I just upgraded from Linux Mint 14 to 17.2 and Thunderbird 38.4.0 is having problems. It can't resolve any host names except those in
/etc/hosts. Everything else I've tried, including Firefox, the host command, ping, etc. works fine.
If I add my mail server host name to
/etc/hosts, it works. Without it, it fails to connect. It also can't connect to the Mozilla sites such as the add-ons site.
I created a new user, logged in as that user, and tried to set up Thunderbird. It failed in the same way, unable to resolve host names.
I tried disabling ipv6 in the Thunderbird config editor but that made no difference.
Proxy settings are set for no proxy.
/etc/resolv.conf is correct.
hosts: files mdns4_minimal [NOTFOUND=RETURN] dns
Changing it to just
files dns makes no difference.
strace shows that Thunderbird is reading
/etc/resolv.conf and sending DNS queries.
tcpdump shows the DNS queries and results. But, there are no attempts to connect to the mail server hosts.
This appears to be a network configuration problem. I tried to move over my network setup from Linux Mint 14 but appears enough has changed that it doesn't work anymore. If I remove the static network configuration from
/etc/network/interfaces and just let it use DHCP, everything works.
Here's what I added to
iface eth0 inet static address 192.168.0.4 netmask 255.255.255.0 gateway 192.168.0.1 dns-nameservers 192.168.0.1 192.168.1.254 22.214.171.124 auto eth0
When that's removed (and the system rebooted),
/etc/resolv.conf shows just a single DNS server at 127.0.1.1, which appears to be some built-in DNS server. I don't know how that makes a difference, but it does.
What's the correct way to configure Linux Mint for a static IP address?