Howto transmit RAW packets out of /dev/sl0

Howto transmit RAW packets out of /dev/sl0

Post by Richard van Ulde » Thu, 24 Feb 2000 04:00:00


I need to transmit & receive RAW packets (proprietary protocol)  in a
SLIP kind of fashion.

The packets are not IP and just need the SLIP_END, SLIP_ESC etc

My idea is to use /dev/sl0 as implemented in the kernel,
for SLIP encapsulation of these RAW packets.

What I do now is the following :
(Code basics)

Open /dev/ttyS0
Initialize this port for correct speed etc.

fd = file descriptor /dev/ttyS0

/* Set Line Discipline to SLIP */
disc = N_SLIP;
if (ioctl(Fd, TIOCSETD, &disc) < 0)              
   Exit (1);

/* Disable VJ compression */
encap = 0x0000;
if (ioctl(Fd, SIOCSIFENCAP, &encap) < 0)
   Exit (1);

/* Get the interface name */
if (ioctl (f,SIOCGIFNAME,&interface) < 0)

/* Show it */
printf ("interface name %s\n",interface);

/* init interface struct */
memset (&ifr,0,sizeof(ifr));
strcpy (ifr.ifr_name,interface);

/* open a socket */
sd = socket (PF_INET,SOCK_RAW, htons (0x00FF));
if (sd < 0)

/* connect interface to socket */
if (ioctl (sd,SIOCSIFFLAGS,&ifr) < 0)

strcpy (buf_out,"Hello World\n");

memset (&address,0,sizeof(struct sockaddr));
address.sa_family= AF_UNSPEC;

n = sendto (sd,buf_out, strlen(buf_out),0,
                   &address,sizeof(struct sockaddr) );

n returns (12) but nothing is comming out of  the SLIP port
Why Not ????????

Questions :
   Does anyone have code examples of something similar.???
   Anyone who can add serious comment to code basics above?
   What am I doing wrong?

Note that :
  Packet sniffers only monitor and do not write to interfaces.

Thanks in advance for your time and interest looking into this.


Richard van Ulden

Put the line discipline for this device  to SLIP

Open a socket for interface sl0 in RAW mode.


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