The following code is from UNP
Code:
1 #include "ping.h"
2 void
3 send_v4 (void)
4 {
5 int len;
6 struct icmp *icmp;
7 icmp = (struct icmp *) sendbuf;
8 icmp->icmp_type = ICMP_ECHO;
9 icmp->icmp_code = 0;
10 icmp->icmp_id = pid;
11 icmp->icmp_seq = nsent++;
12 memset (icmp->icmp_data, 0xa5, datalen); /* fill with pattern */
13 Gettimeofday ((struct timeval *) icmp->icmp_data, NULL);
14 len = 8 + datalen; /* checksum ICMP header and data */
15 icmp->icmp_cksum = 0;
16 icmp->icmp_cksum = in_cksum ((u_short *) icmp, len);
17 Sendto (sockfd, sendbuf, len, 0, pr->sasend, pr->salen);
18 }
At line 12, why 0xa5 is used to fill icmp_data? Any good reason for doing so? Can I use something else to fill icmp_data