Showing posts with label Network. Show all posts
Showing posts with label Network. Show all posts

Monday, October 21, 2019

Quickly Deploy Zabbix in CentOS7

Zabbix is a mature and effortless enterprise-class open source monitoring solution for network monitoring and application monitoring of millions of metrics. This post is going to install zabbix4.0 into a brand new Centos7.x system environment, including default installation of mariab5.5, php5.4, apache2.4 as well. 

All configurations are almost default, the ultimate goal is to  install the zabbix system in a fastest way.

Friday, April 26, 2019

Understanding Ping Command

The ping command operates by sending Internet Control Message Protocol (ICMP) Echo Request
messages to the destination computer and waiting for a response. How many of those responses are returned, and how long it takes for them to return, are the two major pieces of information that the ping command provides.

ping /?

Thursday, June 28, 2018

Gartner Magic Quadrant for Cloud Infrastructure as a Service (Worldwide) (2018,2017,2016,2015,2014,2013,2012...)

In the context of this Magic Quadrant, cloud compute IaaS (hereafter referred to simply as "cloud IaaS" or "IaaS") is defined as a standardized, highly automated offering, where compute resources, complemented by storage and networking capabilities, are owned by a service provider and offered to the customer on demand. The resources are scalable and elastic in near real time, and metered by use. Self-service interfaces are exposed directly to the customer, including a web-based UI and an API. The resources may be single-tenant or multitenant, and hosted by the service provider or on-premises in the customer's data center. Thus, this Magic Quadrant covers both public and private cloud IaaS offerings.
Gartner's two top leaders, AWS and Microsoft, didn't change for all the time from 2010 to 2018. But Google Cloud Platform has made to leader quadrant this year.

Tuesday, April 3, 2018

Free DNS Server and (from CloudFlare) - Fastest and Easiest to Remember

Google free DNS server and has been used by me for many years, since it is decent fast and also easy to remember. But now Cloudflare just announced their DNS server and on April 1st 2018.

Here is their comparison diagram with other free public DNS server providers.

Not only fastest, Cloudflare pledged that it will not write your ip to the disk and not keep your tracking data long, it will purge all logs within 24 hours. How cool is this privacy focus feature? Definitely, I will give it more try later if there is any need to use a public DNS server.

Saturday, December 9, 2017

Check Point 1100 SIP Configuration and Troubleshooting Dropped the packets due to "Violated Unidirectional Connection"

One request came up for a simple internet SIP connection to SIP provide Goldline. There are VoIP devices involved in this task, such as Cisco Router AS5350 and IP PBX, also Check Point 1100 firewall used to protect this connection.


Wednesday, September 20, 2017

My Top Internet / Network Tools

There are lots of useful sites which helps the troubleshooting procedures. I listed some common tools or websites used by myself. Please let me know what you are using and I would like to try them and add them into this list.
  1. Internet/Network Tools Portal
  2. Internet/Network Speed Test
  3. IP Subnet Calculator
  4. Network Monitoring Related
  5. DNS and Domain Name Related
  6. BGP Toolkit
  7. Your Public IP Address
  8. Online Diagram Drawing Sites
  9. Snmp tools
  10. HTTP and HTTPS Check Tools
  11. Email Diagnostic Tools
  12. Proxy Sites
  13. Remote Support / Online Meeting
  14. Remote (SSH / Telnet) Access Tools
  15. NTP Server
  16. Portable Software
  17. Online PDF Tools
  18. Network Management
    • 18.1 Log Management
    • 18.2 Configuration Management
    • 18.3 System Image Management
    • 18.4 Network Documentation
    • 18.5 Network Access Control
  19. Network Performance Monitoring
  20. Lab Environment
  21. WIFI
  22. Compliance ,Documents Mgmt, Project Mgmt

Thursday, July 27, 2017

Gartner Magic Quadrant for Network Performance Monitoring and Diagnostics (2017, 2016, 2015, 2014 )

According to Gartner, Network performance monitoring and diagnostics (NPMD) enable network professionals to understand the impact of network behavior on application and infrastructure performance, and conversely, via network instrumentation. Other users and use cases exist, especially because these tools provide insight into the quality of the end-user experience.

