I am trying to join my friend's Garry's Mod server and Steam is telling me that Garry's Mod is trying to launch with optional parameters. I don't know why, and he is telling me that he does not know.

The code it is trying to run is:

+connect p2p:(a long string of numbers is here).

What does this mean exactly? Should I be concerned? As of now, I have not connected yet.

Update: I tried to join a friend's Borderlands 2 game and it gave me a similar thing.

It tried to run:

+connect_lobby (a long string of numbers)

Is Steam just displaying something it normally doesn't?

Update: It has stopped loading them up with optional parameters, or at least showing me that it has been.

  • Does this only appear after you click on a friend's invite to join a server or you click to join a friend? I havea a feeling it's steam's mechanism of telling the game which server to join upon launching the game
    – Draken
    Aug 31, 2017 at 8:28
  • @Draken in the GMOD instance I tried to join through the PM tab I had with them, while on the BL2 instance I tried to accept an invite that they sent me.
    – The Man
    Aug 31, 2017 at 18:44

2 Answers 2


Perfectly normal.

The game has to know somehow that you intend to join your friend. Thats what the parameters are for, those allow you to be connect to the same multi-player session.

  • 1
    It's not normal such a message should appear though, normally that message should be hidden and not visible to the user. I'm curoious on why they are now being warned about this
    – Draken
    Aug 31, 2017 at 9:05
  • 1
    @Draken i cant check since i am at work but i believe there is an option in the Settings froM Steam to notify about that. Maybe they added this also as an security feature.
    – Shaeldon
    Aug 31, 2017 at 9:37

Looking at the SteamAPI documentation, this does appear to be normal:

If the user outside a game chooses to join, your game will be launched with the parameter +connect_lobby <64-bit lobby id>, or with the callback GameLobbyJoinRequested_t if they're already in-game.

I can't find anything in the documentation for +connect p2p, but I'm sure its something along the same lines as the other optional parameter you've seen.

  • But why is steam warning that it's launching with these optional parameters? I've joined many a friend's game on Steam via invite and following them through their profile and never been warned. It's odd that steam is warning this. Is this a new update, has the OP turned a flag on by accident?
    – Draken
    Sep 7, 2017 at 13:32
  • Note: These are parameters being passed to the game executable, so they don't have to be the same for every game.
    – Powerlord
    Sep 7, 2017 at 20:14

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