German Shepherd Rottweiler Mix?

by Nina
(Kansas City, MO)

I adopted my dog two months ago from a shelter where he was listed as "shepherd mix". We want to know what he's mixed with. We've been guessing Rottweiler? Here is a link to some photos:

s1240.photobucket.com

He is very, very sweet to us, but aggressive towards strangers and other dogs. He loves being outside, and tends to run away (ten times in two months!) He's very smart, we've been able to teach him sit, stay, shake and he's learning lay down.

What do you guys think??