Date: Tue, 29 Dec 1998 00:46:13 -0500 (EST) From: "Jasper O'Malley" <jooji@neptune.oceancomputer.com> To: FreeBSD-gnats-submit@FreeBSD.ORG, freebsd-bugs@FreeBSD.ORG Subject: Re: bin/9226: telnetd can log wrong IP address to utmp Message-ID: <Pine.BSF.4.02A.9812282242370.995-100000@neptune.oceancomputer.com> In-Reply-To: <199812282310.PAA17612@freefall.freebsd.org>
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I've found the easiest bit to fix to clear up the instant problem. In
src/libexec/telnetd/sys_term.c, a line reads:
int utmp_len = MAXHOSTNAMELEN;
It should probably read:
int utmp_len = UT_HOSTSIZE;
and should be moved after the #ifdef NEWINIT/#endif block (in which
utmp.h is included). The diff provided should work okay.
This will prevent telnetd from passing hostnames longer than UT_HOSTSIZE
on as arguments to "login -h", which is what gets the hostname relooked
up by login(1) in the first place. It doesn't appear this change will
break anything else, but I can't swear to it.
Better solutions would be to:
a) Make UT_HOSTSIZE bigger, which would break 4.4BSD utmp compatibility,
which isn't why it hasn't been done yet.
b) Rewrite/patch login(1), xterm(1), sshd(8) et al. to stop logging
hostnames in utmp altogether (how many people have hostnames less than
16 characters long these days?). Make other applications do the
reverse lookups later, a la w(1) and netstat(1).
Here's the patch:
*** /usr/src/libexec/telnetd/sys_term.c Wed Dec 24 14:23:18 1997
--- sys_term.c Mon Dec 28 23:05:37 1998
***************
*** 52,58 ****
# define PARENT_DOES_UTMP
#endif
- int utmp_len = MAXHOSTNAMELEN;
#ifdef NEWINIT
#include <initreq.h>
#else /* NEWINIT*/
--- 52,57 ----
***************
*** 99,104 ****
--- 98,109 ----
# endif /* _SC_CRAY_SECURE_SYS */
# endif /* CRAY */
#endif /* NEWINIT */
+
+ #ifdef UT_HOSTSIZE
+ int utmp_len = UT_HOSTSIZE;
+ #else
+ int utmp_len = MAXHOSTNAMELEN;
+ #endif /* UT_HOSTSIZE */
#ifdef STREAMSPTY
#include <sac.h>
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