iOS - Get ARP table - ios

Question

I am trying to build a network scanner.
I know the procedure so I want to ping all available hosts in the network and then get the ARP table so I can map the MAC address for each IP.
I Googled for ARP table but I didn't find any guide how to implement this feature.
I also found these similar questions on Stack overflow:
Link1
Link2
The answer are unclear on how to implement the ARP feature.
Is there any official guide for this one? Is Apple approving the ARP table feature?

Answer 1

UPDATE AFTER 10.2
Check the library here
I finally got it working so I will post the procedure in detail to save some time for other guys:
Go to Applications and right click on Xcode -> Show package contents and browse to: Developer ▸ Platforms ▸ MacOSX.platform ▸ Developer ▸ SDKs ▸ MacOSX10.10.sdk ▸ usr ▸ include. From "net" folder copy the route.h and if_types.h and from the "netinet" folder copy the if_ether.h into your Xcode project.
Then import the following .m and .h files:
MacFinder.h
#import <Foundation/Foundation.h>
#include <sys/param.h>
#include <sys/file.h>
#include <sys/socket.h>
#include <sys/sysctl.h>
#include <net/if.h>
#include <net/if_dl.h>
#include "if_types.h"
#if TARGET_IPHONE_SIMULATOR
#include <net/route.h>
#else
#include "route.h"
#endif
#include "if_ether.h"
#include <netinet/in.h>
#include <arpa/inet.h>
#include <err.h>
#include <errno.h>
#include <netdb.h>
#include <paths.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#interface MacFinder : NSObject{
int nflag;
}
-(NSString*) ip2mac: (char*)ip;
#end
MacFinder.m
#import "MacFinder.h"
#implementation MacFinder
-(NSString*) ip2mac: (char*)ip
{
int found_entry = 0;
NSString *mAddr = nil;
u_long addr = inet_addr(ip);
int mib[6];
size_t needed;
char *host, *lim, *buf, *next;
struct rt_msghdr *rtm;
struct sockaddr_inarp *sin;
struct sockaddr_dl *sdl;
extern int h_errno;
struct hostent *hp;
mib[0] = CTL_NET;
mib[1] = PF_ROUTE;
mib[2] = 0;
mib[3] = AF_INET;
mib[4] = NET_RT_FLAGS;
mib[5] = RTF_LLINFO;
if (sysctl(mib, 6, NULL, &needed, NULL, 0) < 0)
err(1, "route-sysctl-estimate");
if ((buf = malloc(needed)) == NULL)
err(1, "malloc");
if (sysctl(mib, 6, buf, &needed, NULL, 0) < 0)
err(1, "actual retrieval of routing table");
lim = buf + needed;
for (next = buf; next < lim; next += rtm->rtm_msglen) {
rtm = (struct rt_msghdr *)next;
sin = (struct sockaddr_inarp *)(rtm + 1);
sdl = (struct sockaddr_dl *)(sin + 1);
if (addr) {
if (addr != sin->sin_addr.s_addr)
continue;
found_entry = 1;
}
if (nflag == 0)
hp = gethostbyaddr((caddr_t)&(sin->sin_addr),
sizeof sin->sin_addr, AF_INET);
else
hp = 0;
if (hp)
host = hp->h_name;
else {
host = "?";
if (h_errno == TRY_AGAIN)
nflag = 1;
}
if (sdl->sdl_alen) {
u_char *cp = LLADDR(sdl);
mAddr = [NSString stringWithFormat:#"%x:%x:%x:%x:%x:%x", cp[0], cp[1], cp[2], cp[3], cp[4], cp[5]];
// ether_print((u_char *)LLADDR(sdl));
}
else
mAddr = nil;
}
if (found_entry == 0) {
return nil;
} else {
return mAddr;
}
}
#end
Then import the MacFinder.h file in your ViewController
Example how to use it for each host you want to find the MAC Address:
MacFinder *mc = [[MacFinder alloc]init];
NSString *mac = [mc ip2mac:"192.168.10.24"];
NSLog(#"Mac:%#",mac);
If you still having trouble here is tutorial and here the full working project (Including the necessary files)