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準備一台 M300 方便跟 m330 做 gre tunnel keepalive 實驗
分別 build 最新的 code
m330[release/v0.08]
- Products/Vendor = GENERIC/0_GENERIC
M300[release/v2.02]
- Products/Vendor = M300/0_GENERIC
配置
+-------+ +-------+
| | lan | |
| m330 +-------------------------------------------+ M300 |
| | 192.168.1.33 192.168.1.30 | |
+-------+ +-------+
先來個最基本的 socket
- m330 送
- M300 收
study 一下 The Linux Programming Interface - Chapter 58: Sockets: Fundamentals of TCP/IP Networks
參考以下
m330
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdio.h>
int main() {
int sd;
struct sockaddr_in dest;
char msg[] = "Hello, World!";
dest.sin_family = AF_INET;
if (inet_pton(AF_INET, "192.168.1.30", &(dest.sin_addr)) != 1) {
printf("Bad Address!\n");
return(1);
}
if ((sd = socket(AF_INET, SOCK_RAW, 253)) < 0) {
printf("socket() failed!\n");
return(1);
}
if (sendto(sd, &msg, 14, 0, (struct sockaddr*) &dest, sizeof(struct sockaddr)) < 0) {
printf("sendto() failed!\n");
return(1);
}
return(0);
}M300
root@M300-S:~# tcpdump -X -s0 -i eth0
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth0, link-type EN10MB (Ethernet), capture size 262144 bytes
07:16:39.852368 IP 192.168.1.33 > 192.168.1.30: ip-proto-253 14
0x0000: 4500 0022 0000 4000 40fd b64f c0a8 0121 E.."..@[email protected]...!
0x0010: c0a8 011e 4865 6c6c 6f2c 2057 6f72 6c64 ....Hello,.World
0x0020: 2100 0000 0000 0000 0000 0000 0000 !.............
07:16:39.853090 IP 192.168.1.30 > 192.168.1.33: ICMP 192.168.1.30 protocol 253 unreachable, length 42
0x0000: 45c0 003e e1b5 0000 4001 14ba c0a8 011e E..>....@.......
0x0010: c0a8 0121 0302 bbd1 0000 0000 4500 0022 ...!........E.."
0x0020: 0000 4000 40fd b64f c0a8 0121 c0a8 011e ..@[email protected]...!....
0x0030: 4865 6c6c 6f2c 2057 6f72 6c64 2100 Hello,.World!.
2 packets captured
2 packets received by filter
0 packets dropped by kernel
試著讓 m330 送出 gre packet
可以參考 lunux 現成的 header file - <net/gre.h>