There is a limit on the number of concurrent socket connections that an application can accept in BSD, Windows, and other operating systems. This is set at compile time, but it can be overridden. Here is a discussion of this limitation by Microsoft, and here is further discussion. One application that is sticking this on […]

Here is a text version of /etc/services that might be useful for determining whether a port is being used by a trojan, etc: TCP and UDP Service Listing

Here is our subnet reference guide and The Perl script used to generate it If you want an easy to use subnetting calculator, Subnet-Calculator.org is one of the best ones we’ve seen online. Subnet Reference Guide — Value of individual bits in an eight bit byte if true: Bit 7 = 128 Bit 6 = […]

If you have a WAN, then one very important concern should be latency. Latency, in this case, is the time that a package of information takes to reach the other end of the slow link. This package of information could be a DNS query, ping, file, or a transaction in a client/server application. Notice that […]

There are some nasty, nasty SNMP vulnerabilities that have recently been revealed. Many different products are affected. See the CERT Advisory Here. This inspired us to upgrade our Cisco. To upgrade the IOS on your Cisco router, you have a couple of options. You can either upgrade via TFTP, or you can use the console. […]