disabling X connections from a remote systems

[Ramakrishnan M <rkrishnan@vayu.ee.iitm.ernet.in>]

I have a computer here,which is relatively slow one.Recently I noticed
that people from other labs are logging in and exporting display and using
netscape.I would like to disable this without using xhost - .What files
should I modify
TIA

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Ramakrishnan M
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