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Re: [Samba] getent not working after installing firewall (SOLVED)




On Tue, 5 Mar 2019 08:39:23 +0100 Peter Milesson wrote:
>
> On 05.03.2019 7:14, Mark Foley via samba wrote:
> > On Tue, 5 Mar 2019 06:17:59 +0100 Reindl Harald <h.reindl@xxxxxxxxxxxxx> wrote:
> >> Am 05.03.19 um 00:22 schrieb Mark Foley via samba:
> >>> /etc/resolv.conf:
> >>> nameserver 192.168.0.2
> >>> nameserver 209.18.47.62
> >>>
> >>> /etc/hosts:
> >>> 127.0.0.1               localhost
> >>> 192.168.0.60            ccarter
> >>>
> >>> So, the gateway is the Sonicwall firewall, 192.168.0.1. Nameservers are the DC (192.168.0.2)
> >>> and one of the ISP name servers. The IP is static and is set in /etc/hosts. At this point,
> >>> there should be no issues or questions with respect to which gateway or DHCP usage (DHCP is not
> >>> being used)
> >> besides that oyu really could strip your quotes why in the world are you
> >> doing that? there is no point except asking for troubles when you mix
> >> your DC and a external nameserver
> > Personally, I like the quotes. It gives me, and hopefully other, a clearer picture of the
> > problem and what has been tried. A reader can always skip to the bottom.
> >
> > ANYWAY, Standby! I may have the problem solved. I need to do a bit more experimentation with a
> > couple of components, but I think it might be fixed. I'll post again later when I've confirmed.
> >
> > --Mark
> >
> Hi folks,
>
> I'll poke a stick into this, due to recent experiences.
>
> Essentially, it's not a Samba problem. It's a network problem. First, 
> make sure your devices and configurations are in order. Then it may, or 
> may not work anyway.
>
> For different reasons, I had to make a slight network topology change. I 
> removed the previous gateway/router, and is now using a Cisco ASA as 
> firewall/router. The Cisco people are very explicit in stating that the 
> ASA is a firewall, not a router. It's possible to configure and use it 
> as a router anyway (though you need a PhD in Cisco ASA configuration). 
> The Cisco ASA was given the previous gateway IP.
>
> Behind the firewall router are 7 different subnets/VLANs. In the main 
> LAN are a bunch of Windows servers in a AD domain. One of the VLANs 
> contains a Samba ADDC, a Samba fileserver, and Windows clients. The 
> Samba domain machines may connect to the Windows domain, but not the 
> other way around. The Windows VLAN, and the Samba VLAN have got internet 
> access. The main DNS servers are in the Windows AD DC, and the backup 
> Windows AD DC. There is one single time source for the main LAN and VLANs.
>
> After making the changes, I made a very thorough check that everything 
> is working. After 4 days I get a call, that 2 clients in the Samba 
> domain cannot contact the mail server, which is in the Windows domain. 
> Also, those 2 clients cannot connect to a specific printer in the 
> Windows domain. Also, the printer seems to be jibbering, transmitting 
> garbage about 10 times/sec. All other clients in the Samba domain can 
> connect to the mail server without any problems. Testing, retesting, 
> checking firewall rules, checking DNS responses, restarting computers, 
> again, again, again. Everything is OK. But still it does not work.
>
> Comes after hours, then I make a complete, total reset of all network 
> devices, all servers, and turning off client computers. It's a small 
> network, so it was manageable during a long evening. After that, 
> everything working flawlessly. Even the printer stopped jibbering.
>
> My only conclusion here is that something very stale was still cached 
> somewhere. I'm exclusively using HP equipment for switching, so there's 
> no no-name, undocumented cheapo stuff in the network. But nobody is 
> perfect...
>
> Hope that my experiences can give you some input and help.
>
> Best regards,
>
> Peter

Peter - yes! That's exactly why I said "Standby" in my previous message.  It turns out that my
testing by setting a single workstation to the correct gateway (192.168.0.1) was insufficient. 
I found the place to change the setting in dhcpd.conf: "routers = 192.168.0.1", then I
restarted dhcpd on the DHCP server (AD/DC), and then reset the network cards, or rebooted
several of the workstations.  The workstations did get the correct gateway, but then I could
connect to nothing! Not even the NAS which requires AD authentication. 

So, I cleared caches on the DC and rebooted EVERYTHING: AD/DC, all workstations.  When things
came back up, everything was working!!! Similar to your experience.  I've been working on this
for three days. 

First of all, everyone who's been telling me that it had something to do with the gateway
setting was correct. Apparently this setting is entangled in lots of other things and simply
having the AD/DC's gateway and a domain member's gateway set correctly is not enough. Rebooting
everything, with the correct gateway configured in dhcpd.conf, propigates the correct settings
throughout.

Thanks all for your patience and feedback.

With respect to the continued thread about firewalls and devices, I quite agree with the
critiques about their expense and complexity.  I have been doing just fine for years using
iptables in my Internet-facing servers.  I've tried Sonicwall in the past, found it a pain to
configure, and returned it.  I just got off the phone with the Sonicwall tech who helped me
through the labyrinthine process of simply port-forwarding.  But, orders are orders!

--Mark

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