1. Training
2018/10/11

2. Scenario

3. Router Crossover IP forward Route Backdoor 鳥哥的 Linux 私房菜
Route
d.php#route
Backdoor

4. 第1題
As shown in the above figure, set up a 2-port Linux PC Router and install Linux open source VoIP (Asterisk or Linphone) and video streaming server (Darwin or VLC) on PC1 and PC2. Use microphones and MPEG-4 clips to examine whether you have installed Asterisk/Linphone and Darwin/VLC successfully.
<Note>: you need two Ethernet cards and two crossover UTP cables to form a router network.

5. Application
VOIP
Asterisk
Video streaming
Darwin
TCP Socket

6. VOIP Installation (1/7)
Run "./configure"

7. Installation (2/7)
Run "make menuselect" [optional]

8. Installation (3/7)
Run "make"

9. Installation (4/7)
Run "make install"

10. Installation (5/7) Finally, you can launch Asterisk with:
# asterisk –vvvc

11. Installation (6/7)
You can type "core show help" at any time to get help with the system.

12. Installation (7/7)

13. Starting Asterisk Install softphone /etc/asterisk/sip.conf
/etc/asterisk/extensions.conf 
Install softphone
ex:Linphone, X-lite

14. VOD Server : Darwin (5.5.5) Client : VLC player
MP4Box : Mp4 hint track
rtsp:// /example.mp4

15. Installation tar zxf DarwinStreamingSrvr5.5.5-Linux.tar.gz
cd DarwinStreamingSrvrlinux-Linux
./Install
Please enter a new administrator user name: user_name
Please enter a new administrator Password: your_password

16. Starting sudo /usr/local/sbin/DarwinStreamingServer
sudo /usr/local/sbin/streamingadminserver.pl

17. 第2題
Write down client/server programs by using TCP socket. Your client/server programs must work with Asterisk/Linphone (VoIP) and Darwin/VLC (VoD) and it must allow two users to send and receive English/Chinese text messages (ASCII code) to each other.

18. TCP socket

19. TCP socket server

20. TCP socket client

21. module Use makefile to compile the program
make all
Insert program to the kernel module
insmod input_queue.ko
rmmod input_queue
lsmod

22. IP header

23. TCP/ UDP header

24. RTP Header

25. IP Layer
int count(struct sk_buff* skb){ struct iphdr *iph; struct tcphdr *tcph; struct udphdr *udph; struct timeval tv; static int total_packet = 0; static int last_timestamp = 0;

26. IP Layer
iph = skb->nh.iph; printk("=================IP=================\n"); //IP Header printk("Version = %d\n",iph-> version); printk("IHL = %d\n",iph-> ihl*4); printk("Type of Service = %d\n",iph-> tos); printk("Total Length = %d\n",ntohs(iph-> tot_len)); printk("Identification = %d\n",iph-> id); printk("Fragmentation Offset = %d\n",iph-> frag_off); printk("Time to live = %d\n",iph-> ttl); printk("Protocol = %d\n",iph-> protocol);

27. IP Layer
printk("Header Checksum = 0x%x\n",iph-> check); printk("Source Address = %d.%d.%d.%d\n",*(skb->nh.raw+12),*(skb->nh.raw+13),*(skb->nh.raw+14),*(skb->nh.raw+15)); printk("Distination Address = %d.%d.%d.%d\n",*(skb->nh.raw+16),*(skb->nh.raw+17),*(skb->nh.raw+18),*(skb->nh.raw+19));

28. TCP Layer
if(iph-> protocol == IPPROTO_UDP) {//UDP Header printk("================UDP=================\n"); udph = (struct udphdr *)(skb->nh.raw + iph->ihl*4); printk("Source Port = %d\n",ntohs(udph->source)); printk("Distination Address = %d\n",ntohs(udph-> dest)); printk("Segment Length = %d\n",ntohs(udph-> len)); printk("Checksum = 0x%x\n",udph-> check);

29. 第3題
On Linux router
(1) Write down a backdoor program on the router to measure the average packet forwarding delay for Darwin/VLC video streaming. Packet forwarding delay is defined from the time when sk_buff is constructed for the packet untill the time when the packet is removed from sk_buff.

30. 第3題
On PC-1/PC-2
(2) Write down a backdoor program on PC-1/PC-2 to measure average throughput for Asterisk/Linphone and Darwin/VLC, respectively. Compare their differences.
(3) Intercept IP packets on client/server and count how many packets generated for different sizes of text messages (e.g., 10, 50, 100 English/Chinese words).

31. /usr/src/kernels/fedora/include/linux/skbuff.h
Backdoor program
/usr/src/kernels/fedora/include/linux/skbuff.h

32. Defined as a function in: net/ipv4/ip_input.c, line 379
Defined as a function prototype in: include/net/ip.h, line 93
Referenced (in 3 files total) in: include/net/ip.h, line 93
net/ipv4/af_inet.c, line 1560
net/ipv4/ip_input.c, line 379

33. Backdoor program(1/2)
/usr/src/kernel/linux /net/ipv4/ip_input.c

34. Backdoor program(2/2)
/usr/src/kernel/linux /net/ipv4/ip_output.c

35. int (. input_queue)(struct sk_buff
int (*input_queue)(struct sk_buff *skb)=0; EXPORT_SYMBOL(input_queue); if(input_queue) { input_queue(skb); } int (*output_queue)(struct sk_buff *skb)=0; EXPORT_SYMBOL(output_queue); if(output_queue) output_queue(skb);

36. Kernel setup Compile linux kernel make all make modules_install
make install

37. AWK

38. Due Day Demo (three in a team) on Nov 7-10, 2018.
Report (individual, 15 pages) due before 9:00pm on Nov 12, 2018.