Date: Sun, 04 Feb 2018 21:01:34 +0000 From: bugzilla-noreply@freebsd.org To: freebsd-bugs@FreeBSD.org Subject: [Bug 225668] 'su' command reads /etc/hosts and calls name resolution erroneously Message-ID: <bug-225668-8@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=225668 Bug ID: 225668 Summary: 'su' command reads /etc/hosts and calls name resolution erroneously Product: Base System Version: 11.1-RELEASE Hardware: amd64 OS: Any Status: New Severity: Affects Many People Priority: --- Component: bin Assignee: freebsd-bugs@FreeBSD.org Reporter: feh@fehcom.de Created attachment 190321 --> https://bugs.freebsd.org/bugzilla/attachment.cgi?id=190321&action=edit My /etc/hosts file + /etc/resolv.conf + capture of the name lookup following the 'su' command Hi, upon calling 'su', su does the following: - it reads /etc/hosts, - it misinterprets an entry here with a colon as token in the first column, - it uses a DNS stub resolver to forward this crippled name for unqualified name resolution. Given this behaviour, 'su' leaks information via DNS. After forwarding the information to a DNS cache server, the initial call of 'su' waits for a time-out (about 500 msec). Usually, the cache server returns NXDOMAIN following his cache, 'su' seems to work faster the following calls. Attached you will find a documentation of this behaviour. Regards. --eh. -- You are receiving this mail because: You are the assignee for the bug.
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