AirRouter AirOS Router Manual PDF (Setup & Configuration Guide)

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Ubiquiti Networks, Inc.

Chapter 3: AirOS™

AirRouter User Guide

•

Private Port

The TCP/UDP port of the application

running on the host which is connected to the internal

network. The specified port will be accessible from the

external network.

•

Type

The L3 protocol (IP) type which needs to be

forwarded from the internal network.

•

Public Port

The TCP/UDP port of the AirRouter which

will accept and forward the connections from the

external network to the host connected to the internal

network.

•

Comments

Enter a brief description of the port

forwarding functionality such as FTP server, Web server,

or game server.

•

Enabled

Enables or disables the effect of the particular

port forwarding entry. All the added firewall entries are

saved in the system configuration file, however only

the enabled port forwarding entries are used on the

AirRouter.

Save your port forwarding entries by clicking

Save

discard your changes by clicking

Cancel

Auto IP Aliasing

Automatically generates an IP Address

for the corresponding WLAN/LAN interface if enabled.

The generated IP address is a unique Class B IP address

from the 169.254.X.Y range (Netmask 255.255.0.0) which is

intended for use within the same network segment only.

Auto IP always starts with 169.254.X.Y while X and Y are

last 2 digits from the MAC address of the device (i.e. if the

MAC is 00:15:6D:A3:04:FB, Generated unique Auto IP will

be 169.254.4.251).

IP Aliases

IP aliases for the internal and external network

interface can be configured. IP Aliases can be specified

using the

IP Aliases

configuration window which is opened

when you click

Configure

•

The alternative IP address for the LAN or WLAN

interface, which can be used for the routing or device

management purposes.

•

Netmask

The network address space identifier for the

particular IP Alias.

•

Comments

Field used for a brief description of the

purpose of the alias.

•

Enabled

Enables or disables the particular IP Alias. All

added IP Aliases are saved in the system configuration

file, however only the enabled IP Aliases are active on

the AirRouter.

Newly IP Aliases can be saved by click the

Save

button

or discarded by clicking the

Cancel

button in the

Aliases

configuration window.

Multicast Routing Settings

With a multicast design, applications can send one copy

of each packet and address it to a group of computers

that want to receive it. This technique addresses packets

to a group of receivers rather than to a single receiver.

It depends on the network to forward the packets to

the hosts which need to receive them. Common routers

isolate all the broadcast (thus multicast) traffic between

the internal and external networks, however the AirRouter

provides the multicast traffic pass-through functionality.

Enable Multicast Routing

Option enables multicast

packet pass-through between internal and external

networks while the AirRouter is operating in

Router

mode.

Multicast intercommunication is based on Internet Group

Management Protocol (IGMP).

Multicast Upstream

Specify the source of Multicast

traffic, i.e. defines where multicast traffic comes from.

Firewall Settings

Firewall functionality on any router interface can be

enabled using the

Enable Firewall

option. Router Firewall

rules can be configured, enabled or disabled in the

Firewall

configuration window which is opened by clicking

Configure

Firewall entries can be specified by using the following

criteria:

•

Interface

The interface (WLAN, LAN or PPP) where

filtering of the incoming/passing-through packets is

processed.

•

IP Type

Sets which particular L3 protocol type (IP, ICMP,

TCP, UDP, P2P) should be filtered.

•

Source IP/Mask

The source IP of the packet (specified

within the packet header), usually it is the IP of the host

system which sends the packets.

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Ubiquiti Networks, Inc.

Chapter 3: AirOS™

AirRouter User Guide

•

Src Port

The source port of the TCP/UDP packet

(specified within the packet header), usually it is the port

of the host system application which sends the packets.

•

Destination IP/mask

The destination IP of the packet

(specified within the packet header), usually it is the IP

of the system which the packet is addressed to.

•

Dst Port

The destination port of the TCP/UDP packet

(specified within the packet header), usually it is the

port of the host system application which the packet is

addressed to.

•

Comment

Field used to enter a brief description of the

firewall entry.

•

Enables or disables the effect of the particular

firewall entry. All the added firewall entries are saved in

the system configuration file, however only the enabled

firewall entries will be active during AirRouter operation.

