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Date: Thu, 9 May 1996 22:10:37 -0400 (EDT)
From: Douglas Song <dugsong@umich.edu>
X-Sender: dugsong@laciotat.ifs.umich.edu
To: bugtraq@crimelab.com, best-of-security@suburbia.net,
        linux-security@tarsier.cv.nrao.edu
Subject: Patch for ytalk-3.2
Message-ID: <Pine.SOL.3.91.960509215702.11339A-100000@laciotat.ifs.umich.edu>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII
Sender: proff

Someone recently sent me a hacked ytalk client that spoofed the caller's
username, pretty lame. This is a patch to ytalk-3.2 to do detect such
spoofs via IDENT; really an abuse of the protocol, but what the heck. 
One lame hack deserves another. 

*** comm.c	Thu May  9 21:35:50 1996
--- comm.c.dug	Thu May  9 21:33:41 1996
***************
*** 601,606 ****
--- 601,622 ----
  	show_error("connect_user: bad read");
  	return;
      }
+ #ifdef USE_IDENT
+     {
+       char *ident = '\0';
+     
+       ident = ident_id(fd, 10);
+     
+       if (ident == '\0') {
+ 	strcat(user->full_name," (unverified)");
+       }
+       else if (strncmp(user->user_name, ident, NAME_SIZE) != 0) {
+ 	strcat(strcpy(user->full_name, user->user_name), "(");
+ 	strncat(user->full_name, ident, NAME_SIZE);
+ 	strcat(strcat(user->full_name, ")@"), user->host_name);
+       }
+     }
+ #endif /* USE_IDENT */
      if(open_term(user, user->full_name) < 0)
      {
  	free_user(user);
*** header.h	Thu May  9 21:35:44 1996
--- header.h.dug	Thu May  9 21:33:14 1996
***************
*** 31,36 ****
--- 31,39 ----
  #ifdef USE_X11
  # include <X11/X.h>
  #endif
+ #ifdef USE_IDENT
+ #include <ident.h>
+ #endif
  
  #define VMAJOR	3	/* major version number */
  #define VMINOR	0	/* minor version number */
*** Imakefile	Thu May  9 21:35:36 1996
--- Imakefile.dug	Thu May  9 21:41:11 1996
***************
*** 30,39 ****
  #SLIBS = -lsun
  
  #
! # If you are on a sun running solaris 2.* you might need to uncomment the 
! # following line.
  
  #SLIBS = -lnsl -lsocket
  
  #
  # If your machine has a 64-bit architecture or uses 64-bit 'long's, then you
--- 30,40 ----
  #SLIBS = -lsun
  
  #
! # If you are on a sun running solaris 2.* you need to uncomment the 
! # following lines.
  
  #SLIBS = -lnsl -lsocket
+ #SDEFS = -DSYSV
  
  #
  # If your machine has a 64-bit architecture or uses 64-bit 'long's, then you
***************
*** 56,66 ****
  Y_BINDIR = /usr/local/bin
  Y_MANDIR = /usr/local/man/man1
  
  ############################################################
  ## Past this point, you shouldn't need to modify anything ##
  ############################################################
! LIB = -lcurses -ltermcap $(SLIBS) $(XLIB)
! DEFINES = -DUSE_X11 -I/usr/local/include $(TDEFS) $(BDEFS) $(RCDEF)
  LDFLAGS = $(LDOPTIONS)
  OBJ = main.o term.o user.o fd.o comm.o menu.o socket.o rc.o exec.o cwin.o \
        xwin.o
--- 57,79 ----
  Y_BINDIR = /usr/local/bin
  Y_MANDIR = /usr/local/man/man1
  
+ # 
+ # Uncomment the and edit the following if you want ytalk to check
+ # the caller's name against the info given by his IDENT daemon. This
+ # is an abuse of the protocol, but oh well. Not everyone runs Zephyr.  
+ # libident available from ftp://ftp.lysator.liu.edu/pub/ident/libs
+ 
+ #IDEFS = -DUSE_IDENT
+ #ILIB = -L/usr/local/lib -lident
+ #IINC = -I/usr/local/include
+ 
+ 
  ############################################################
  ## Past this point, you shouldn't need to modify anything ##
  ############################################################
! LIB = -lcurses -ltermcap $(SLIBS) $(XLIB) $(ILIB)
! DEFINES = -DUSE_X11 -I/usr/local/include $(IINC) $(IDEFS) $(SDEFS) \
! 	  $(TDEFS) $(BDEFS) $(RCDEF)
  LDFLAGS = $(LDOPTIONS)
  OBJ = main.o term.o user.o fd.o comm.o menu.o socket.o rc.o exec.o cwin.o \
        xwin.o