The first 0.6 miles of the approach crosses private land that has a conservation easement currently. Be respectful, stay on the trail and don't leave trash. After the 0.6 miles you're on Forest Service land (there is a sign).
This information is a public crowdsourcing effort between the Access Fund,
and Mountain Project. You should confirm closures, restrictions, and/or related dates.
Scott Salzer on the last pitch of the first ascent...
Frog Rock is the most obvious big chunk of limestone that can be seen from Bozeman, towering over Bozeman Pass on the south side of I-90. For years there were major access issues which have been resolved as long as folks are respectful and follow the signage. The rock is Madison limestone/dolomite outcropping here in features up to 400' high. Pockets abound from shallow dish monos to huge incut huecos. Routes clean up well with a bit of scrubbing and traffic. There are sunny routes, shady routes and most in-between. This area is a bit higher and much of the hillside is north facing, so is nice and cool generally. The only print guide is Dockins', which doesn't cover the newer routes around Servus, so chances are you'll not have too much company.
Take the Trail Creek Exit off I-90 (west of Bozeman Pass proper). Once on the south side of the interstate, go east to the Chestnut Mountain parking lot (~1/4 mile from the exit). The trail crosses private property for 0.6 miles, then take a right after another 0.6 miles at a signed post, then another 0.9 miles to the main area (~2.1 miles each way).
Mountain Project's determination of some of the classic, most popular, highest rated routes for Frog Rock: