From owner-freebsd-current Thu Jan 18 19:31: 0 2001 Delivered-To: freebsd-current@freebsd.org Received: from mailhost01.reflexnet.net (mailhost01.reflexnet.net [64.6.192.82]) by hub.freebsd.org (Postfix) with ESMTP id 827F037B69B; Thu, 18 Jan 2001 19:30:41 -0800 (PST) Received: from rfx-216-196-73-168.users.reflexcom.com ([216.196.73.168]) by mailhost01.reflexnet.net with Microsoft SMTPSVC(5.5.1877.197.19); Thu, 18 Jan 2001 19:28:39 -0800 Received: (from cjc@localhost) by rfx-216-196-73-168.users.reflexcom.com (8.11.1/8.11.0) id f0J3UPa75677; Thu, 18 Jan 2001 19:30:25 -0800 (PST) (envelope-from cjc) Date: Thu, 18 Jan 2001 19:30:25 -0800 (PST) Message-Id: <200101190330.f0J3UPa75677@rfx-216-196-73-168.users.reflexcom.com> To: FreeBSD-gnats-submit@freebsd.org Subject: syslogd(8) does not update hostname From: cjclark@reflexcom.com Reply-To: cjclark@alum.mit.edu Cc: current@freebsd.org X-send-pr-version: 3.113 Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG >Submitter-Id: current-users >Originator: Crist J. Clark >Organization: >Confidential: no >Synopsis: syslogd(8) does not update hostname >Severity: non-critical >Priority: medium >Category: bin >Release: FreeBSD 5.0-CURRENT i386 >Class: sw-bug >Environment: All standard FreeBSD distributions. The code discussed is from 5.0-CURRENT, but should trivially merge back to -STABLE. >Description: Many tools and progams within FreeBSD date back to a time when it was expected that a machines IP and hostname seldom, if ever, changed. Even when a IP and hostname were received at boot, it rarely changed until shutdown. With many users using protocols like DHCP where IP and hostname change with time, many tools do not deal well with this behavior. One of these tools is syslogd(8). syslogd(8) is typically started at boot time and runs until shutdown. However, syslogd(8) loads the hostname at startup and syslogd(8)'s idea of the hostname can never change while it is running. One might expect that a SIGHUP would cause syslogd(8) to load the new hostname since a SIGHUP can cause syslogd(8) to re-read its configuration file and re-open the log files, but it does not. The fact that the hostname does not change can cause confusion in the log files. It could be especially troublesome when a machine is logging to a central loghost. At any given time, the names in the log files may not have any correspondence to the names the hosts currently have. There are even issues on a host that gets its IP and hostname via DHCP at boot and the name never changes. syslogd(8) is started before any network services are initialized in /etc/rc. I propose that syslogd(8) should reload the hostname with a SIGHUP. I cannot think of any reason that one should not update the hostname, but as I pointed out, there are reasons why one would want that behavior. >How-To-Repeat: # hostname -s bubbles # hostname bubbles-test.domain.org # kill -HUP `cat /var/run/syslog.pid` # logger -p user.notice "hostname test" # tail -4 /var/log/messages Jan 17 21:45:00 bubbles /boot/kernel/kernel: acd0: CDROM at ata0-slave using BIOSPIO Jan 17 21:45:00 bubbles /boot/kernel/kernel: Mounting root from ufs:/dev/ad0s1a Jan 18 00:41:14 bubbles su: cjc to root on /dev/ttyp0 Jan 18 00:58:34 bubbles cjc: hostname test >Fix: I do not see any reason we cannot move the code that gets the hostname from the main() function into init(). init() is called when to "reload" settings. The hostname is never used in main() before init() is called. The patch is against -CURRENT and my box has not exploded yet. Here is what the above test looks like with the change in place. # hostname -s bubbles # hostname bubbles-test.cjclark.org # kill -HUP `cat /var/run/syslog.pid ` # logger -p user.notice "syslogd hostname test" # hostname bubbles.cjclark.org # kill -HUP `cat /var/run/syslog.pid ` # logger -p user.notice "syslogd hostname test" # tail -4 /var/log/messages Jan 18 13:36:58 bubbles su: BAD SU cjc to root on /dev/ttyp0 Jan 18 13:37:03 bubbles su: cjc to root on /dev/ttyp0 Jan 18 13:38:40 bubbles-test cjc: syslogd hostname test Jan 18 13:39:11 bubbles cjc: syslogd hostname test --- syslogd.c 2001/01/18 08:06:34 +++ syslogd.c 2001/01/18 08:09:23 @@ -395,12 +395,6 @@ consfile.f_type = F_CONSOLE; (void)strcpy(consfile.f_un.f_fname, ctty + sizeof _PATH_DEV - 1); - (void)gethostname(LocalHostName, sizeof(LocalHostName)); - if ((p = strchr(LocalHostName, '.')) != NULL) { - *p++ = '\0'; - LocalDomain = p; - } else - LocalDomain = ""; (void)strcpy(bootfile, getbootfile()); (void)signal(SIGTERM, die); (void)signal(SIGINT, Debug ? die : SIG_IGN); @@ -1342,6 +1336,16 @@ char host[MAXHOSTNAMELEN+1]; dprintf("init\n"); + + /* + * Load hostname (may have changed) + */ + (void)gethostname(LocalHostName, sizeof(LocalHostName)); + if ((p = strchr(LocalHostName, '.')) != NULL) { + *p++ = '\0'; + LocalDomain = p; + } else + LocalDomain = ""; /* * Close all open log files. 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