Public bug reported:
This is a re-report of
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/401202 since that
one was apparently closed as no-fix simply because it was too old.
This still occurs in xenial.
Original description:
Regardless of ndots option in /etc/resolv.conf, when NXDOMAIN is returned from
the DNS server then resolver always try another attempt with the original name
extended by what is in search option.
For example, if you're looking for very.long.url.nowhere and there is a line
"search ubuntu.com" in resolv.conf you will get addres of server
very.long.url.nowhere.ubuntu.com if such exists. It is incorrect, it should
occurs only for urls having less that ndots option dots in its name.
My system is a standard Ubuntu Xenial desktop amd64 using network
manager and the default configured Wired Connection 1 (i.e. DHCP).
To reproduce:
- sudo install /dev/fd/0 /etc/NetworkManager/dnsmasq.d/domain
<<<'log-queries=extra'
- sudo killall dnsmasq
- ping some.long.non-existent.name
- Watch /var/log/syslog
In my case:
Mar 20 23:19:22 eragon dnsmasq[27367]: 46 127.0.0.1/40646 query[A]
some.long.non-existent.name from 127.0.0.1
Mar 20 23:19:22 eragon dnsmasq[27367]: 46 127.0.0.1/40646 forwarded
some.long.non-existent.name to 192.168.5.1
Mar 20 23:19:22 eragon dnsmasq[27367]: 46 127.0.0.1/40646 reply
some.long.non-existent.name is NXDOMAIN
Mar 20 23:19:22 eragon dnsmasq[27367]: 47 127.0.0.1/52417 query[A]
some.long.non-existent.name.sebunger.dnsalias.org from 127.0.0.1
Mar 20 23:19:22 eragon dnsmasq[27367]: 47 127.0.0.1/52417 forwarded
some.long.non-existent.name.sebunger.dnsalias.org to 192.168.5.1
Mar 20 23:19:23 eragon dnsmasq[27367]: 47 127.0.0.1/52417 reply
some.long.non-existent.name.sebunger.dnsalias.org is <CNAME>
Mar 20 23:19:23 eragon dnsmasq[27367]: 47 127.0.0.1/52417 reply
sebunger.dnsalias.org is 203.173.156.30
My /etc/resolv.conf (which is a sym-link to ../run/resolvconf/resolv.conf
# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
# DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
nameserver 127.0.1.1
search sebunger.dnsalias.org
options ndots:1
(I added the options ndots with no effect)
** Affects: linux (Ubuntu)
Importance: Undecided
Status: Incomplete
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https://bugs.launchpad.net/bugs/1674273
Title:
Resolver ignores ndots option
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