Not so often we would end up troubleshooting or manipulating ARP and ARP tables in Sun Solaris. However, following are some of the useful commands which can help when required. The following commands will help you display,modify,add,delete ARP entries in Sun Solaris ARP table.
ARP attacks are the easiest attacks that can be launched on a network or a Server causing a Denial of Service. One of those things that can be done on the Sun Solaris Operating System is to alter the caching time for the ARP cache whch reduces the time that a rogue ARP entry stays in the ARP table. While this is not fool proof but can certainly make it that extra difficult to the hacker.
The default time that ARP entries are cached in a Sun Solaris system is 5 mins.
The nscd daemon is a caching daemon in Sun Solaris. It provides caching services for hosts,passwd,group,ipnodes databases using various nameservice lookups like hosts file, DNS, NIS,NIS+ and more. Each cache has a separate time-to-live for its data and modifying the local database like /etc/hosts invalidates that cache within ten seconds. nscd doesn’t cache /etc/shadow (contains encrypted passwords for /etc/passwd) file simple for security reasons as anyone would understand.
As nscd daemon provides caching service, it is necessary when you run a name service like DNS, NIS or NIS+ in your network. The configuration of nscd daemon can customised using the /etc/nscd.conf file and it is important more from a security point of view where you can control what is and how is cached on your solaris server.
It may be sometime required to flush your DNS Cache mostly when trying to troubleshoot a problem with your name service or when there was an invalid DNS entry after a server outage. The possible solution to clear these cached invalid entries or to wait till the record expires based on its TTL (Time To Live)