The fast-growing network performance monitoring and diagnostics market is helping businesses support more complex environments and services through network visibility, performance issue detection and root cause analysis.

Leaders in this industry are innovating around cloud-based monitoring, better support for software-defined environments and more flexible deployment models, according to research firm Gartner. The research firm estimates that the network performance monitoring and diagnostics tool market, which is a segment of the lager network management space, sits at $1.6 billion and is growing at a compound annual growth rate of 20.7 percent.

NetScout (Formerly is Fluke) , Viavi (formerly is JDSU) and Riverbed are leaders in the Gartner NPMD Magic Quadrant for the fourth consecutive year. 

Gartner Magic Quadrant for Data Center Infrastructure Management (DCIM) (2016, 2015,2014)

Data center infrastructure management (DCIM) tools monitor, measure, manage and/or control data center resources and energy consumption of both IT-related equipment (such as servers, storage and network switches) and facilities infrastructure components (such as power distribution units [PDUs] and computer room air conditioners).

Based on Gartner report on Oct 2016, Nlyte Software, Emerson Network Power, and Schneider Electric continue to lead in the DCIM software market.

Gartner Magic Quadrant for DCIM, Oct 2016

Friday, April 7, 2017

Avocent® ACS 8000 Advanced Console System Configuration

My company has used Avocent ACS (Advanced Console Server) to do network devices' console management for many years already. I were using 4000, 5000 and 6000 serie, and now 8000 series is coming to refresh some old ones. The basic steps and commands are same for all those three types of ACS hardware.

Emerson (EMR) acquired infrastructure management specialist Avocent Corporation (AVCT) for $1.2 billion on Oct 2009. Since then Emerson combined its Aperture and new Avocent businesses as a new division focused on helping data center customers better manage their infrastructure. Now it is part of Vertiv which launched as standalone business. The Vertiv's Trellis DCIM platform was the first to use real-time data to enhance data center management and has been recognized as a leader in every DCIM Magic Quadrant published by Gartner.

Interesting thing is I even could not find Avocent product from Vertiv's product page. Totally there are 13 products under IT management category, but ACS product line is not there. I managed to google and find one link which shows more this product at this link:

Emerson Avocent ACS8000 Front

Thursday, March 30, 2017

Brocade Switch Access Through SSH and Web Tools

1. Through SSH
It is pretty straightforward, launch ssh client, enter your switch ip and credential, you will be in the command line.

Saturday, February 25, 2017

Gartner Magic Quadrant for WAN Optimization (2016, 2015, 2014, 2013, 2012, 2011)

WAN optimization provides a range of features to: (1) improve the performance of applications running across the WAN; and (2) reduce the cost of the WAN. The range and scope of features supported by
WAN optimization solutions continue to evolve, typically in support of three high-level needs:
  • Improve the response times as experienced by users of business-critical applications over WAN links or mobile connections, often addressing application performance problems caused by bandwidth constraints, latency or protocol limitations.
  • Assist in maximizing the ROI for WAN bandwidth, and delay costly bandwidth upgrades.
  • Optimize data-center-to-data-center (DC-to-DC) traffic for faster replication and synchronization.

Gartner Magic Quadrant for Application Delivery Controllers (2016, 2015,2014,2013,2012,2010)

Application delivery controllers (ADCs) are generally deployed in the data center and provide functions that optimize delivery of enterprise applications across the network. ADCs provide functionality for both user-to-application and application-to-application traffic. The ADC effectively bridges the gap between the application and underlying protocols and the traditional packet-based networks. The market evolved from load-balancing systems that were developed in the latter half of the 1990s to ensure the availability and scalability of websites. Enterprises use ADCs today to improve the following aspects of their applications:
  • Availability
  • Scalability
  • End-user performance
  • Data center resource utilization
  • Security
F5 Networks Named a Leader in Gartner Magic Quadrant for Application Delivery Controllers for 10th Consecutive Year
Citrix: Recognized as a Gartner ADC Magic Quadrant Leader for 10 years

Friday, November 4, 2016

Infoblox NetMRI 1400 Appliance with Network Automation OS Configuration Steps

The Infoblox NT 1400 network automation appliance is designed to automate network change, see the impact of changes on network health, manage network configurations and meet a variety of compliance requirements.

