[4495] in Athena Bugs
comp.bugs.4bsd: rlogind/BIND interaction
daemon@ATHENA.MIT.EDU (Jonathan I. Kamens)
Sun Mar 11 21:35:37 1990
Date: Sun, 11 Mar 90 21:35:25 -0500
From: Jonathan I. Kamens <jik@pit-manager.MIT.EDU>
To: bugs@ATHENA.MIT.EDU
In article <48750@wlbr.IMSD.CONTEL.COM>, sms@wlv.imsd.contel.com (Steven
M. Schultz) writes:
> Subject: rlogind/BIND undesireable interaction (+FIX)
> Index: etc/rlogind/rlogind.c 4.3BSD
>
> Description:
>
> The version of 'rlogind' is 5.22.1.7 dated 9/11/89, and the problem
> is in the "verification" process 'rlogind' performs to make sure
> the remote host is really himself.
>
> 'Rlogind' does a gethostbyaddr() to look up the name of the
> client host, receives a successfull response, and then
> performs a gethostbyname() using the name returned earlier.
>
> Unfortunately, there is not a trailing '.' at the end of
> the name returned by gethostbyaddr() and RES_DNSRCH (and RES_DEFNAME)
> are ON (by default), so the resolving routines merrily start appending
> the various domain subcomponents and issuing queries to the 'named'.
> In turn, 'named' can end up wandering out to the root servers before
> the domain search path is empty and a query on the ORIGINAL
> name is done (query ends up back in the local domain finally), at
> which point the 'rlogin' completes. Very slow! Especially if
> any network links/interfaces are down.
>
> Repeat-By:
> Probably the easiest way to see this is to turn on the debugging
> in the name servor with a SIGUSR1 and watch /usr/tmp/named.run.
>
> Alternatively, use 'nslookup' with RES_DEBUG turned on.
>
> Fix:
> Apply this patch to rlogind and reinstall rlogind.
>
> *** rlogind.c.old Fri Oct 6 17:29:38 1989
> --- rlogind.c Thu Mar 8 10:21:14 1990
> ***************
> *** 57,62 ****
> --- 57,64 ----
> #include <netdb.h>
> #include <syslog.h>
> #include <strings.h>
> + #include <arpa/nameser.h>
> + #include <resolv.h>
>
> #ifndef TIOCPKT_WINDOW
> #define TIOCPKT_WINDOW 0x80
> ***************
> *** 170,175 ****
> --- 172,185 ----
> */
> strncpy(remotehost, hp->h_name, sizeof(remotehost) - 1);
> remotehost[sizeof(remotehost) - 1] = 0;
> + #ifdef RES_DNSRCH
> + /*
> + * gethostbyaddr returns a FQDN, so now the domain search
> + * action must be turned off to avoid unwanted queries to
> + * the nameservor.
> + */
> + _res.options &= ~RES_DNSRCH;
> + #endif RES_DNSRCH
> hp = gethostbyname(remotehost);
> if (hp)
> #ifdef h_addr /* 4.2 hack */
Jonathan Kamens USnail:
MIT Project Athena 11 Ashford Terrace
jik@Athena.MIT.EDU Allston, MA 02134
Office: 617-253-8495 Home: 617-782-0710
