| Subject: | DHCP DNS issue |
| Date: | Mon, 19 Jun 2017 19:12:11 +0000 |
| To: | "dhcp-bugs@isc.org" <dhcp-bugs@isc.org> |
| From: | "Sören Busse" <soeren.2011@live.de> |
Hi,
we're using the isc-dhcp-server in our enviroment, but since the version 4.3 there is an issue with the domain lookup.
The problem is now that we get an "Can't contact LDAP server" error, altough the domains are pointing to 127.0.0.1.
So I've done a tcpdump which shows that the DHCP server tries to make requests to an external ip, which is the A-Record
of foss-cloud.org
02:11:05.373307 IP 192.168.5.101.46016 > 62.204.105.153.636: Flags [S], seq 3665195687, win 29200, options [mss 1460,sackOK,TS val 2152987841 ecr 0,nop,wscale 7], length
0
02:11:06.396480 IP 192.168.5.101.46016 > 62.204.105.153.636: Flags [S], seq 3665195687, win 29200, options [mss 1460,sackOK,TS val 2152988148 ecr 0,nop,wscale 7], length
0
02:11:08.529804 IP 192.168.5.101.46016 > 62.204.105.153.636: Flags [S], seq 3665195687, win 29200, options [mss 1460,sackOK,TS val 2152988788 ecr 0,nop,wscale 7], length
0
02:11:12.583127 IP 192.168.5.101.46016 > 62.204.105.153.636: Flags [S], seq 3665195687, win 29200, options [mss 1460,sackOK,TS val 2152990004 ecr 0,nop,wscale 7], length
0
02:11:20.689774 IP 192.168.5.101.46016 > 62.204.105.153.636: Flags [S], seq 3665195687, win 29200, options [mss 1460,sackOK,TS val 2152992436 ecr 0,nop,wscale 7], length
0
If I now try a domain which points to
127.0.0.1 for example localtest.me, the DHCP server connects without any issues.
The same issue appears also if there is no internet connection, so no DNS request could be done altough there is a rewrite written in /etc/hosts which points to localhost/127.0.0.1.
For more information here is also a thread on the gentoo forum, where I've put some more details:
Kernel: Linux localhost 4.10.1-gentoo
Gentoo version 2.2.
This seems to be a very important bug that should be resolved.
If you need further information don't hesitate to contact me.
Kind regards
Sören Busse