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[20100605] Hiding other users' processes
Thus it was asked on #NetBSD:
<batence> I wanna set the top command work only for users process, not
                for all system
<batence> in freebsd command is sysctl security.bsd.see_other_uids=0/1
<batence> but I dunno for netbsd
<batence> eg I don't want users see other uids
<batence> only which they owned
Looking at the output of "sysctl -a" didn'r show anything obvious, but recalling the topic and with some digging, there actually is a sysctl switch for that in NetBSD: security.models.bsd44.curtain=1

Here's an example top(1) output with the default setting (0). My username is "feyrer", note that besides my processes, other users' processes are shown as well:

    load averages:  0.02,  0.01,  0.00;               up 11+15:08:30                           18:38:56
    24 processes: 23 sleeping, 1 on CPU
    CPU states:  0.0% user,  0.0% nice,  0.0% system,  0.0% interrupt,  100% idle
    Memory: 71M Act, 51M Inact, 552K Wired, 5560K Exec, 110M File, 27M Free
    Swap: 512M Total, 335M Used, 178M Free
    
      PID USERNAME PRI NICE   SIZE   RES STATE      TIME   WCPU    CPU COMMAND
        0 root     126    0     0K   16M pgdaemon   5:41  0.00%  0.00% [system]
      492 root      85    0  4792K  608K kqueue     0:06  0.00%  0.00% master
      113 root      85    0  2908K  860K select     0:05  0.00%  0.00% dhclient
      535 root      85    0  2900K  556K nanoslp    0:05  0.00%  0.00% cron
      155 root      85    0  2932K  548K kqueue     0:05  0.00%  0.00% syslogd
      496 postfix   85    0  4792K  888K kqueue     0:01  0.00%  0.00% qmgr
     4409 feyrer    43    0  2984K 1240K CPU        0:00  0.00%  0.00% top
     1197 root      85    0  8640K 3692K netio      0:00  0.00%  0.00% sshd
    24830 root      85    0  8640K 3692K netio      0:00  0.00%  0.00% sshd
     6949 feyrer    85    0  8640K 2828K select     0:00  0.00%  0.00% sshd
    28093 feyrer    85    0  8640K 2828K select     0:00  0.00%  0.00% sshd
    12391 feyrer    85    0  2132K 1876K pause      0:00  0.00%  0.00% tcsh
    25579 feyrer    85    0  2132K 1876K pause      0:00  0.00%  0.00% tcsh
     5773 postfix   85    0  4792K 1868K kqueue     0:00  0.00%  0.00% pickup
     1929 root      85    0  2128K 1828K ttyraw     0:00  0.00%  0.00% tcsh
    29212 root      85    0  2972K 1164K kqueue     0:00  0.00%  0.00% inetd
    25972 root      85    0  2824K 1076K pause      0:00  0.00%  0.00% ksh 
Likewise, I see a number of processes in ps(1):
% ps -aux | wc -l
      26
Now let's change the sysctl:
# sysctl -d security.models.bsd44.curtain
security.models.bsd44.curtain: Curtain information about objects to users not owning them.
# sysctl -w security.models.bsd44.curtain=1
security.models.bsd44.curtain: 0 -> 1
After this, the top(1) output looks like this:
    load averages:  0.02,  0.01,  0.00;               up 11+15:08:45                           18:39:11
    5 processes: 4 sleeping, 1 on CPU
    CPU states:  0.0% user,  0.0% nice,  0.2% system,  0.0% interrupt, 99.8% idle
    Memory: 71M Act, 51M Inact, 552K Wired, 5416K Exec, 110M File, 28M Free
    Swap: 512M Total, 335M Used, 178M Free
    
      PID USERNAME PRI NICE   SIZE   RES STATE      TIME   WCPU    CPU COMMAND
     4409 feyrer    43    0  2984K 1240K CPU        0:00  0.00%  0.00% top
    28093 feyrer    85    0  8640K 2828K select     0:00  0.00%  0.00% sshd
     6949 feyrer    85    0  8640K 2828K select     0:00  0.00%  0.00% sshd
    12391 feyrer    85    0  2132K 1876K pause      0:00  0.00%  0.00% tcsh
    25579 feyrer    85    0  2132K 1876K pause      0:00  0.00%  0.00% tcsh 
This reduced set of processes is also shown in ps(1):
% ps -aux | wc -l
       7
In other words, only my processes are displayed. (If you wonder about the difference between the 7 processes shown in top and the seven ps(1)-lines: the latter includes a heading).

Note that this "filtering" does not apply to the root user, i.e. he can still see all processes.

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Disclaimer: All opinion expressed here is purely my own. No responsibility is taken for anything.

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