  • Network Discovery
Automatically and continually track multi-vendor infrastructure, end hosts, network constructs (routes, VLANs, virtual forwarding and routing, etc.), and topologies with current and historical information.
  • Configuration Management
Automatically detect and audit network changes and receive detailed analysis. Take advantage of configuration back up, powerful search, and correlation of network problems with time and location.
  • Change Automation
Manage network-wide change tasks with simple yet robust methods for encoding change logic with minimal scripting.
  • Policy and Compliance Enforcement
Automatically and continuously assess network changes in real time against security policies with an easy-to-use rule studio.
  • Network Analysis
Get analysis and alerts on network configuration problems, including ticking time bombs that show no fault or performance symptoms.
  • Anytime, Anywhere Mobile Access
Manage your network from your mobile device. View network inventory, find device locations, and control port and VLAN connections.
  • Hardened Appliance
Get a solution that ships on a purpose-built hardware device and includes the operating system and database, reducing your costs and maintenance requirements.

 Infoblox NT 1400 network automation appliance

Monday, October 24, 2016

Gartner Magic Quadrant for Cloud-Enabled Managed Hosting, North America (2015, 2014)

Cloud-Enabled Managed Hosting Market Definition/Description

The cloud-enabled managed hosting (CEMH) market deals in standardized, productized hosting offerings that combine a cloud-enabled system infrastructure (CESI) platform — comprising compute, network and storage hardware owned and operated by a service provider — with cloud management platform software to facilitate self-service and rapid provisioning with managed services (see "Technology Overview for Cloud-Enabled System Infrastructure" note that this document has been archived; some of its content may not reflect current conditions ). The infrastructure platform may be located in a service provider's data center, or optionally at the customer's data center, but, either way, it requires standardized deployment across all customers and uses a single code base that has been pre-engineered and/or predeployed by the provider prior to customer sign-up. At minimum, a service provider must supply server OS management services, including guest OS instances when virtualization is used. The provider may optionally supply other managed and professional services relating to the infrastructure's deployment and operation.
Cloud-enabled managed hosting allows only limited customization. It is sold on a stand-alone basis, with no requirement to bundle it with — for example — application development, application maintenance or data center outsourcing (DCO) services.
Customers must be able to access a self-service interface, which may be different from the platform interfaces used internally by the provider. A service provider can potentially intervene in the self-service workflow to manually approve, deny or alter a customer's requests, as long as the provisioning requested is fulfilled in a fully automated manner thereafter. Managed services (such as OS backups, patching and monitoring) must be available to customers on commitments of less than one year.

Thursday, March 24, 2016

Mobile Iron Sentry VM Installation

What is Mobile Iron Sentry?

Mobile Iron Centry provides access control for email. Sentry connects to Microsoft ActiveSync-enabled email systems such as Microsoft Exchange, IBM Lotus Notes, Google Gmail, and Microsoft Office 365. MobileIron Sentry  is an in-line gateway that manages, encrypts, and secures traffic between the mobile device and back-end enterprise systems. Like the VSP, it may be deployed as a physical hardware appliance or a virtual appliance using VMware ESX. Mobile Iron Sentry is included in the Mobile Iron Advanced Management package, though the hardware appliance is sold separately.

MobileIron's [email protected] App connects your Android device to your company network so that you can easily and securely access email and other work resources. [email protected] App works in conjunction with a MobileIron Core server deployed by your company’s IT organization. .

In this post, I am using sentry-mobileiron-7.0.1-29.iso to do installation into Vmware Workstation 10.


Saturday, November 28, 2015

Updating InfoBlox Network Automation Product NetMRI

Infoblox NetMRI product  has been really helpful to manage network environment. The post Use Network Automation Tool Infoblox NetMRI Push Configuration to Multiple Network Devices explains how to do a batch job with some clicks. This post will explain how to update NetMRI product with some learned experience.

