Build NTP Windows Server for Network Devices (not Win32Time)
Based on Cisco Document (ID108076) Troubelshoot Network Time Protocol (NTP), Cisco devices are not able to Sync NTP to W32 Based Time Service. “Windows W32Time shows that it is an…
GNS3 VoIP Lab (Cisco 3725 and CME 4.3)
Here is a simple VoIP Lab in GNS3 environment. It is only used for my lab test and recorded here for future reference. 1. Topology: GNS3 Topology: Logic Topology: xp(192.168.2.60)——–C3725…
Gartner Magic Quadrant for User Authentication (2014, 2013, 2012)
The Magic Quadrant for User Authentication depicts Gartner’s independent analysis of authentication vendors in the marketplace. Positioning within the quadrant is based on an organization’s ability to execute and completeness…
OpenWRT in Vmware as a light weight router and virtual host
OpenWrt is a Linux distribution for embedded devices and provides a fully writable filesystem with package management. Also for me, it is perfect for running OpenWRT as a small router…
FTP Active mode vs Passive Mode
Traffic flow for Active mode and Passive mode: 1. Active FTP : command : client >1023 -> server 21 data : client >1023 <- server 20Running ftp command from client…
Understanding TCPDUMP Output
These examples in this post bases on Checkpoint Firewalls. In other platform, the output and command options may have a difference. Basic TCPDUMP Commands: tcpdump port 257 , <– on…
GNS3 V1.0 Alpha for Linux in Vmware Workstation
Some Exciting GDS3 V1.0 Alpha feature from their website page, especially IOU Switching Support: Alpha 2 Release – 16/04/14 New Dynamips IOS Support Easy Idle PC Calculation and Configuration IOS…
Basic MPLS Lab on GNS3
Topology: IOS: c3640-jk9s-mz.124-16.bin GNS3 IOS Configuration: Changed XTERM to gnome-terminal for better copy&paste feature: In GNS3 Preference , replaced xterm -T %d -e ‘telnet %h %p’ >/dev/null 2>&1 & with…
Cisco MPLS IOS for GNS3
Here are listed working IOS for MPLS LAB on GNS3: c3640-jk9s-mz.124-16 c3640-jk9s-mz.124-16a c3640-jk9o3s-mz.123-14.T7 c7200-adventerprisek9-mz.124-11.T c3725-adventerprisek9-mz.124-15.T10 Note: c3640-jk9s-mz.124-16是学习Gisco过程中最我们最常用IOS,此IOS不单单支持路由交换实验，同时还支持IPv6、VPN、VOip、MPLS-VPN 等，所以人们通常称之为全能型IOS。
Check Cisco Device Interface Throughput with load-interval Command
BGP_1#sh int g0/1 GigabitEthernet0/1 is up, line protocol is up Hardware is iGbE, address is e02f.6d05.c401 (bia e02f.6d05.c401) Internet address is 6.99.9.30/32 MTU 1500 bytes, BW 1000000 Kbit/sec, DLY 10…
VRRP and Object Tracking
Having following requirements to configure First Hop Redundancy Protocol for one environment:1. Use least public ip addresses2. Track Internet facing interface and BGP routes3. Primary router is high priority and…
Why Cisco Devices refused SSH connection
Network devices usually managed through SSH services. Sometimes, those devices lost SSH access with” The remote system refused the connection.” error message presenting on the SSH client such as SecureCRT.…