Exploiting network services question

[just-a-nick () gmx net]

Hi everyone,

I have a question regarding the exploitation of network services.
If I send the following string to a service

["A"x78]["abcd"][junk - up to 430 bytes]

I can control eip with "abcd". How can I exploit this? Is there a good
tutorial that I should read? Unfortunately I did not find anything usefull
with google...

Thanks a lot for you help!
  Thomas

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