We feature technical articles across the entire IT spectrum - Networking, security, operating systems, cloud, and programming.

IPv4 Subnetting Notes

The other day someone asked me to explain subnetting. It had been a while so I dusted off my CCNA books and attempted to answer his questions. So I thought this would be an ideal time to jot down some notes for future reference. This isnt a tutorial or guide but just some some notes … Read more

Types of IDS Alerts

There are 4 main types of IDS alerts. These are :  True Positive Bad traffic which triggers an alert.  False Positive Good traffic which triggers an alert. False Negative Bad traffic, but no alert is raised. True Negative Good traffic, and no alert is raised.

How to run vSphere using SSH tunnelling

This guide looks at running your vSphere Client through SSH tunnels. You may need to do this due to having a Proxy in place or your firewall is blocking the required ports you need in order to run vSphere. 1. First of all edit your hosts file to include an entry for you ESX box. … Read more

Compiling Rancid on an x86 Solaris 10 platform

Below shows you the steps in order to compile Rancid on an x86 Solaris 10 platform. RANCID monitors a router’s (or more generally a device’s) configuration, including software and hardware (cards, serial numbers, etc) and uses CVS or Subversion to maintain history of changes. Space on /var If you havent much space on /var run … Read more

How to secure your Cisco Catalyst switch

Below is a guide to the main areas and features that you should be aware of to ensure that your Cisco Catalyst switch is fully secured within your network. 1. PASSWORDS First of all passwords are configured. One password is used for the enable password and the other will later be assigned to the console … Read more

Solaris 10 x86 – Error compiling from source

When compiling from source you may see the following errors occur :    /usr/include/sys/siginfo.h:259: error: parse error before “ctid_t”   /usr/include/sys/siginfo.h:292: error: parse error before ‘}’ token   /usr/include/sys/siginfo.h:294: error: parse error before ‘}’ token    /usr/include/sys/siginfo.h:390: error: parse error before “ctid_t”   /usr/include/sys/siginfo.h:392: error: conflicting types for `__proc’   /usr/include/sys/siginfo.h:261: error: previous declaration of `__proc’   /usr/include/sys/siginfo.h:398: error: conflicting … Read more

Solaris Compile configure: error: no acceptable grep could be found in

When compiling programs in Solaris you may find you recieve the following error (or something along the same lines) complaining about grep. checking for grep that handles long lines and -e… ./configure: line 3859: 13085 Killed “$ac_path_GREP” -e ‘GREP$’ -e ‘-(cannot match)-‘ <“conftest.nl” >”conftest.out” 2>/dev/null ./configure: line 3859: 13092 Killed                  “$ac_path_GREP” -e ‘GREP$’ -e ‘-(cannot … Read more

What are reflective access-lists ?

Reflective access-lists allows the router to pass “established” tcp traffic that has been previously allowed via another ACL. Due to routers to not having (by default) a state table, this ensures that you do not have to create additional access list entries to allow the return traffic of a permitted tcp session. (config)# ip access-list … Read more

Securing your IOS configuration and files

In a worst case scenario someone could gain access to your router, clear the boot image and config. This would result in a lengthy down time and a lot stress. Cisco have tried to address this but the use of the following commands which prevents the clearing of your config and boot image (config) # … Read more

Solaris GCC Failure: errno 28, No space left on device

When trying to install the gcc package on Solaris you may find you get the following error : cpio: Cannot write “reloc/lib/gcc-lib/i386-pc-solaris2.10/3.3.2/cc1obj”, errno 28, No space left on device cpio: Cannot write “reloc/lib/gcc-lib/i386-pc-solaris2.10/3.3.2/cc1plus”, errno 28, No space left on device cpio: Cannot write “reloc/lib/gcc-lib/i386-pc-solaris2.10/3.3.2/collect2”, errno 28, No space left on device cpio: Cannot write “reloc/lib/gcc-lib/i386-pc-solaris2.10/3.3.2/f771”, … Read more