There are two methods to update NetMRI software:

1. Automatic Update

Friday, October 16, 2015

Use Network Automation Tool Infoblox NetMRI Push Configuration to Multiple Network Devices

Infoblox NetMRI Appliance
For those still do not know what is Infoblox NetMRI product, here is some simple introduction. Actually it can do more than what normal network administrators think.

NetMRI is one of the most important products owned by Infoblox. This product came with the acquisition of Netcordia in 2010. NetMRI provides automatic network discovery, switch port management, network change automation and continuous configuration compliance management for multi-vendor routers, switches and other layer 2 and 3 network devices. NetMRI helps customers move from out-of-date spreadsheets, error-prone manual processes like scripts and CLI access and ad hoc audit teams.

Sunday, August 16, 2015

Layer 2 / Layer 3 IP Packets Switching Procedures

Layer 2 Packets Switching Procedures

The packet will be sent in the same vlan.

1. A sends ARP -who is
Destination MAC address : ALL FF's
Source MAC address: A1

2. ARP is broadcast so switch forwards out all ports

3. B replies to ARP
Destination MAC:A1
Source MAC: B1

4. A sends to B
Destination MAC: B1
Source MAC: A1
Destination IP address:
Souce IP:

5. Switch performs CAM lookup using destination mac address and forwards packet to B1.


Layer 2 / Layer3 IP Switching Procedures

Packets will send from A to D across multiple vlans:

1. A sends ARP - who is
Destination MAC address : ALL FF's
Source MAC address: A1

2. Switch replies to ARP - saying send it to me

3. A sends to Switch
Destination MAC: C1
Source MAC: A1
Destination IP:
Souce IP:

4.Switch does a L3 lookup 

5. Packet forwarded
Destination MAC: D1
Souce MAC: C3
Destination IP:
Source IP:

6. Switch does a forwarding lookup

7: Packet forwarded
Destination MAC: F2
Source MAC: D2
Destination IP:
Souce IP:

Monday, March 16, 2015

Linux Service Configuration - NTP

As a network guy, you will work with NTP (Network Time Protocol) lots for your network devices.

From Wikipedia, the explanation regarding NTP is:
"The protocol is usually described in terms of a client-server model, but can as easily be used in peer-to-peer relationships where both peers consider the other to be a potential time source.Implementations send and receive timestamps using the User Datagram Protocol (UDP) on port number 123. They can also use broadcasting or multicasting, where clients passively listen to time updates after an initial round-trip calibrating exchange. NTP supplies a warning of any impending leap second adjustment, but no information about local time zones or daylight saving time is transmitted."
A local linux NTP server on the network can be synchronized with a trusted timing source to keep all of your internal NTP clients in sync with an accurate time. For windows ntp server, please check my previous post: Build NTP Windows Server for Network Devices (not Win32Time)

1. Install NTP Server

a. Check your linux release

[[email protected] ~]# cat /etc/redhat-release
CentOS release 6.6 (Final)

b. [[email protected] ~]# yum install ntp

Loaded plugins: fastestmirror
Setting up Install Process
Loading mirror speeds from cached hostfile
Package ntp-4.2.6p5-2.el6.centos.x86_64 already installed and latest version
Nothing to do

2. Modify /etc/ntp.conf

a. add trusted time server, in my case it is Other configuration could be default. 

b. Restart ntpd service

[[email protected] ~]# service ntpd restartShutting down ntpd: [  OK  ]Starting ntpd: [  OK  ][[email protected] ~]# service ntpd stopShutting down ntpd: [  OK  ][[email protected] ~]# service ntpd startStarting ntpd: [  OK  ]

c. Also you could restrict only specific clients

restrict mask nomodify notrap

d. add local clock as backup

server # local clockfudge stratum 10

3. Verify NTP Status

a. using command ntpq -p
[[email protected] ~]# ntpq -p     remote           refid      st t when poll reach   delay   offset  jitter==============================================================================*   3 u   25   64  377    2.173    4.430   3.906

b. Manually synchronize time

[[email protected] ~]# ntpdate -u Mar 20:38:58 ntpdate[2671]: adjust time server offset -0.005387 sec

c. on your linux NTP client, you could start your ntp client Daemon and check the ntp client status

