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December 24 - AppLogic 2.4.7 is now available and is the latest production release!

OUT: Single Host Output Gateway Appliance

Latest version: 2.2.1

	At a Glance
	Catalog	System
	Category	Gateways
	User volumes	no
	Min. memory	40 MB
	OS	Linux
	Constraints	no
	Questions/Comments	Ask Forum

Functional overview

OUT is an output gateway that provides access to a network host located outside of an application. OUT accepts traffic from the application on its in terminal and forwards it through its external interface to the remote host.

OUT has a firewall that allows only outgoing traffic (connections and datagrams); it drops incoming traffic that is not for an already established connection or related to a datagram request.

OUT passes all traffic to the remote host specified by the remote_host property. The remote host can be specified either as a DNS host name (e.g., www.3tera.com) or as an IP address in "dots" notation (e.g., 192.168.1.1). If the remote host is configured using a DNS name, the OUT gateway will ensure that if the name-to-IP mapping changes, the gateway will redirect its traffic to the new IP address.

OUT is used to access services outside of the application, such as an external database, web service or document repository. OUT is the only appliance in an application that needs to be configured with the name or IP address of the remote host; the remaining application components can access that host simply by being connected to the OUT appliance input.

Boundary

Resources

Resource	Minimum	Maximum	Default
CPU	0.05	4	0.05
Memory	40 MB	2 GB	40 MB
Bandwidth	1 Mbps	100 Mbps	1 Mbps

Terminals

Name	Dir	Protocol	Description
`in`	in	any	Accepts traffic to be sent out the remote host
`mon`	out	cce	Sends performance and resource usage statistics

The external interface is enabled. It is used for outgoing traffic. It is configured to send all traffic to the remote host.

The default interface is enabled. It is used for maintenance (incoming ssh connections).

User Volumes

None

Properties

Property name	Type	Description
`remote_host`	String	Defines the remote host to forward all traffic to. This can be the DNS name of the host or its IP address in "dots" notation. This property is mandatory.
`dns_poll`	Integer	The poll interval, in seconds, that OUT will use when checking the mapping of the DNS name of `remote_host` to IP address (used only if `remote_host` is specified as a DNS name). Set to 0 to disable polling and not try to detect changes. Default is 3600 seconds (1 hour).
`ip_addr`	IP Address	Defines the IP address of the `external` interface of the gateway. This property is mandatory.
`netmask`	IP address	Defines the network mask of the `external` interface. This property is mandatory.
`gateway`	IP address	Defines the default network gateway for the external interface. It can be left blank only if the remote host is on the same subnet; must be specified otherwise. Default is blank.
`dns1`	IP address	Defines the primary DNS server. It can be left blank if the remote host is specified by its IP address; must be specified otherwise. Default is blank.
`dns2`	IP address	Defines the secondary DNS server, which will be used if the primary DNS server does not respond. Default is blank (not used).

Typical Usage

The following diagram shows a typical usage of OUT for a simple web server application that accesses external database while serving user requests:

Summary of Parts

in1 � input gateway appliance, class in
web1 - web server appliance, class apache
out1 - output gateway appliance, class out

in1 passes client web requests arriving from outside the application to the web1 server. web1 serves static content by itself; for dynamic content, scripts that run in web1 access an external database through the out1 gateway. The out1 gateway is configured with the host name of the server that provides the external database.

The following sections describe the configuration of OUT in several typical use cases:

OUT with a remote host by DNS name

This mode is used when the remote host has a valid entry in the DNS server. In this mode, OUT can resolve the DNS name and mointors for changes to the DNS entry for the remote host.

OUT will resolve remote_host using the DNS servers configured as properties. In this mode, at least dns1 must be set.

Example:

Property name	Value	Description
`remote_host`	`www.google.com`	DNS name or the IP address of the remote host to forward all traffic to.
`dns_poll`	`3600`	The poll interval for the DNS name, in seconds.
`ip_addr`	`192.168.1.12`	IP address for the gateway itself.
`netmask`	`255.255.255.0`	Netmask for the gateway.
`gateway`	`192.168.1.1`	IP address of a router used to reach remote networks.
`dns1`	`192.168.1.1`	Address of a DNS server to use to resolve `remote_host`.
`dns2`	`192.168.1.2`	Address of a backup DNS server (used if the first one is not available).

OUT with a remote host by IP address

This mode is used when the IP address of remote_host is fixed or has no DNS records. In this mode the dns_poll proprty is ignored.

Example:

Property name	Value	Description
`remote_host`	`66.102.7.104`	DNS name or the IP address of the remote host to forward all traffic to.
`ip_addr`	`192.168.1.12`	IP address for the gateway itself.
`netmask`	`255.255.255.0`	Netmask for the gateway.
`gateway`	`192.168.1.1`	IP address of a router used to reach remote networks.

Notes

OUT is not used for accessing multiple hosts with different addresses. Applications that need to access multiple hosts through the same output, such as STMP servers, can use the NET gateway appliance.