Tag Archives: protocol

Using Ping Sweep to Find MTU Ceiling

Earlier this week I had breakfast with a very interesting group. One of those present had an extensive history with Cisco systems. We talked about his tenure and several of the projects that he had been involved in. For some … Continue reading

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Classic IOS as a DNS Server

There is an occasional need for a DNS server in the absence of a dedicated host. This may occur in the following situations– Using PAT, Public DNS may return a non-RFC1918 address for internal server Lab/Demo Environment Other Name Resolution challenges in SOHO, … Continue reading

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Don’t Forget about the ASA’s “show conn” Command

I often find myself troubleshooting connections through an ASA. As a firewall, the ASA is often blamed for network connectivity issues. Therefore, we often just want to determine if the issue is upstream or downstream from the firewall. One of … Continue reading

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MSCHAPv2, Not So Secure…

I wanted to call attention to some research done by Moxy Marlinspike in the are of MSCHAPv2. This protocol is used in PPTP and many enterprise wireless environments. The article below explains how theory behind cracking the handshake and de-obfuscating … Continue reading

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Protecting Insecure Protocols

Last week I wrote an article that demonstrated the grievous security oversight in the Telnet protocol. Telnet, being a clear text protocol, exposes the entire contents of any session to anyone who can gain access to the traffic. Telnet is … Continue reading

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What’s Wrong With Telnet?

We have all heard that telnet is bad. We have heard that it is an insecure protocol that sends information in clear text. Conceptually, that sounds simple. However, let’s take a look at what this really means. To demonstrate what … Continue reading

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The Future of the OSI Model

The OSI model is that thing that everyone seems to love to hate. The OSI is actually just a model that has its roots in the International Organization for Standardization. We’ve all had disagreements how certain protocols map to certain … Continue reading

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