verify that sessions can be established and that portmapping is correct. See "How to Use rpcinfo to Verify that Sessions Can Be Established".

### How to Set Up Host Tables

Legato recommends that you troubleshoot IP problems using only host tables. Troubleshooting using only host tables does not mean you cannot use your name service, for example, DNS, with LSM. Test using only host tables to determine whether you have LSM installed correctly. After you know LSM works with host tables, you can enable whatever name server you are using.

To configure host tables on a server or client:

1. On the LSM client, list the client and the LSM servers to which it connects, for example:

       127.0.0.1 localhost loopback
       123.456.789.111 client client.domain.com
       123.456.789.222 server server.domain.com

2. On the LSM server, list the LSM server itself and all of its clients, for example:

       127.0.0.1 localhost loopback
       123.456.789.111 server server.domain.com
       123.456.789.222 client client.domain.com

3. Use the guidelines in "How to Use ping to Verify Network Connections" to ensure the highest success rate for host table parsing within any operating system.

Notes for host table configuration:

- Do not use blank lines in the body of your host tables.
- The end of the host table should always contain a blank line.
- The first unremarked entry should always be the loopback line in the exact order and format shown above.
- The last character of each unremarked line should be a space, not a carriage return.

On UNIX platforms, the host tables reside in /etc/hosts.

Host tables can be used in addition to DNS where necessary, but it is simplest to temporarily disable DNS for troubleshooting purposes.

### How to Disable Name Servers for Troubleshooting

To simplify the troubleshooting of name resolution problems, Legato recommends disabling services like DNS, WINS, and DHCP. If you have name resolution problems, first configure only the host tables for your machines, then test your backups.

Some common problems you may encounter with DNS, WINS, and DHCP services:

- The DNS is not configured with a reverse lookup table.
- The clients are configured with the wrong IP addresses for DNS or WINS servers.
- The DHCP services do not properly update the WINS server with new addresses.

DNS does not need to be disabled for your entire network, only for the initial setup of the LSM clients and the LSM server you want to test. Only disable the ability of a client to obtain IP naming information from a DNS server. Typically, you do not need to disable the DNS server itself.

To disable the DNS server on most UNIX platforms, rename the file /etc/resolv.conf and reboot.

For a Solaris you can, instead of renaming resolv.conf, set up the IP name search order so that the host table is searched before DNS.

To set up the IP name search order:

1. Edit the /etc/nsswitch.conf file and verify that the /etc/resolv.conf file exists.
2. Set the host file to be first in search order, with DNS second and NIS last, for example:

       hosts: files [NOTFOUND=continue] DNS [NOTFOUND=continue] nis

### How to Use ping to Verify Network Connections

After you have created the host tables, test with `ping`. Use just the steps marked with an asterisk (*) if the server is the only client.

On the LSM client:

- `ping` the client short name (host name) from the client
- `ping` the client long name (host name plus domain information) from the client
- `ping` the client IP address from the client
- `ping` the server short name from the client
- `ping` the server long name from the client
- `ping` the server IP address from the client

  The following example shows pinging the client short name and client long name from a LSM client called mars in the oak domain:

      ping mars
      ping mars.oak.com

On the LSM server:

- `ping` the server short name from the server *
- `ping` the server long name from the server *
- `ping` the server IP address from the server *
- `ping` the client short name from the server
- `ping` the client long name from the server
- `ping` the client IP address from the server

### How to Use rpcinfo to Verify that Sessions Can Be Established

If `ping` is successful and backup problems still exist, you can also test with `rpcinfo`. Because LSM relies heavily on mapping of ports, use `rpcinfo` to test the operation of the portmapper. Using `ping` tests the connection up to the network layer in the OSI model, `rpcinfo` checks for communication up to the session layer.

Use the same tests with `rpcinfo` as with `ping`. Run just the steps marked with an asterisk (*) if the server is the only client.

For `rpcinfo` to be used successfully, the machine whose hostname is entered on the command line must have a portmapper running. Legato portmappers are compatible with fully functional portmappers from other vendors (this is called a third-party portmapper) in most cases. If you are using a product that provides its own portmapper, Legato recommends not loading the third-party portmapper until you have verified that LSM works with the rest of your environment. This process lets you test portmapper compatibility without adding other unknowns.

On Solaris, the `rpcbind` daemon must be running. The `rpcinfo` utility is part of the operating system.

The syntax for using `rpcinfo` to display ports using TCP is:

    rpcinfo -p hostname

Substitute the long name and short name for the variable hostname, just like for `ping`.

You can view other `rpcinfo` command line options by typing `rpcinfo` at the command line. Notes on the `rpcinfo` command and its error messages are available in the UNIX man page for `rpcinfo`. Repeat `rpcinfo` using all of the locations and all of the iterations listed in this document for `ping`.

