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Feb 26, 2010 No Comments
If you like to find out which VLAN is being used on your switches, an very useful IOS command is “show vlan counters”. Its output will tell you whether you can delete a VLAN from your switches. cat63#sh vlan counters * Multicast counters include broadcast packets Vlan Id [...]
Read more...Feb 23, 2010 No Comments
Just receive a brand new Cisco ASR 1002-F. Here are some pictures of the box: ASR 1002-F Power Supply: DS3 Line SPA:
Read more...Feb 15, 2010 No Comments
Kim Zetter from Wired magazined did an article on the recently Google being hacked incident. A new acronym to know: APT – Advanced Persistence Threats
Read more...This whitepaper includes a list a really nice DNS troubleshooting tools: http://www.cisco.com/web/about/security/intelligence/dns-bcp.html
Read more...Feb 10, 2010 No Comments
You probably have more than one DNS server listed in your Linux resolv.conf file. However if you notice your system would slow down when one of the DNS servers went off line, it is because if your applications resolve PTR record, it would send out a PTR record to the first DNS server on the [...]
Read more...Ever experience your Microsoft Windows server lost connectivity after an reboot? You can want to check the host’s default gateway. The is a bug in Windows, that could cause TCP/IP stack corruption. When that happens, Windows host would lose its default gateway after a reboot. Here is the Microsoft knowledge base: http://support.microsoft.com/kb/299357 The fix is [...]
Read more...Feb 4, 2010 No Comments
I ran into a Cisco FWSM issue today. No changes have been made, I verified the access list, it allows the traffic to pass through, check asp drop by using “show asp drop”, there is no asp drop. I can see packets entered FWSM, but the packets got dropped by FWSM, and there is no [...]
Read more...Jan 12, 2010 No Comments
Many people, particularly IT auditors, and less technical folks have concerns when internal IP addresses are “exposed” to the Internet, they will face a big surprise when they learn that NAT is not supported in IPv6. You can point them to this IPv6 Local Network Protection article by Cisco, hopefully it will clarified some of [...]
Read more...Jan 11, 2010 No Comments
Network admins frequently has stressful network throughput between two hosts. One of the best free tools for this purpose is iperf developed by NLANR. You can tweak many TCP and UDP settings to test the max throughput between two hosts. You can find iperf on Sourceforge, however only the source code is available.
Read more...Dec 31, 2009 No Comments
If you need a SSL cert and don’t have a PKI infratructure, or just do not like to remember those long and complex openssl syntax, there is an option, COMODO offers FREE SSL Cert for 90 days, and their CA cert is included in most browsers.
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