[[email protected] ~]# /etc/init.d/ntpd start
Starting ntpd:  
[[email protected] ~]# ntpdc -c sysinfo
system peer:          r-1-hsrp.mgmt.intern
system peer mode:     client
leap indicator:       00
stratum:              4
precision:            -19
root distance:        0.18851 s
root dispersion:      1.09599 s
reference ID:         []
reference time:       d8b1b105.8e2ff185  Mon, Mar 16 2015 20:44:05.555
system flags:         auth monitor ntp kernel stats
jitter:               0.000000 s
stability:            0.000 ppm
broadcastdelay:       0.000000 s
authdelay:            0.000000 s
[[email protected] ~]# service ntpd status
ntpd (pid  28807) is running...
[[email protected] ~]# chkconfig --list
abrt-ccpp       0:off   1:off   2:off   3:on    4:off   5:on    6:off
abrt-oops       0:off   1:off   2:off   3:on    4:off   5:on    6:off
abrtd           0:off   1:off   2:off   3:off   4:off   5:off   6:off
acpid           0:off   1:off   2:on    3:on    4:on    5:on    6:off
atd             0:off   1:off   2:off   3:off   4:off   5:off   6:off
auditd          0:off   1:off   2:on    3:on    4:on    5:on    6:off
autofs          0:off   1:off   2:off   3:off   4:off   5:off   6:off
avahi-daemon    0:off   1:off   2:off   3:on    4:on    5:on    6:off
blk-availability        0:off   1:on    2:on    3:on    4:on    5:on    6:off
certmonger      0:off   1:off   2:off   3:off   4:off   5:off   6:off
cgconfig        0:off   1:off   2:off   3:off   4:off   5:off   6:off
cgred           0:off   1:off   2:off   3:off   4:off   5:off   6:off
chronyd         0:off   1:off   2:off   3:off   4:off   5:off   6:off
cpuspeed        0:off   1:on    2:off   3:off   4:off   5:off   6:off
crond           0:off   1:off   2:on    3:on    4:on    5:on    6:off
cups            0:off   1:off   2:on    3:on    4:on    5:on    6:off
dnsmasq         0:off   1:off   2:off   3:off   4:off   5:off   6:off
dsmc            0:off   1:off   2:off   3:off   4:off   5:off   6:off
ebtables        0:off   1:off   2:off   3:off   4:off   5:off   6:off
fusioninventory-agent   0:off   1:off   2:off   3:off   4:off   5:off   6:off
haldaemon       0:off   1:off   2:off   3:on    4:on    5:on    6:off
htcacheclean    0:off   1:off   2:off   3:off   4:off   5:off   6:off
httpd           0:off   1:off   2:off   3:off   4:off   5:off   6:off
ip6tables       0:off   1:off   2:off   3:off   4:off   5:off   6:off
iptables        0:off   1:off   2:off   3:off   4:off   5:off   6:off
irqbalance      0:off   1:off   2:off   3:on    4:on    5:on    6:off
iscsi           0:off   1:off   2:off   3:off   4:off   5:off   6:off
iscsid          0:off   1:off   2:off   3:off   4:off   5:off   6:off
kdump           0:off   1:off   2:off   3:off   4:off   5:off   6:off
ksm             0:off   1:off   2:off   3:off   4:off   5:off   6:off
ksmtuned        0:off   1:off   2:off   3:off   4:off   5:off   6:off
libvirt-guests  0:off   1:off   2:off   3:off   4:off   5:off   6:off
libvirtd        0:off   1:off   2:off   3:off   4:off   5:off   6:off
lm_sensors      0:off   1:off   2:off   3:off   4:off   5:off   6:off
lvm2-monitor    0:off   1:on    2:off   3:off   4:off   5:off   6:off
mcelogd         0:off   1:off   2:off   3:on    4:off   5:on    6:off
mdmonitor       0:off   1:off   2:off   3:off   4:off   5:off   6:off
messagebus      0:off   1:off   2:on    3:on    4:on    5:on    6:off
netcf-transaction       0:off   1:off   2:on    3:on    4:on    5:on    6:off
netconsole      0:off   1:off   2:off   3:off   4:off   5:off   6:off
netfs           0:off   1:off   2:off   3:off   4:off   5:off   6:off
network         0:off   1:off   2:on    3:on    4:on    5:on    6:off
nfs             0:off   1:off   2:off   3:off   4:off   5:off   6:off
nfslock         0:off   1:off   2:off   3:off   4:off   5:off   6:off
nmb             0:off   1:off   2:off   3:off   4:off   5:off   6:off
nrpe            0:off   1:off   2:on    3:on    4:on    5:on    6:off
nscd            0:off   1:off   2:off   3:off   4:off   5:off   6:off
nslcd           0:off   1:off   2:off   3:off   4:off   5:off   6:off
ntpd            0:off   1:off   2:off   3:off   4:off   5:off   6:off
ntpdate         0:off   1:off   2:off   3:off   4:off   5:off   6:off