When `rpcinfo` runs successfully, the output is a list of port numbers and names. For troubleshooting, we are only interested in the exact text of any error messages. Typical successful responses have the following format:

    rpcinfo for mars
    program vers proto   port
    100000    2   tcp    111  portmapper
    100000    2   udp    111  portmapper
    390103    2   tcp    760
    390109    2   tcp    760
    390110    1   tcp    760
    390103    2   udp    764
    390109    2   udp    764
    390110    1   udp    764
    390113    1   tcp   7937
    390105    5   tcp    821
    390107    4   tcp    819
    390107    5   tcp    819
    390104  105   tcp    822

### How to Verify Firmware for Switches and Routers

If you are using switches or routers from any vendor, make sure that the switch or router firmware is dated after August 1995 (wherever they exist on your network) to ensure that RPC traffic is handled properly. Most of the switch and router vendors with whom we have worked have significantly improved their handling of RPC traffic since August 1995.

### Naming Requirements

LSM UNIX clients release 4.2 and later use the servers file located in the /nsr/res subdirectory to determine if a LSM server is authorized to back up the client's data.

Make sure the servers file on a client contains both the short name and long name of the server you want to back up that client's data. For example, the servers file on a LSM client would contain the following names for a LSM server named mars located in the oak.com domain:

    mars
    mars.oak.com

In the Clients resource, list both the short name and the long name, plus any other applicable aliases for each client, in the Alias attribute.

### Binding to Server Errors

LSM is designed to follow the client/server model, where servers provide services to the client through the Remote Procedure Call (RPC). These services live inside of long-lived processes, known as daemons.

For clients to find these daemons, the daemons must be registered with a registration service. When the daemons start up, they register themselves with the registration service provided by the portmapper.

LSM servers provide a backup and recover service. They receive data from clients, store the data on backup media, and retrieve it on demand. If the LSM daemons are not running and a LSM service is requested, you receive the following messages in your savegroup completion mail:

    "Server not available"
    "RPC error, remote program is not registered"

These messages indicate that the LSM daemons `nsrd`, `nsrexecd`, `nsrindexd`, `nsrmmd`, and `nsrmmdbd` may not be running. To restart the daemons, become root and enter the following command at the shell prompt:

    /etc/init.d/networker start

## Client/Server Communications on Windows NT

You establish communication between the LSM server and its clients by assigning values in both the Set Up Server dialog box and the Client dialog box of each client. To help you understand how these values work together, this section discusses communication issues internal to LSM. LSM relies on full and accurate configuration of the network to implement features that protect data and ensure security.

Configure your server by using the Set Up Server dialog box (Figure B-1). Here you make choices that affect the performance and security of your backups, such as setting the server parallelism, enabling concurrent devices, and adding or changing LSM administrators. You also use the Set Up Server dialog box to provide important company and product information that is required for registering your LSM products.

#### Figure B-1 Set Up Server Dialog Box

Click Set Up Server in the Server window to open the Set Up Server dialog box. The Set Up Server dialog box contains overlapping tabs containing resource attributes to configure your LSM server. Many of these attributes are determined when you initially install and register your LSM server software. Some attributes are read-only, or contain information more advanced and detailed than most LSM users need, particularly if Hidden Attributes is enabled. Legato technical support engineers may request that you provide information displayed in these attributes to understand your system configuration. Click Field Help to learn more about each attribute.

### Configuring Server Communications

The following sections address various client-server communication issues using LSM.

#### Name Resolution

In a pure Windows NT environment, you may find using WINS or LMHOSTS is adequate for using LSM. However, using LSM with other types of clients requires using a local host file or DNS name resolution.

You must add the LSM server name to either the local HOSTS file located in %SystemDrive%\system32\drivers\etc or the Domain Name Server (DNS) which contains the names of all the servers on your network.

#### Backup Operators Group

The Backup Operators local group provides its members the rights necessary to backup and recover data from a Windows NT system. A user requesting a backup must be in the Backup Operators or Administrators group of the domain into which they are logged. The Backup Operators group is assigned on a machine-by-machine basis. It is not assigned globally by the domain. If you are having trouble performing tasks on one LSM server but not another, check the problematic machine's Backup Operators group to ensure you are properly assigned.

#### DHCP Clients

Typically, addresses for Dynamic Host Configuration Protocol (DHCP) clients change because they use dynamic addressing. If your LSM server is a DHCP client, you must reserve a static TCP/IP address on your DHCP server. If the address changes, the authorization code for that LSM server becomes invalid.

#### SAP

LSM uses Service Advertising Protocol (SAP) to resolve IPX/SPX names into network addresses. Because of the nature of SAP, LSM can resolve IPX/SPX hostnames only if the named machine is up and running. When using IPX/SPX, make sure the SAP Agent is installed, and that SPX has been started.

#### Backup and Recover Service

In the Windows NT operating system, the LSM Backup and Recover Server service is normally started by the Windows NT System account. This allows the services to be running even if no one is logged onto that system.

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