•

Not

Can be used for inverting the Source IP/mask,

Source Port, Destination IP/mask and Destination Port

filtering criteria (i.e. if not is enabled for the specified

Destination Port value 443, the filtering criteria will be

applied to all the packets sent to any Destination Port

except the 443 which is commonly used by HTTPS).

Firewall entries can be saved by clicking

Save

or discarded

by clicking

Cancel

in the

Firewall

configuration window.

All active firewall entries are stored in the FIREWALL chain

of the iptables filter table, while the device is operating

Router

mode. Please refer to the iptables tutorial for

detailed description of the firewall functionality in Router

mode.

Click

Change

to save the changes made on the

Network

tab.

Static Routes

In this section you can manually add static routing rules to

the System Routing Table, this allows you to specify that a

specific target IP address (es) passes through a determined

gateway. Click

Configure

to add an entry.

For each entry you must specify a valid Target Network IP,

Netmask, Gateway IP, and optionally a comment. Select

to enable the rule. Click

Save

to save your entries or

Cancel

to discard them.

Advanced

The

Advanced

tab handles advanced routing and wireless

settings. The advanced wireless settings should be used

by technically advanced users who have a sufficient

knowledge about wireless LAN technology. These settings

should not be changed unless you know the effect the

changes will have on your AirRouter.

Advanced Wireless Settings

The 802.11n data rates include MCS0, MCS1, MCS2, MCS3,

MCS4, MCS5, MCS6, MCS7 for 1x1 chain devices and MCS8,

MCS9, MCS10, MCS11, MCS12, MCS13, MCS, MCS15 for

2x2 chains devices. The ACK timeout has a critical impact

on performance in 802.11n outdoor links.

RTS Threshold

Determines the packet size of a

transmission and, through the use of an access point,

helps control traffic flow. The range is 0-2346 bytes, or

word “off”

. The default value is 2346 which means that RTS

is disabled.

RTS/CTS (Request to Send/Clear to Send) are the

mechanisms used by the 802.11 wireless networking

protocol to reduce frame collisions introduced by the

hidden terminal problem. RTS/CTS packet size threshold is

0-2346 bytes. If the packet size the node wants to transmit

is larger than the threshold, the RTS/CTS handshake

gets triggered. If the packet size is equal to or less than

threshold the data frame gets sent immediately.

Page 28 / 38

Ubiquiti Networks, Inc.

Chapter 3: AirOS™

AirRouter User Guide

System uses Request to Send/Clear to Send frames for the

handshake which provide collision reduction for access

point with hidden stations. The stations are sending a

RTS frame first while data is send only after handshake

with an AP is completed. Stations respond with the CTS

frame to the RTS which provides clear media for the

requesting station to send the data. CTS collision control

management has a time interval defined during which

all other stations hold off transmission and wait until the

requesting station finishes transmission.

Fragmentation Threshold

Specifies the maximum size

for a packet before data is fragmented into multiple

packets. The range is 256-2346 bytes, or word “off”

. Setting

the Fragmentation Threshold too low may result in poor

network performance.

The use of fragmentation can increase the reliability

of frame transmissions. When sending smaller frames,

collisions are much less likely to occur. However lower

values of the Fragmentation Threshold will result in lower

throughput as well. It is recommended that you only make

slight modifications or none at all to the Fragmentation

Threshold value. The default setting of 2346 is optimum in

most wireless network use cases.

The AirRouter has a new auto-acknowledgement

timeout algorithm which dynamically optimizes the

frame acknowledgement timeout value without user

intervention. This is a critical feature required for

stabilizing long-distance 802.11n outdoor links. The user

also has the ability to enter the value manually, but it’s not

recommended.

Distance

Specify the distance value in miles (or

kilometers) using the slider or entering the value manually.

The signal strength and throughput falls off with range.

Changing the distance value will change the ACK Timeout

to the appropriate value of the distance.

ACK Timeout

Specify the ACK Timeout. Every time the

station receives the data frame it sends an ACK frame to

the AP (if transmission errors are absent). If the station

receives no ACK frame from the AP within set timeout it

re-sends the frame. The performance drops because if too

many data frames are re-sent, thus if the timeout is set

too short or too long, it will result poor connection and

throughput performance.

