On Mon 18 Sep 2017 at 23:47:18 +0300, Reco wrote: > On Mon, Sep 18, 2017 at 07:48:53PM +0100, Brian wrote: > > On Mon 18 Sep 2017 at 20:13:44 +0200, deloptes wrote: > > > > > Reco wrote: > > > > > > > The question is - since 'localhost.localdomain' is special, what happens > > > > if such hostname is chosen during the installation? > > > > > > well, now we all know what happens :) > > > > True, we know the OP has a problem with with sudo. > > That's what lie on surface. Any software that implements > uname/gethostbyname sequence would exhibit similar behavior. > > > > What we do not know > > is the hostname he chose during the installation, although it looks like > > it was "localhost" from the second line of > > > > 127.0.0.1 localhost > > > > 127.0.1.1 localhost > > I agree. > > > The installer recommends a single word for the hostname. The "single" > > aspect is the result of a number of years of experience and bug reports. > > And let's not forget RFC 952 (obsoleted by RFC 1123), which states: > > A "name" (Net, Host, Gateway, or Domain name) is a text string up to 24 > characters drawn from the alphabet (A-Z), digits (0-9), minus sign (-), > and period (.). Note that periods are only allowed when they serve to > delimit components of "domain style names". > > RFC 1123 lifts some restrictions: > > One aspect of host name syntax is hereby changed: the restriction on the > first character is relaxed to allow either a letter or a digit. Host > software MUST support this more liberal syntax. > > Host software MUST handle host names of up to 63 characters and SHOULD > handle host names of up to 255 characters. > > But does not says anything about dots, so restrictions of RFC 952 still > apply. > > > Although "localhost.localdomain" is not an invalid hostname > > I agree as long as 'invalid' is defined as 'kernel does not accept it'. > For instance, one can set nodename as 'localhost.local' and watch avahi > explode. Or, say, '_localhost', if one intends to wreak havoc in local > DNS's SRV records. > The kernel is surprisingly liberal at these things. > > > the OP does not appear to have used it. (We have not been given the > > contents of his /etc/hostname explicitly). > > True. We also did not see the contents of sysctl.conf (and those *other* > files that can store kernel tunables), custom init.d scripts and custom > systemd units if there were any. > > To make things more confusing, 'localhost.localdomain' could be a > 'transient' hostname, not a 'static' one (aka /etc/hostname). > > It's one of those things I prefer to debug with auditd on. Too many > possibilities otherwise. > > > What was the problem with his resolv.conf? Have I missed that? > > OP used an unspecified VPN client which put an additional entry into > /etc/resolv.conf on start, but failed to clean it up on stop.
Much clearer now. Your attention to explaining in detail is appreciated. -- Brian.