dennis@rlgvax.UUCP (Dennis Bednar) (10/25/85)
The arpdump.c program posted by Barry Shien, has been enhanced
to also print Timer and Flags for the ARP entries.
All of the mods I made are ifdefed by CCI and DPB.
Here is the new version:
-------------- arpdump.c ---------------------
#define CCI /* CCI needs this because of nlist() problems */
#define DPB /* new personal mods added to the original */
#ifdef DPB
/*
* arpdump.c
* Barry Shein, Boston University original 10 21 85
* Dennis Bednar, CCI Reston VA, added options, Timer, Flags, 10 25 85
*
* usage: arpdump [-a] [-v] [seconds]
* -a = print old timed-out slots too
* ie slots containing non-zero etheraddr && IP addr == 0
* -v = verbose, prints every entry in the table
* seconds = decimal seconds to print again
*
*/
#else
/*
usage: arpdump [seconds]
Newsgroups: net.unix-wizards
Subject: Re: Re: Ethernet problems
Re: Hedrick's suggestion that the problem may be with your ARP tables:
Here's a hack I use to examine the arp tables on my systems, I think
half of it or more is from something else, but it seems to do the job
(4.2bsd):
*/
#endif
#include <stdio.h>
#include <nlist.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
char *fcore = "/dev/kmem", *fnlist = "/vmunix" ;
struct nlist nl[] = {
#define ARPTAB 0
{ "_arptab" },
{ "" },
} ;
#ifdef DPB
/* The arptab structure is defined in netinet/if_ether.h */
#endif
struct arptab {
struct in_addr at_iaddr; /* internet address */
u_char at_enaddr[6]; /* ethernet address */
struct mbuf *at_hold; /* last packet until resolved/timeout */
u_char at_timer; /* minutes since last reference */
u_char at_flags; /* flags */
};
/* at_flags field values */
#ifdef DPB
/* The at_flags are defined in net/if.h */
#endif
#define ATF_INUSE 1 /* entry in use */
#define ATF_COM 2 /* completed entry (enaddr valid) */
#ifdef DPB
#define ATF_PERM 4 /* permanent entry */
#define ATF_PUBL 8 /* publish entry (respond for other host) */
#endif
#ifdef DPB
/* bucket stuff defined in netinet/if_ether.c */
#endif
#define ARPTAB_BSIZ 5 /* bucket size */
#define ARPTAB_NB 19 /* number of buckets */
#define ARPTAB_SIZE (ARPTAB_BSIZ * ARPTAB_NB)
struct arptab *arptab, atab ;
#ifdef DPB
int verbose; /* -v verbose flag */
int allflag; /* -a to print all timed out ones */
#endif
main(argc,argv) int argc ; char **argv ;
{
int fc ;
int i,j ;
int secs ;
char *ap ;
struct hostent *gethostbyaddr(), *hp ;
if((fc = open(fcore,0)) < 0)
{
perror(fcore) ;
exit(1) ;
}
#ifdef CCI
if (nlist(fnlist, nl) == -1)
{
fprintf(stderr, "arptab: nlist on %s returned error\n", fnlist);
exit(1);
}
#else
nlist(fnlist,nl) ;
#endif
arptab = (struct arptab *) nl[ARPTAB].n_value ;
#ifdef CCI
if (nl[0].n_value == 0)
#else
if(nl[0].n_type == 0)
#endif
{
fprintf(stderr,"No name list %s\n",fnlist) ;
exit(1) ;
}
#ifdef DPB
secs = 0;
/* primitive error checking on arguments */
for (i = 1; i < argc; ++i)
if (strcmp(argv[i], "-a") == 0)
++allflag;
else if (strcmp(argv[i], "-v") == 0)
++verbose;
else
secs = atoi(argv[i]);
#else
if(argc > 1) secs = atoi(argv[1]) ;
else secs = 0 ;
#endif
printf("\t\tACTIVE ARP TABLE DUMP\n") ;
loop:
#ifdef DPB
printf("Index\tIP Addr\t\tEthernet Interface\tHostName\tTimer\tFlags\n") ;
#else
printf("Index\tAddr\t\tEthernet Interface\tHostName\n") ;
#endif
lseek(fc,(int) arptab,0) ;
#ifdef DPB
ap = (char *) &atab;
#else
/* old way requires that at_iaddr be first */
ap = (char *) &atab.at_iaddr ;
#endif
for(i=0 ; i < ARPTAB_SIZE ; i++)
{
if(read(fc,&atab,sizeof atab) != (sizeof atab))
{
fprintf(stderr,"Error reading arp table\n") ;
exit(1) ;
}
#ifdef DPB
if (verbose)
goto printslot; /* print every slot it */
if (allflag) /* print old timed out "half-filled" slots */
if ( inet_netof(atab.at_iaddr) != 0 ||
atab.at_flags != 0 ||
ge_addr(&atab.at_enaddr[0]) != 0)
; /* print slot below */
else
continue;
else /* print only entries with IP addresses */
if (inet_netof(atab.at_iaddr) != 0)
; /* print slot below */
else
continue;
printslot:
#else
if(inet_netof(atab.at_iaddr) == 0) continue ;
#endif
printf("%2d:\t",i) ;
printf("%s\t",ap = (char *) inet_ntoa(atab.at_iaddr)) ;
#ifdef DPB
/* kludgy way to align columns because IP addr is var len */
if (strlen(ap)<8) printf("\t");
#endif
for(j=0 ; j < 6 ; j++)
printf("%02x",atab.at_enaddr[j]) ;
if((hp = gethostbyaddr(&atab.at_iaddr.s_addr,
sizeof atab.at_iaddr.s_addr,
AF_INET)) == NULL)
#ifdef DPB
/* save ptr to host name printed for strlen later */
printf(ap = "\t\t(unknown)") ;
else printf("\t\t%s",ap = hp->h_name) ;
#else
printf("\t\t(unknown)") ;
else printf("\t\t%s",hp->h_name) ;
#endif
#ifdef DPB
/* again kludgy way to align columns because hostname var len */
if (strlen(ap)<8) printf("\t");
printf("\t%3d", atab.at_timer);
printf("\t");
if (atab.at_flags & ATF_INUSE) printf("U");
if (atab.at_flags & ATF_COM) printf("C");
if (atab.at_flags & ATF_PERM) printf("P");
if (atab.at_flags & ATF_PUBL) printf("R"); /* responding */
#endif
printf("\n") ;
}
if(secs <= 0) exit(0) ;
sleep(secs) ;
goto loop ;
}
/*
-Barry Shein, Boston University
*/
#ifdef DPB
/*
* get ethernet address
* returns 0 iff 6 byte ethernet address is all zeros
*/
ge_addr(addr)
register char *addr;
{
register int i;
for (i = 0; i < 6; ++i, ++addr)
if (*addr)
return 1; /* found a non-zero byte */
return 0; /* all bytes were zero */
}
#endif
--
Dennis Bednar Computer Consoles Inc. Reston VA 703-648-3300
{decvax,ihnp4,harpo,allegra}!seismo!rlgvax!dennis