Date: Fri, 14 Jul 1995 11:40:02 -0700 From: John Polstra <jdp@polstra.com> To: freebsd-bugs Subject: conf/620: Default /etc/hosts.equiv causes rsh/rlogin hangups Message-ID: <199507141840.LAA22368@freefall.cdrom.com> In-Reply-To: Your message of Fri, 14 Jul 1995 11:07:25 -0700 <199507141807.LAA07539@freebie.polstra.com>
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>Number: 620 >Category: conf >Synopsis: Default /etc/hosts.equiv causes rsh/rlogin hangups >Confidential: no >Severity: serious >Priority: high >Responsible: freebsd-bugs (FreeBSD bugs mailing list) >State: open >Class: sw-bug >Submitter-Id: current-users >Arrival-Date: Fri Jul 14 11:40:01 1995 >Originator: John Polstra >Organization: Polstra & Co., Inc. >Release: FreeBSD 2.0-BUILT-19950603 i386 >Environment: Stock 2.0.5-RELEASE installation >Description: The default version of "/etc/hosts.equiv" that is created during system installation is invalid. It contains "comments" which begin with "#". But such comments are not allowed in this file. The "comment" lines are treated as host names. Attempts to resolve these invalid host names through DNS result in very long delays. The user sees these long delays when he tries to run "rsh" or "rlogin" to the FreeBSD system. Whether the delays actually occur or not seems to depend on the behavior of the name server that is being used to process DNS queries. Sometimes the delays occur, and sometimes they do not. I *know* this is a problem, because I have observed the DNS queries for the bogus host names using an ethernet sniffer. And I have watched the timeouts occur as the name server failed to respond to the bogus queries. Furthermore, when I repaired the broken "/etc/hosts.equiv" file, the delays went away. >How-To-Repeat: 1. Use the default version of "/etc/hosts.equiv". 2. Specify a different machine as the name server in "/etc/resolv.conf". 3. Try to execute a command on the FreeBSD machine from a different machine, using "rsh". 4. You *may or may not* observe long delays. The problem seems to depend on the state of the name server. >Fix: Work-around: Eliminate comments and blank lines from "/etc/hosts.equiv". Simple fix: In the next release of the system, make sure there are no comments or blank lines in the default version of "/etc/hosts.equiv" that is created during system installation. I suggest either (a) not installing this file at all, or (b) installing an empty version of the file, or (c) installing a one-line version of the file, containing only "localhost". Better fix: Add code to __ivaliduser() in "/usr/src/lib/libc/net/rcmd.c" to make it ignore comment lines and blank lines. >Audit-Trail: >Unformatted:
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