Could this be more readable? Do we need to match IP addresses with ```\s+(\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})``` or could we match on something simpler? Perhaps move those into local variables and use string interpolation to make the regex more clear.

```
r_interface_name = "([0-9a-zA-Z\.\:\-]+)"
r_ip_address = "(\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})"
r_mac_address = "([a-fA-F0-9\:]+)"
if line =~ /^#{r_interface_name}\s+#{r_ip_address}\s+#{r_ip_address}\s+([SPLA]+)?\s+#{r_mac_address}/
```

Thoughts?