Investigating Linux Network Issues with netstat and nstat

One area that I’ve been spending quite a bit of time looking at lately is the TCP layer on our servers.  We have seen multiple issues that involve TCP and it is an oft-overlooked area when troubleshooting.

There are two tools that I’d like to focus on today – netstat and nstat.  Both tools pull statistics from the following Linux files, which track network-related statistics and SNMP counters:

/proc/net/netstat
/proc/net/snmp

Here is what the output of these two files looks like:

Continue reading