required connections for a srcds

[sinister3vil]

Hello,

I was wondering what are the required connections for a fully working srcds, specifically CS:GO.

To further elaborate : Appart from the obvious 27015 (or whater you set) UDP connection to let people play on the server what else is needed?
Obviously srcds needs to connect to the Steam master servers to advertise the server. Does it also connect to Steam to authenticate? Does VAC require a connection to Steam to report bans and/or update its current definitions? Does it require a connection to Steam for community features like achievements or statistics? Are these connections over TCP or UDP?

[Ghost Assassin]

You just need port 27015 (UDP/TCP) to be open for the csgo server to be seen online.

Internet connection is required for all of those features you listed. I'm pretty sure you can disable VAC if you wanted to on the server.

[sinister3vil]

Obviously an Internet connection is required, I'm asking for specifics.
For example, "you need TCP port 27000 for VAC", that kind of thing.

At the very least I need to know if :
-all traffic appart from the game traffic is TCP, and
-when advertised on the master server, does it say "server running here" or "server running on ip:port given in the srcds"?

edit: Maybe I should elaborate on the specifics of my case :

We have 2 subnets, lets say a.b.c.x and a.b.d.x.
a.b.c.x is fully networkable. a.b.d.x will only route towards local (in the same country) destinations. Any traffic towards foreign IPs is null-routed.
Scrds will be running on d.x, for more than one reasons, and will only be accessed by local players by design. I need these srcds to be fully working though, with VAC, community features, the works. Being able to update directly would also be great.
I can't put scrds on c.x nor can I change d.x's null-route policy. What I can do is route specific traffic from d.x through c.x. To do that I either need the IPs of Steam content servers or, at the very least, what exact traffic srcds has, besides the game traffic.
I also need to make sure that the srcds never appear anywhere with the a.b.c.x IP, only with the a.b.d.x IP.