Changing the ACK Timeout value will change the Distance

to the appropriate distance value for the ACK Timeout.

Auto Adjust

Control will enable the ACK Timeout

Self-Configuration feature. If enabled, ACK Timeout value

will be derived dynamically using an algorithm similar to

the Conservative Rate Algorithm (used in AirOS v3.4). It

is very recommended to use the Auto Adjust option for

802.11n.

If two or more stations are located at a considerably

different distance from the Access Point they are

associated with, the highest ACK Timeout for the farthest

station should be set on the AP side. The AirRouter

includes an improved ACK Timeout algorithm.

Aggregation

A part of the 802.11n standard that allows

sending multiple frames per single access to the medium

by combining frames together into one larger frame. It

creates the larger frame by combining smaller frames with

the same physical source and destination end points and

traffic class (i.e. QoS) into one large frame with a common

MAC header.

•

Frames

Determines the number of frames combined

on the new larger frame.

•

Bytes

Determines the size (in Bytes) of the larger frame.

Multicast Data

This option allows all the Multicast packet

pass-through functionality. By default this option is

disabled.

Enable Extra Reporting

Feature will report additional

information (i.e. Device Name) in the 802.11 management

frames. This information is commonly used for system

identification and status reporting in discovery utilities

and Router operating systems.

Enable Client Isolation

This option allows packets only

to be sent from the external network to the CPE and vice

verse (applicable for Access Point and Access Point WDS

mode only). If Client Isolation is enabled, wireless stations

connected to the same AP will not be able to interconnect

on both the layer 2 (MAC) and layer 3 (IP) level. This is

effective for associated stations and WDS peers as well.

Advanced Ethernet Settings

Enable Autonegotiation

When enabled, the device will

automatically negotiate transmission parameters with the

counterpart, such as speed and duplex. In this process, the

connected devices first share their capabilities and then

choose the fastest transmission mode they both support.

If you want to specify the values manually, disable the

Enable Autonegotiation

option and select the values:

•

Link Speed, Mbps

Selects the maximum transmission

link speed. There are two options: 10Mbps or 100Mbps.

If running extra long Ethernet cables, a link speed of

10Mbps could help to achieve better stability.

•

Enable Full Duplex

Selects the duplex mode;

if enabled, the device operates in Full Duplex

(allowing bidirectional communication in both

directions simultaneously). While disabled, the

device operates in Half-Duplex mode (allowing

bidirectional communication in both directions, but not

simultaneously and only in one direction at a time.

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Ubiquiti Networks, Inc.

Chapter 3: AirOS™

AirRouter User Guide

Traffic Shaping

Wireless Traffic shaping is dedicated to upstream and

downstream bandwidth control while looking from the

client (connected on the Ethernet interface) perspective.

The traffic can be limited at the AirRouter in the upload

and download direction based on a user defined rate limit.

This is layer 3 QoS.

Enable Traffic Shaping

This option will enable

bandwidth control on the device.

•

Incoming Traffic Limit

Specify the maximum

bandwidth value (in kilobits per second, Kbps) for traffic

passing from the wireless interface to the Ethernet

interface.

•

Incoming Traffic Burst

Specify the data volume (in

kilobytes) to which the Incoming Traffic Limit will not be

effective afterwards data connection is initiated.

•

Outgoing Traffic Limit

Specify the maximum

bandwidth value (in kilobits per second, Kbps) for traffic

passing from the Ethernet interface to the wireless

interface.

•

Outgoing Traffic Burst

Specify the data volume (in

kilobytes) to which the Outgoing Traffic Limit will not be

effective after data connection is initiated.

Services

The

Services

tab covers the configuration of system

management services SNMP, SSH, System Log and Ping

Watchdog.

Ping Watchdog

Ping Watchdog sets the AirRouter to continuously ping

a user defined IP address (it can be the Internet gateway

for example). If it is unable to ping under the user defined

constraints, the AirRouter will automatically reboot. This

option creates a kind of “fail-proof” mechanism.

Ping Watchdog is dedicated for continuous monitoring

of the particular connection to remote host using the

Ping tool. The Ping works by sending ICMP “echo request”

packets to the target host and listening for ICMP “echo

response” replies. If the defined number of replies is not

received, the tool reboots the device.

