NIS and NIS+ ephemeral ports

From: Dylan Loomis (dylanat_private)
Date: Wed Jan 13 1999 - 11:59:56 PST

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    Aleph, feel free to edit the first part out but I didn't find it in the
    BUGTRAQ archives so just tacked it in.
    
    Prelude: first got a brand new Ultra10 from sun, and surprsingly it had
    two root partitions.  So booted from the second root, and found, in addition to
    the system accts, an account: sfa (sun field admin???) ran crack against it and
    the password ended up being: 'debug' no single quotes.  This was a brand new,
    Solaris 2.6 box.
    
    Question: at one of the sites I work at, we run NIS and NIS+ and I found that
    even though NIS and NIS+ servers use a high ephemeral port, upon reboot this
    port didn't change in some of the machines.
    
    In effect this means that I can write scripts to connect directly to the port
    and by-pass the portmapper.  Why is this bad?  Well because a lot of sites
    just block 111 (portmapper) and leave the rest open (ftp other stuff might
    need them).  In addition, since it doesn't run from inetd, I am pretty sure
    you can't run tcpwrappers.  Since it bypasses the portmapper, a secure
    portmapper isn't much good either.  So if I can guess the high port, I can,
    in the case of NIS, get the hashed passwds quite easily.
    
    Workarounds include checking what ephem port your server runs, and blocking it
    at the firewall.  Just cutting off your NIS/NIS+ server from the outside world.
    
    What I want to find out: is this ephermeral port selection related to OS
    release?  To this end I am asking the BUGTRAQ readership to answer the
    following informal poll, I will organize the results and post a summary.
    Obviously I don't want your actual IP or location, but would like:
    
    OS Release:
    Hardware:
    NIS or NIS+:
    same ports on reboot?:
    Patch level: <current | some_patches | patches_are_for_wimps>
    Ephem port for: ypserv, ypbind, yppasswd, nisd, nispasswd
    
    uname -a, rpcinfo -p server, should give you all the info above.  Below is
    data for machines I have already checked.  But, conflicting or supporting
    date is appreciated.
    
                                                    thx -DAL-
    
    -----------------------
    
    OS Release: SunOS 5.5.1
    Hardware: sparc10
    NIS or NIS+: NIS+
    same ports on reboot?: yes
    Patch level: no patches (there is a reason for this! I swear)
    Ephem port for: ypserv, ypbind, yppasswd, nisd, nispasswd                           100300    3   udp  32772  nisd
        100300    3   tcp  32771  nisd
        100303    1   tcp  32777  nispasswd
    
    OS Release: SunOS 5.6
    Hardware: sparc20
    NIS or NIS+: NIS
    same ports on reboot?: <1024 changed, ephem ports same
    Patch level: some patches
    Ephem port for: ypserv, ypbind, yppasswd, nisd, nispasswd
        100004    2   udp    772  ypserv
        100004    1   udp    772  ypserv
        100004    1   tcp    773  ypserv
        100004    2   tcp  32772  ypserv
        100007    3   udp  32776  ypbind
        100007    2   udp  32776  ypbind
        100007    1   udp  32776  ypbind
        100007    3   tcp  32774  ypbind
        100007    2   tcp  32774  ypbind
        100009    1   udp    788  yppasswdd
        100007    1   tcp  32774  ypbind
    
    OS Release: SunOS 5.6
    Hardware: Ultra1
    NIS or NIS+: NIS+
    same ports on reboot?: unknown awaiting result
    Patch level: current
    Ephem port for: ypserv, ypbind, yppasswd, nisd, nispasswd
        100300    3   udp  35160  nisd
        100300    3   tcp  37795  nisd
        100303    1   tcp  37801  nispasswd
    
    --
    -DAL-
    dylanat_private
    



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