Run tcpdump on local interface.
tcpdump -i lo
cheers
ashley
On Tue, 13 Nov 2001, Chunhua Zhao wrote:
> Hello,
>
> I am a new user of tcpdump. I found that if the server and client
> application run on the same machine, tcpdump cannot catch the packets
> transferred between them. Can anyone tell me the reason? Any suggestions
> will be appreciated.
>
> The following is part of the test programs I used:
>
> //--------TCP server--------------------------
> struct hostent *hostinfo;
> struct sockaddr_in listener;
>
> lsockFd = socket(AF_INET, SOCK_STREAM, 0);
> listener.sin_family = AF_INET;
> listener.sin_addr = **(struct in_addr **)hostinfo->h_addr_list;
> listener.sin_port=0;
> if (bind(lsockFd, (struct sockaddr *)&listener, sizeof(listener))<0){
> perror("bind listen:"); exit(1);
> }
> size=sizeof(listener);
> getsockname(lsockFd,(struct sockaddr*)&listener,(socklen_t *)&size);
> listen(lsockFd,10);
>
> // write information to a file so that the client can know the server
> information
>
> while(1){
> length = sizeof(from_tcp);
> tmpsock = accept(lsockFd,(struct sockaddr *)&from_tcp,&length);
> forkret_tcp = fork();
> if (forkret_tcp<0){ perror("Fork"); exit(-1);}
> if (forkret_tcp == 0) {
> close(lsockFd);
> tcp_procedure (tmpsock);
> exit(0);
> }
> ....
> }
>
> //-----------TCP client-----------
>
> struct sockaddr_in listener;
>
> // read server information from the file, so that listener has
> appropriate value
>
> qfd = socket(AF_INET,SOCK_STREAM,0);
> if (connect(qfd,&listener,sizeof(listener))<0)
> perror("connect:");exit(1);}
>
> FD_ZERO(&mask); FD_SET(qfd, &mask);
> timeout.tv_sec = 20;
> timeout.tv_usec = 0;
> if ((hits = select(qfd+1, (fd_set *)0, &mask,(fd_set *)0, &timeout)) <
> 0) {
> perror("client: TCP/IP select"); exit(1);
> }
> ....
>
>
> thanks
> Chunhua
>
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