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Since minecraft.net is down or at least badly reachable, is it possible to play multiplayer offline? I know I can log in as one "Player" with the server setting online-mode=false, but the second offline player connecting kicks the first one because of the identical name.

Can this be circumvented?

(As Tyr comments, renaming the first connected player (or the second before connecting) would probably do the trick.)

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  • I came in fully expecting to downvote this question because it sounded like sheer nonsense from the title. +1 instead. Commented Jan 20, 2011 at 20:25
  • 1
    It seems like online-mode=false would get what you want, if you could just set your name in offline mode. I think there is a way, but I don't remember it right now. Commented Jan 21, 2011 at 5:13
  • @Tyr yeah that's the setting that allows one player to connect, if you remember how to change the offline name please remember to post it as an answer here...
    – Zommuter
    Commented Jan 21, 2011 at 5:59
  • What's the difference between doing this and being able to run an unauthorized copy? I.e., perhaps the reason this is difficult is because it is an anti-piracy feature?
    – Tim Holt
    Commented Feb 25, 2011 at 6:17
  • 2
    I wonder if there is a way someone could put a transparent proxy in place that caches the response.
    – Zoredache
    Commented Feb 26, 2011 at 23:10

4 Answers 4

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+50

The way to do this, is to have a server. Have the server set "online-mode" in it's server.properties file to false. Then start the minecraft client without authenticating it.

You can do that via typing this into "run" on Windows:

java -Xms512m -Xmx1024m -cp "%APPDATA%\.minecraft\bin\*" -Djava.library.path="%APPDATA%\.minecraft\bin\natives" net.minecraft.client.Minecraft "yournamegoeshere"

Or on an Apple Mac, open "Terminal" and enter:

java -Xms512m -Xmx1024m -cp "$HOME/Library/Application Support/minecraft/bin/*" -Djava.library.path="$HOME/Library/Application Support/minecraft/bin/natives" net.minecraft.client.Minecraft "yournamegoeshere"

The only downside of this is that anyone can log in with any name. But the upside is you do not need any third party programs, many of which are illegal.

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  • Does this still work?
    – Ape-inago
    Commented Mar 23, 2011 at 10:16
  • @Ape-inago I used it a couple of days ago, and seeing as how there hasn't been any new minecraft updates, I assume it should still work.
    – davr
    Commented Mar 24, 2011 at 21:44
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    I fixed it... there was an another .jar there that it was trying to load from when I was trying to mod the client. My bad.
    – Ape-inago
    Commented Mar 24, 2011 at 22:43
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    An oddity when running it this way: the main screen shows a quit button?
    – Ape-inago
    Commented Mar 24, 2011 at 22:54
  • @Ape-inago: running "java -Xmx1024M -Xms512M -cp ~/.minecraft/minecraft.jar net.minecraft.LauncherFrame" also shows the quit button.
    – WhyNotHugo
    Commented Jan 19, 2012 at 6:34
6

A strategy we have used before is to build your own authentication server (the protocol is available) and run that when minecraft.net is down.

You do ofcourse need to have a dabatase with usernames/passwords for this to work, and you would have to place a record in the hosts file whitch will point minecraft.net to the new authentication server.

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  • 1
    good idea, I didn't know the protocol was available. But isn't this already kind of gray?
    – Zommuter
    Commented Jan 26, 2011 at 13:19
  • The way we implemented it, only people who already had an account on minecraft.net, could log in. (We had an ingame verification system which would verify your account to the website account, which was used for the authentication server).
    – Ikke
    Commented Jan 26, 2011 at 13:32
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    Is this server available somewhere? I too would like to be able to play on my personal SMP server when minecraft.net goes down (as happens often)
    – davr
    Commented Feb 23, 2011 at 3:59
  • @davr No, it's not available, so you would have to build something yourself (or let it be build for you)
    – Ikke
    Commented Feb 23, 2011 at 7:47
  • Where is the protocol documented? Minecraft.net or the wiki don't seem to show any documentation on this.
    – WhyNotHugo
    Commented Jan 19, 2012 at 6:36
4

This used to be possible by placing both online-mode=false and verify-names=false... but it seems with recent updated the verify-names parameter was removed, and all players now come in as 'player'

In the past it would still let you connected to smp with these options and you would have your name as your regular minecraft name. The only way to do this now is to have a minecraft client that is downgraded to an older version and not letting it patch for these times.

If there are only two of you only 1 person would need the downgraded client, however I am not sure of the legality of downgrading his code using the methods easily found online so im going to not provide any links on how to do so.

EDIT: Some extra info verify-names command when it was in the game, checked your minecraft name against the authentication servers to make sure noone else was trying to use your name at the same time and that it was a valid account even after logging in.

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  • 2
    I'm afraid a downgraded client would also result in being unable to connect to the up-to-date server. Plus I don't have an older one and don't want to enter some gray zone there...
    – Zommuter
    Commented Jan 21, 2011 at 8:00
  • yeah that actually would cause some issues with server versions I suppose, I had previously not considered that. But yeah it starts to get a little strange if your not really familiar with the specifics. There was some talk of this feature comming back, or being modded in. With the popular server mod hey0 being closed, there may be some hope of this in the new wrapper, bukkit, but it would involve modding the server and waiting for the mod to be developed if it ever is.
    – Ward
    Commented Jan 21, 2011 at 8:03
-3

I'll put it simply: you can't play multiplayer offline.

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  • 5
    you can - just that the server must set online-mode to false
    – user8949
    Commented Jul 6, 2011 at 5:33
  • maybe I didn't phrase my question well, offline-multiplayer doesn't make much sense in general, what I meant was multiplayer while the minecraft server is down
    – Zommuter
    Commented Jul 6, 2011 at 9:59
  • Sure you can, you can have several minecraft copies on the same PC as the server.
    – WhyNotHugo
    Commented Jan 19, 2012 at 6:35

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