Enforcing No Shared IDs
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Video Transcription
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>> Hey there, Cybrarians.
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Welcome back to the Linux+ course here at the Cybrary.
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I'm your instructor Rob Goelz.
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In today's lesson, we're going to be
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discussing enforcing no shared IDs.
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Upon completion of today's lesson,
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you're going to be able to understand
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the importance of ensuring that we
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don't have user or group ID shared on our systems.
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We're going to explain where we can look to
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see if shared IDs can be found.
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In Linux, every user and group have to have a unique ID.
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We know from experience
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now and going through the course that are
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user IDs are a UID and group ID is a GID, UID or GID.
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If two users or groups share the same ID,
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then there's really no way to account
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for the actions that might be taken.
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Users could have access to another user's files,
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or a group might have access to
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a different groups files or resources because it
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all looks in the Linux system as if it's
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the same user or same group.
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Additionally, we may have auditing policies in
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place that are tied to the UID or GID.
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If we have shared UIDs or shared GIDs it
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effectively is breaking our security measures
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that we've put in place.
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We can find shared IDs by
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looking at some of
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the files that we've already discussed.
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In Module 8, we discussed users and groups,
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and we talked about file locations in that module.
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To find duplicate user IDs,
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we can search in the etc password file.
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If we look in etc password,
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the third column contains the user ID or the UID.
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We can see on the right-hand side,
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the upper image there,
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we see test x 1,002,
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1,002 that third column
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is the user ID for that test user.
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If we're looking for duplicate group IDs,
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we can searching the etc group for a file.
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In etc group we're looking at column three as well.
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What we're looking for there,
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we can see that on the bottom image.
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Adm X 4, the number four,
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that's the group ID for
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the adm group and so on and so forth,
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4, 5, 6, 7, 8,
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9, 10, and 12.
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With that, in this lesson,
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we covered the importance
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>> of ensuring IDs are not shared.
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>> Then we talked about where to find shared IDs,
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looking at etc password for
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UIDs and etc group for group IDs.
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Thanks so much for being here and I look
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forward to seeing you in the next lesson.
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