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[Solved]DHCP Client not getting DNS Server

Hey Guys!

So I have my Sophos GW configured to be a DHCP server. The DHCP Client is getting an IP address and getting the proper gateway, but it isn't getting the DNS server. When I try to run any kind of nslookup, it fails because there are no DNS servers configured. When I run nslookup and point it to my Sophos GW, it resolves instantly. So the DNS is working fine, but the DHCP Client is not getting it...

In the DHCP setting I have DNS Server 1 pointing to the internal IP (same IP i used for nslookup). No DNS 2. GW is the same internal IP (and this works).

Any ideas on what to check next?

Thanks!
-jon

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0 BarryG over 10 years ago

Hi & Welcome,

1. what OS is on the client?

2. UTM version #?

Barry
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0 jdmoore0883 over 10 years ago in reply to BarryG

Thanks for the response.

1. what OS is on the client?

A - I have tested with a few clients. Various Linux distros mostly, but also Windows 8

2. UTM version #?

A - It is newer... 9.3.something
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0 BarryG over 10 years ago

And you've run 'ipconfig /all' on windows and confirmed no DHCP server is set?
Sounds like something may be set wrong in the DHCP settings on the UTM; can you post a screenshot? Maybe a typo error.

Barry
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0 justmy2centx_01 over 10 years ago

can you try recreating the dhcp server and just leave everything to defaults?
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0 pumpkinpower over 10 years ago

I had this issue when the DHCP server was running on a vlan'd and aggregated trunked connection, client's simply wouldn't get an assignment, everything else was fine. Removing the link aggregation resolved my issue. My UTM 9 now works fine with 4 dhcp servers, one on each vlan on single port trunk to the switch.
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0 BAlfson over 10 years ago

Jon, do you have "Internal (Network)" in 'Allowed networks' in 'Network Services >> DNS'? Also, you might want to inspire your configuration from DNS Best Practice.

Cheers - Bob

Sophos UTM Community Moderator
Sophos Certified Architect - UTM
Sophos Certified Engineer - XG
Gold Solution Partner since 2005

MediaSoft, Inc. USA
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0 teched_01 over 10 years ago
What to packet captures on the UTM and client device show for as the content of the DHCP dialogue?

Does /var/chroot-dhcps/etc/dhcpd.conf look correct?

An example command (change interface as needed) for tcpdump on the UTM:
tcpdump -i eth1 -vv -X -n -s 65535 port 67 or port 68
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0 jdmoore0883 over 10 years ago in reply to BAlfson

Jon, do you have "Internal (Network)" in 'Allowed networks' in 'Network Services >> DNS'? Also, you might want to inspire your configuration from DNS Best Practice.

Cheers - Bob

So I went through all the above mentioned suggestions. An thank you everyone for the suggestions too BTW...

In the end though, it was something about he DNS Best Practrice that had ultimately resolved the issue.

In the best practices, someone mentions making sure that "'Use forwarders assigned by ISP' is not checked." I had mine checked. So after manually defining some OpenNIC - OpenNIC Project DNS Server, it is all working great now.

So weird that the forwarders assigned by the ISP does not work... But whatever, it's all working now.

Thanks for all the help!

EDIT: How do I mark this thread as solved?
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[Solved]DHCP Client not getting DNS Server

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