For years we ran a 'channel extender' product call RDS. It worked by front-endng FLIH for I/O interrupts to determine whether the I/O was to or from a supported device as defined to RDS. If not, the I/O was passed along for normal processing. If so, RDS redirected the I/O to its own network device for transmission (out); or written to the intended device (in). It sounds kludgy, but it worked amazingly well. The vendor was very forthright about the internals. We had occasional hardware problems with RDS, but I never once saw an OS failure caused by this technique.
This sort of thing is best not done at home. . . JO.Skip Robinson SCE Infrastructure Technology Services Electric Dragon Team Paddler SHARE MVS Program Co-Manager 626-302-7535 Office 323-715-0595 Mobile [email protected] From: John Gilmore <[email protected]> To: [email protected] Date: 03/01/2012 01:56 PM Subject: Re: Program FLIH backdoor - This is a criminal breach of security! Sent by: IBM Mainframe Discussion List <[email protected]> I don't want to put words in EJ's mouth; but if 'an exposure' were replaced by what I should call 'misuse' what he said is correct and not even controversial. I think there is an exposure, in the sense that this device lends itself very readily to abuse. I have seen no evidence that it has actually been misused in any but the tenuous sense that it adds clandestine overhead to the processing of every interrupt. The device itself has been much misused elsewhere. A number of viruses have, for example, used a Windows scheduled task---PC Health Data Collection is a favorite---to hijack PCs. Moreover, now that its use has been publicized here, the scheme it embodies---not, a fortiori, the offender's code itself---is all but certain to be used irresponsibly by others; even though, as I believe, the the offender's code itself commits no substantive offense it it is, I think, guilty of the admittedly much subtler offense of providing a template for others, who are bent on mischief, to use. John Gilmore, Ashland, MA 01721 - USA ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
