Raymond Etornam - Posts - About

View Routing Table on OS X and Linux

On Linux, the route command shows and manipulates the IP routing table. To view the full route table, use the command route -n.The -n flag according to the man pages:

show numerical addresses instead of trying to determine symbolic
host names. This is useful if you are trying to determine why the
route to your nameserver has vanished.

In much simpler language, the -n flag resolves IP addresses to their hostnames.

For example the destination default displays if you pass the -n flag and default without it.

OS X on the other hand has the route command but can only manually manipulate the routing tables and doesn’t show the table like on Linux.For this reason, I often use the netstat command instead and prefer netstat -nr

The -n flag on OS X according to the man page:

shows network addresses as numbers (normally netstat interprets addresses and
attempts to display them symbolically).  
This option may be used with any of the display formats

The r flag according to the man page:

show the routing tables.  Use with -a to show protocol-cloned routes.  
When -s is also present, show routing statistics instead.  
When -l is also present, netstat assumes more columns are there and the
maximum transmission unit.  More detailed information about the route metrics 
are displayed with -ll for TCP round trip times -lll for all metrics.  
Use the -z flags to display only entries with non-zero RTT values.  (''mtu'') 
are also displayed.

As always, it is good to spend time reading the man pages to understand the flags available for each command and how to use them properly.

Hope this helps