Enable Ping Watchdog

Enables the Ping Watchdog tool.

•

IP Address To Ping

Specify the IP address of the target

host which to be monitored by the Ping Watchdog tool.

•

Ping Interval

Specify time interval (in seconds)

between the ICMP “echo requests” are sent by the Ping

Watchdog Tool. The default value is

300

seconds.

•

Startup Delay

Specify initial time delay (in seconds)

until the first ICMP echo requests are sent by the Ping

Watchdog tool. The default value is

300

seconds.

The value of Startup Delay should be at least 60 seconds

as the network interface and wireless connection

initialization takes a considerable amount of time if the

device is rebooted.

•

Failure Count to Reboot

Specify the number of ICMP

echo response replies. If the specified number of ICMP

echo response packets is not received continuously, the

Ping Watchdog tool will reboot the device. The default

value is

SNMP Agent

Simple Network Monitor Protocol (SNMP) is used

in network management systems to monitor

network-attached devices for conditions that warrant

administrative attention. The AirRouter contains an SNMP

agent which allows it to communicate to SNMP manage

applications for network provisioning.

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Ubiquiti Networks, Inc.

Chapter 3: AirOS™

AirRouter User Guide

The SNMP Agent provides an interface for device

monitoring using the Simple Network Management

Protocol (an application layer protocol that facilitates the

exchange of management information between network

devices). SNMP Agent allows network administrators to

monitor network performance, find and solve network

problems. For the purpose of equipment identification,

it is always a good idea to configure SNMP agents with

contact and location information:

Enable SNMP Agent

Enables the SNMP Agent.

•

SNMP Community

Specify the SNMP community

string. It is required to authenticate access to MIB

objects and functions as an embedded password. The

device supports a Read-only community string that

gives read access to authorized management stations to

all the objects in the MIB except the community strings,

but does not allow write access. The AirRouter supports

SNMP v1. The default SNMP Community is

public

•

Contact

Specify the contact who that should be

notified in case an emergency situation arises.

•

Location

Specify the physical location of the device.

Web Server

The following Web Server parameters can be set:

Use Secure Connection (HTTPS)

If checked Web server

will use secure HTTPS mode. HTTPS mode is unchecked by

default.

•

Secure Server Port

Defines the Web Server TCP/IP port

Use Secure Connection (HTTPS)

is enabled.

Server Port

Web Server TCP/IP port setting while using

HTTP mode.

Session timeout

Specifies the maximum timeout before

the session expires. Once a session expires, you must login

again using the username and password.

SSH Server

The following SSH Server parameters can be set:

Enable SSH Server

This option enables SSH access to the

AirRouter.

•

Server Port

SSH service TCP/IP port setting.

•

Enable Password Authentication

When enabled, you

must authenticate using Administrator credentials in

order to grant SSH access to the device, otherwise an

Authentication Key will be required.

•

Authorized Keys

Click Edit to import a public key file

working to get SSH access to the device instead of using

an admin password. Click

Browse

to locate and select

the key file, then click

Import

. Click

Save

to save your

changes or

to discard your changes.

Telnet Server

The following Telnet Server parameters can be set:

Enable Telnet Server

This option activates the Telnet

access to the AirOS Device.

Server Port

Telnet service TCP/IP port setting.

NTP Client

The Network Time Protocol (NTP) is a protocol for

synchronizing the clocks of computer systems over

packet-switched, variable-latency data networks. It can

be used to set the AirRouter system time. System Time

is reported next to the every System Log entry while

registering system events if the

Log

option is enabled.

Enable NTP Client

Enables the AirRouter to obtain the

system time from a time server on the Internet.

•

NTP Server

Specify the IP address or domain name of

the NTP Server.

System Log

Enable Log

This option enables the registration routine

of the system log messages. By default it is disabled.

•

Enable Remote Log

Enables the syslog remote sending

function while System log messages are sent to a

remote server specified in the

Remote Log IP Address

and

Remote Log Port

fields.

Remote Log IP Address

The host IP address where

syslog messages should be sent. Remote host should

be configured properly to receive syslog protocol

messages.

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