Other Basic Tools

traceroute

enables the network manager to discover the route taken by IP datagrams in travelling to a remote host.

netstat

gives information about the UNIX kernel data structures associated with TCP/IP. For example, netstat -r prints the kernel routing table, whilst netstat -a reports on all current TCP activity.

arp

reports on all current Address Resolution Protocol (IP to MAC layer mappings) information. Can be very useful where Proxy-ARP is in use!

nslookup, dig

useful for checking DNS (Name Service) operation. Note that if DNS is not operational, other tools may still be usable with dotted IP addresses instead of names.

telnet

useful for checking operation of the TCP sub-system. In addition, many network devices (eg, most routers) support telnet connection by the network manager to check loads, error rates, etc.

finger

may be useful to check for existence of this basic TCP service, also to check for excessive system loads on remote machines.