# internal() source options

The `internal()` driver has the following options:

## host-override()

|   
---|---  
Type: | string  
Default: |   
  
_Description:_ Replaces the ${HOST} part of the message with the parameter string.

## log-iw-size()

|   
---|---  
Type: | number  
Default: | 100  
  
_Description:_ Specifies the source window size - the maximum number of in-flight messages permitted by the source before flow control is enforced. This only applies when `flow-control` is enabled.

Warning
```
 
    <p>If you change the value of <code>log-iw-size()</code> and <code>keep-alive()</code> is enabled, the change will affect only new connections, the <code>log-iw-size()</code> of kept-alive connections will not change. To apply the new <code>log-iw-size()</code> value to every connection, <a href="/docs/axosyslog-core/quickstart/managing-and-checking-linux/#restart-axosyslog">restart the <code>syslog-ng</code> service</a>. A simple configuration reload is <em>NOT</em> sufficient.</p>
    
```

If the source is receiving data using the UDP protocol, always [restart the `syslog-ng` service](../../../docs/axosyslog-core/quickstart/managing-and-checking-linux/index.md#restart-axosyslog) after changing the value of `log-iw-size()` for the changes to take effect.

Note that when using `disk-buffer()`, the messages stored on disk are not included in the window size calculation. For details about the effects of this parameter, see [Managing incoming and outgoing messages with flow-control](../../../docs/axosyslog-core/chapter-routing-filters/concepts-flow-control/index.md).

## normalize-hostnames()

|   
---|---  
Accepted values: | `yes`, `no`  
Default: | `no`  
  
_Description:_ If enabled (`normalize-hostnames(yes)`), AxoSyslog converts the hostnames to lowercase.

## program-override()

|   
---|---  
Type: | string  
Default: |   
  
_Description:_ Replaces the ${PROGRAM} part of the message with the parameter string. For example, to mark every message coming from the kernel, include the `program-override("kernel")` option in the source containing `/proc/kmsg`.

## tags()

|   
---|---  
Type: | string  
Default: |   
  
_Description:_ Label the messages received from the source with custom tags. Tags must be unique, and enclosed between double quotes. When adding multiple tags, separate them with comma, for example, `tags("dmz", "router")`. This option is available only in version 3.1 and later.

## use-fqdn()

|   
---|---  
Type: | yes or no  
Default: | no  
  
_Description:_ Add Fully Qualified Domain Name instead of short hostname. This option can be specified globally, and per-source as well. The local setting of the source overrides the global option if available.

Last modified July 16, 2023: [Unrelated formatting fixes (56c0224)](<https://github.com/axoflow/axosyslog-core-docs/commit/56c022402725d65b86170fb3530ae5d7af3198f6>)