Hi, The guest is waiting a connect from the host and then tries to read what has been sent by the host. Both Guest and Host codes look like that : main() { int sock, msgsock, rval; struct sockaddr_un server; char buf[1024]; sock = socket(AF_UNIX, SOCK_STREAM, 0); if (sock < 0) { perror("opening stream socket"); exit(1); } server.sun_family = AF_UNIX; strcpy(server.sun_path, NAME); if (bind(sock, (struct sockaddr *) &server, sizeof(struct sockaddr_un))) { perror("binding stream socket"); exit(1); } printf("Socket has name %s\n", server.sun_path); listen(sock, 5); for (;;) { msgsock = accept(sock, 0, 0); if (msgsock == -1) perror("accept"); else do { bzero(buf, sizeof(buf)); if ((rval = read(msgsock, buf, 1024)) < 0) on the host side : main(argc, argv) .... sock = socket(AF_UNIX, SOCK_STREAM | SOCK_NONBLOCK, 0); if (sock < 0) { perror("opening stream socket"); return(1); } server.sun_family = AF_UNIX; strcpy(server.sun_path, argv[1]); if (connect(sock, (struct sockaddr *) &server, sizeof(struct sockaddr_un)) < 0) { close(sock); perror("connecting stream socket"); return(1); } if (write(sock, buffer, strlen(buffer)) < 0) perror("writing on stream socket"); Even if the host is not opening or sending anything I got this "already in use" error message. Regards, J.P. -----Message d'origine----- De : Martin Kletzander [mailto:mkletzan@redhat.com] Envoyé : mercredi 4 novembre 2015 16:21 À : Jean-Pierre Ribeauville Cc : libvirt-users(a)redhat.com Objet : Re: [libvirt-users] Retrieving datas sent by host within the Guest On Wed, Nov 04, 2015 at 02:38:43PM +0000, Jean-Pierre Ribeauville wrote: shouldn't you conect() instead of bind() ? Of course, open() should write as well.