Basic OS recognition

ping -c 1 10.10.10.10
# TTL = 64 -> Linux
# TTL = 128 -> Windows
# TTL = 256 -> Solaris
# If the TTL number doesn't correspond to any of those, you can try to do the next
traceroute 10.10.10.10
# And sum the restult of the TTL with the number of hops.
# I.e: 53 (TTL)+ 11(Number of hops) = 64 -> Linux