Packet generators - are these possible?

[rcgldr]

I know that there are packet sniffers, but I'm wondering if a computer is not behind a router (such as cable modem or dsl with external ip setups (usually for multiple external ip's, one for each computer), if a program made to generate and output packets could directly generate a packet with a false ip (maybe the ISP would prevent this). In one of the games I play, there was a recent one time incident where somehow players were being affected in a strange non game like behaviour, and since the game hasn't been updated in over a year, it seems unlikely that this would be a game bug, so my next guess is somehow packets between players were somehow getting deliberately corrupted. There may be other explanations, such as packets without a fake ip creating some sort of false collision detection on the other players games to create the bizarre reactions I saw (I wasn't affected, just witnessed the effects on two other players).

I'm not trying to create such a thing, I only want to know if it's possible without explaining how it could be done (I don't want to contribute to the creation of a game hack).

 

[jedishrfu]

Yes, I've heard of hacks where a network stream is intercepted and packets are injected into the mix that look similar to the other traffic but may not the correct hash codes.

In one case brought up by my instructor of communications, he told us of an example where crooks had intercepted an interbank network and slowly injected badly coded money transfers. The idea was to flood the bank with transfers that had to be reviewed in the hopes that the reviewer would eventually conclude there's something wrong with stream today and that the bad transfers are actually okay to approve.

Here's something on packet injections:

http://en.m.wikipedia.org/wiki/Packet_injection

 

[B0b-A]

... program made to generate and output packets could directly generate a packet with a false ip ...

That sounds like a description of "IP address spoofing" ... http://en.wikipedia.org/wiki/IP_address_spoofing

 

[rcgldr]

My question was about a potential type of hack against a particular game, where the goal could be just interfering with game play and making it appear that the source of the interference was from another source via the spoofed ip. Reading the wiki article, it appears that it is possible and some cases has a legitimate use, such as testing a server (although some or most of this testing could be done on a local network versus the internet).