numad           0:off   1:off   2:off   3:off   4:off   5:off   6:off
oddjobd         0:off   1:off   2:off   3:off   4:off   5:off   6:off
portreserve     0:off   1:off   2:on    3:on    4:on    5:on    6:off
postfix         0:off   1:off   2:on    3:on    4:on    5:on    6:off
psacct          0:off   1:off   2:off   3:off   4:off   5:off   6:off
quota_nld       0:off   1:off   2:off   3:off   4:off   5:off   6:off
radvd           0:off   1:off   2:off   3:off   4:off   5:off   6:off
rdisc           0:off   1:off   2:off   3:off   4:off   5:off   6:off
restorecond     0:off   1:off   2:off   3:off   4:off   5:off   6:off
rngd            0:off   1:off   2:off   3:off   4:off   5:off   6:off
rpcbind         0:off   1:off   2:off   3:off   4:off   5:off   6:off
rpcgssd         0:off   1:off   2:off   3:off   4:off   5:off   6:off
rpcsvcgssd      0:off   1:off   2:off   3:off   4:off   5:off   6:off
saslauthd       0:off   1:off   2:off   3:off   4:off   5:off   6:off
smartd          0:off   1:off   2:off   3:off   4:off   5:off   6:off
smb             0:off   1:off   2:off   3:off   4:off   5:off   6:off
sshd            0:off   1:off   2:on    3:on    4:on    5:on    6:off
sssd            0:off   1:off   2:off   3:off   4:off   5:off   6:off
svnserve        0:off   1:off   2:off   3:off   4:off   5:off   6:off
syslog-ng       0:off   1:off   2:on    3:on    4:on    5:on    6:off
sysstat         0:off   1:on    2:on    3:on    4:on    5:on    6:off
udev-post       0:off   1:on    2:on    3:on    4:on    5:on    6:off
winbind         0:off   1:off   2:off   3:off   4:off   5:off   6:off
xe-linux-distribution   0:off   1:off   2:on    3:on    4:on    5:on    6:off
ypbind          0:off   1:off   2:off   3:off   4:off   5:off   6:off

