tcp server 

#include <stdio.h>

#include <netinet/in.h>

#include <unistd.h>

int main() {

int s = socket(AF_INET, SOCK_STREAM, 0);

struct sockaddr_in a = {AF_INET, htons(1234), INADDR_ANY};

bind(s, (void*)&a, sizeof(a));

listen(s, 1);

int c = accept(s, NULL, NULL);

char msg[100];

read(c, msg, 100);

printf("Client: %s\n", msg);

write(c, "Hi Client", 10);

close(c); close(s);

return 0;

}

tcp client 

#include <stdio.h>

#include <netinet/in.h>

#include <unistd.h>

#include <arpa/inet.h>

int main() {

int s = socket(AF_INET, SOCK_STREAM, 0);

struct sockaddr_in a = {AF_INET, htons(1234)};

inet_pton(AF_INET, "127.0.0.1", &a.sin_addr);

connect(s, (void*)&a, sizeof(a));

write(s, "Hi Server", 10);

char msg[100];

read(s, msg, 100);

printf("Server: %s\n", msg);

close(s);

return 0;

}

udp server

#include <stdio.h>

#include <netinet/in.h>

int main() {

int s = socket(AF_INET, SOCK_DGRAM, 0);

struct sockaddr_in a = {AF_INET, htons(1234), INADDR_ANY};

bind(s, (void*)&a, sizeof(a));

char msg[100];

struct sockaddr_in c;

socklen_t l = sizeof(c);

recvfrom(s, msg, sizeof(msg), 0, (void*)&c, &l);

printf("Client: %s\n", msg);

sendto(s, "Hi Client", 10, 0, (void*)&c, l);

return 0;

}

udp client 

#include <stdio.h>

#include <netinet/in.h>

#include <arpa/inet.h>

int main() {

int s = socket(AF_INET, SOCK_DGRAM, 0);

struct sockaddr_in a = {AF_INET, htons(1234)};

inet_pton(AF_INET, "127.0.0.1", &a.sin_addr);

sendto(s, "Hi Server", 10, 0, (void*)&a, sizeof(a));

char msg[100];

socklen_t l = sizeof(a);

recvfrom(s, msg, sizeof(msg), 0, (void*)&a, &l);

printf("Server: %s\n", msg);

return 0;

}