Re: Servers just doen't work (after following the troubleshooting page)

In article <dhd2md$lkg$1@xxxxxxxxxxxxxxxxxx> "David Schwartz"
<davids@xxxxxxxxxxxxx> writes:
>
>"S P Arif Sahari Wibowo" <arifsaha@xxxxxxxxx> wrote in message
>news:Pine.LNX.4.62.0509272114330.26206@xxxxxxxxxxxxxxxxxxxxxxxx
>
>> Note to self: udp communications may not work with secondary IP / IP
>> aliases, specifically ntp won't work.
>
> Normally it will work just fine, it's just that NTPD has a bug that I've
>been complaining about for, well, a very long time (since at least September
>of 2001). A workaround is to pass ntpd the '-L' flag.

Hm, I assume that the bug you're referring to is the same as Danny
mentioned, that ntpd may/will respond with the wrong source address for
queries received on the wildcard socket (and actually I just now
verified that an old version of ntpd has that bug).

However the general theory of operation is that ntpd should bind a
socket to each individual address it is "supposed" to answer queries on
- then it can infer the destination address of the query (which isn't
available through the standard socket interface) based on which socket
the query is received on. I.e. if the address in question *is* bound to
a socket, the bug will not occur - and the OP claimed that ntpd *did*
have all the IP addresses bound (but I suspect he may be mistaken).

As to the -L flag, that's another of those unfortunate parameters that
have different meaning in different versions of ntpd - the official docs
say:

-L
Do not listen to virtual IPs. The default is to listen.

- i.e. just the opposite of what the OP needs. However I know for a fact
that at least some versions shipped with RedHat (including the one the
OP is using) have a -L option that does mean the opposite of the above,
i.e. it is required for correct operation with secondary/virtual/alias
addresses. In short, your advice is probably right for the OP, but not
universal.:-) I don't know whether this difference is due to changes in
the reference implementation or to special mods in the RedHat version.

--Per Hedeland
per@xxxxxxxxxxxx
.

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