Rkhunter And Prelink

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Can’t remember if I posted this before… We’re getting warnings from rkhunterWarning: Checking for prerequisites [ Warning ]
All file hash checks will be skipped because:
This system uses prelinking, but the hash function command does not look like SHA1 or MD5.

Now, googling, I find people saying to rm /etc/prelink.cache, then run rkhunter –propupd.

Works. And then, prelink runs in the middle of the night, via
/etc/cron.daily, and when the cron job of rkhunter runs, it’s back to complaining.

Anyone have any ideas what’s going on here? I don’t see anything in the prelink.conf, or any options in the prelink manpage to tell is what hash to use.

mark

6 thoughts on - Rkhunter And Prelink

  • Prelink is evil, in a sense of what it does. Allegedly it helps to load into memory binaries and libraries faster, for that it TOUCHES every one of them regularly. This effectively defeats the way we watch for system integrity by tracking all system files and libraries information, such as:
    file sizes, time stamps, inode numbers, checksums. The very moment RedHat made prelink installed by default, I was so upset that you can feel these my feelings in my writing now are still present. I got rid of prelink, and I rid of it specifically on my kickstart files. Two or three years down the road RedHat came to its senses and removed prelink from what is installed by default. I’m surprised, Mark, that you still have it some place. Any specific reason? If not, get rid of prelink which does waaay more harm than it does good IMHO.

    Valeri

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    Valeri Galtsev Sr System Administrator Department of Astronomy and Astrophysics Kavli Institute for Cosmological Physics University of Chicago Phone: 773-702-4247
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  • IMHO that means keeping the evil in the loop, the loop that should be tightest, slimmest and awfully trusted. Which partly much defeats the reasons why we watch the files. And it doesn’t help with ever changing file inode numbers, timestamps, only checksums (I use different from OP’s system integrity tools, so I’m not certain if the last matters for OP). Anyway, my decision was to get rid of evil. But that is me who puts system integrity three levels above how fast the system feels (and feeling is only about how fast the application starts, not how fast it runs). Sorry, my attitude to prelink will keep showing always ;-)

    Valeri

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    Valeri Galtsev Sr System Administrator Department of Astronomy and Astrophysics Kavli Institute for Cosmological Physics University of Chicago Phone: 773-702-4247
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  • Check in the rkhunter log file (probably /var/log/rkhunter.log). It will tell you what hash command it is using as it runs. For prelinking it must be SHA1 or MD5 (set via the HASH_CMD config option). If you set it to literally ‘SHA1’ or
    ‘MD5’, then RKH will look for the relevant command.

    John.

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