[[email protected] ~]# service --status-all | less
auditd is stopped
crond (pid  1087) is running...
dsmc is stopped
dsmcad is stopped
fusioninventory-agent is stopped
ip6tables: Firewall is not running.
Table: filter
Chain INPUT (policy ACCEPT)
num  target     prot opt source               destination        
1    ACCEPT     all  --             state RELATED,ESTABLISHED
2    ACCEPT     icmp --            
3    ACCEPT     all  --            
4    ACCEPT     tcp  --             state NEW tcp dpt:22
5    ACCEPT     tcp  --             state NEW tcp dpt:5666
6    ACCEPT     tcp  --             state NEW tcp dpt:1500
7    ACCEPT     tcp  --             state NEW tcp dpt:1501
8    REJECT     all  --             reject-with icmp-host-prohibited
Chain FORWARD (policy ACCEPT)
num  target     prot opt source               destination        
1    REJECT     all  --             reject-with icmp-host-prohibited
Chain OUTPUT (policy ACCEPT)
num  target     prot opt source               destination        
ktune settings are not applied.
No sensors found!
Make sure you loaded all the kernel drivers you need.
Try sensors-detect to find out which these are.
lvmetad is stopped
messagebus (pid  863) is running...
netconsole module not loaded
Configured devices:
lo eth0
Currently active devices:
lo eth0
nrpe (pid  973) is running...
nscd is stopped
nslcd is stopped
ntpd (pid  961) is running...
master (pid  1071) is running...
Process accounting is disabled.
qpidd is stopped
rdisc is stopped
rpcbind (pid  804) is running...
rsyslogd (pid  778) is running...
sandbox is stopped
saslauthd is stopped
openssh-daemon (pid  932) is running...
syslog-ng is stopped
tuned is stopped
winbindd is stopped
os_name="CentOS release 6.6 (Final)"

[[email protected] ~]# netstat -tulpn
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address               Foreign Address             State       PID/Program name  
tcp        0      0        *                   LISTEN      932/sshd          
tcp        0      0      *                   LISTEN      1071/master        
tcp        0      0      *                   LISTEN      973/nrpe          
tcp        0      0       *                   LISTEN      804/rpcbind        
udp        0      0       *                               804/rpcbind        
udp        0      0       *                               804/rpcbind        
udp        0      0  *                               961/ntpd          
udp        0      0     *                               961/ntpd          
udp        0      0       *                               961/ntpd            

Sunday, March 1, 2015

Bridge Your Home Routers to Extend Your Wireless Network

Not sure how many home users are experiencing wireless router coverage issue. Your wireless home router is set at living room, but at the certain location of your home, the wireless signal is quite weak. It will be painful especially when you found this fact on the bed with your tablet devices. Upgrade a more powerful wireless routers, or buy another router repeater?Actually the router vendors have implemented a "bridge" technology which can enable wireless connection between multi-vendor's routers. Here is Wikepedia's explanation about Bridging (networking):
"Network bridging is the action taken by network equipment to create an aggregate network from either two or more communication networks, or two or more network segments. If one or more segments of the bridged network are wireless, it is known as wireless bridging. Bridging is distinct from routing, which allows multiple different networks to communicate independently while remaining separate."
This post is my weekend task to get my living room's wireless signal to cover the corner of my bed room better. In the bedroom's far end from wireless router's location, the signal is always not enough to keep my ipad/cell phone persistently connected. To stop my family's complain, I decided to set up secondary router as a bridge Access Point at second floor, which will provide strong signal to upper floors.


1. Main Router's Configuration

Main router is from isp, and this Adsl device model is HG-A800. This router's configuration is not any special. You just need to enable wireless security, LAN network and DHCP. 

Wireless basic configuration:

Note: Channel should not be set to Auto since it may change after a reboot or power outage. After you find out current channel number such as 6 in this example, you will need to set it as current channel. Your bridge channel will be set it to same number manually. That will prevent lost connection between two routers. (updated Jul 12 2017)

 Wireless Security:

 LAN and DHCP Setup (LAN IP is

2. Secondary Router's Configuration:

TP-LINK WR941ND is used as secondary router for bridge Access Point purpose. 

There is no connection on WAN port since it is secondary router which is not directly connecting to Internet. LAN port can be used to connect local network devices such as media player, game console or desktop.WAN configuration type for this secondary router will be Dynamic IP. LAN IP will be DHCP Scope is from to As you tell, The DHCP Scope of Primary router and Secondary router is not overlapping, which is easier for us to identify which device your system is logged in by wireless later. 

The most important part is Wireless Settings in secondary router. You had better set up same wireless SSID and password  as Primary router, especially at SSID (to be bridged) section. 

Note. As you can see the channel is manually set to 6 to match your main router. 

3. Test Result

My ISP is providing 15 mbps downloading speed and 1 mbps uploading speed. From the's result, it shows pretty good result from Secondary router, almost no loss from this set up.