http://bugzilla.opensuse.org/show_bug.cgi?id=1180497 Bug ID: 1180497 Summary: In /etc/hosts Localhost declared valid both for IPV4 and IPV6 loop interfaces breaks some local servers Classification: openSUSE Product: openSUSE Tumbleweed Version: Current Hardware: x86-64 OS: openSUSE Tumbleweed Status: NEW Severity: Normal Priority: P5 - None Component: Network Assignee: screening-team-bugs@suse.de Reporter: gianlucap@gmail.com QA Contact: qa-bugs@suse.de Found By: --- Blocker: --- In the most recent tumbleweed release, running in a freshly installed Anaconda python environment the following command to start Jupyter Notebook, a local interactive server popular in data science applications, and accessible via web browser: :~> jupyter notebook returns an error 99 {unable to bind}. Upon contacting the developers I have been told to perform the following change in /ETC/HOSTS BEFORE 127.0.0.1 localhost # special IPv6 addresses ::1 localhost ipv6-localhost ipv6-loopback AFTER 127.0.0.1 localhost # special IPv6 addresses ::1 localhost6 ipv6-localhost ipv6-loopback The problem according to them is that localhost is both the IPV4 and the IPV6 adress, I was told that is not a good practice for IPV6 and IPV4 loop interface to be called both localhost, as it might break things. As this is a very basic part of the system, I assume you had a very good reason to do so, however I want to bring to your attention this incident. Thank you -- You are receiving this mail because: You are on the CC list for the bug.