[Users] strange problem with nagios nrpe server

[Kirill Korotaev]

BTW,

Do you use/have WINS server? it is usually used for names resolution
and can be used w/o broadcasts, so it should work even with your current
configuration.

http://www.oreilly.com/catalog/samba/chapter/book/ch07_03.html

Thanks,
Kirill


Kirill Korotaev wrote:
> Steve Wray wrote:
> 
>>Just one other possible data point.
>>
>>I may have just dismissed these problems as some kind of creeping 
>>senility but I've seen some other bizarre issues with VMs migrated into 
>>OpenVZ.
>>
>>One of these is to do with Samba filesharing.
>>
>>When the VM is migrated into OpenVZ from Xen, samba fileshares on the VM 
>>can be accessed from Windows *only* by FQDN not by bare hostname.
>>
>>Note that this broke *existing* mapped network drives for Windows users.
>>
>>Also note that this did *not* affect Linux nor OSX clients; only Windows.
>>
>>Since I've verified that this wierdness is *only* apparent when the VM 
>>was running under OpenVZ not under Xen I'm not inclined to believe that 
>>I am going insane when I find that NRPE under Debian Sarge has a problem 
>>when running under OpenVZ and not under Xen.
>>
>>
>>It starts to seem that OpenVZ can produce all *kinds* of unpredictable 
>>behavior... either that or I really am going mad complete with 
>>hallucinations :-/ Not discounting that possibility out of hand...
> 
> 
> Oh, don't say so. Everything should have a logical explanation.
> And I guess I know the answer to this one.
> 
> First of all, plz check that you don't have any kind of firewall
> rules in host system and VE with 'iptables -L'.
> 
> But the real suspect is broadcast network messages from NetBIOS protocol.
> Working FQDN means that host can be found via DNS and by IP.
> Non-working short hostnames mean that your hosts are not setup
> in default domain in DNS and that name resolution via netbios failed.
> 
> You need to connect your VE to ethX adapter using veth (virtual ethernet)
> adapter and Linux bridge. This will allow use of network broadcasts.
> The default venet networking is a secure IP-level networking which filters
> out broadcasts.
> 
> http://wiki.openvz.org/Virtual_Ethernet_device
> http://wiki.openvz.org/Differences_between_venet_and_veth
> http://forum.openvz.org/index.php?t=msg&goto=7295&&srch=samba#msg_7295
> http://en.wikipedia.org/wiki/NetBIOS
> 
> Forseeing your question about why venet is used as default networking type:
> 1. venet is more secure (see wiki).
> 2. venet is more scalable up to hundrends and thousands of VEs,
>    while veth/ethernet/bridge broadcasts/multicasts will simply kill (DoS) the node
>    in case of many VEs.
> 
> Thanks,
> Kirill
> 
>