[asterisk-ss7] using dahdi as an E1 sniffer

[Horacio J. Peña]

I'm working on replacing an old ss7 to isdn converter with asterisk but
both libss7 and chanss7 fail to work on this link, with this system I
can let the link work with the old converter (and get dumps on how it works) 
during work hours and then stop the bridging and test the ss7 code while
the link is unused.

On Fri, Apr 30, 2010 at 08:31:41PM -0700, Bryan Scott wrote:
> What about just as a sniffer, I.e. Not having to interrupt a circuit
> to put in the bridge, but maybe as an analyzer on a monitor port?
> 
> On Friday, April 30, 2010, Horacio J. Peña <horape at compendium.com.ar> wrote:
> > Answering myself, hope it is useful for somebody:
> >
> > #include <sys/types.h>
> > #include <sys/stat.h>
> > #include <fcntl.h>
> > #include <errno.h>
> > #include <stdio.h>
> > #include <stdlib.h>
> > #include "dahdi-user.h"
> >
> > main()
> > {
> > int fds[62];
> > char fn[1024];
> > int i;
> > int BS=160;
> > char buf[BS];
> >
> > for (i=0;i<62;++i) {
> >   int c = i+1;
> >   if( (fds[i] = open("/dev/dahdi/channel", O_RDWR)) < 0) {
> >     printf("Error abriendo %s: %s\n", fn, strerror(errno));
> >     exit(1);
> >     }
> >   if (ioctl(fds[i], DAHDI_SPECIFY, &c) == -1) {
> >     printf("Error ioctl SPE %d: %s\n", i, strerror(errno));
> >     exit(1);
> >     }
> >   if (ioctl(fds[i], DAHDI_SET_BLOCKSIZE, &BS) == -1) {
> >     printf("Error ioctl BS %d: %s\n", i, strerror(errno));
> >     exit(1);
> >     }
> >   }
> >
> > while (read (fds[0], buf, BS)) {
> >   write (fds[31], buf, BS);
> >   for (i=1;i<62;++i) {
> >     read (fds[i], buf, BS);
> >     write (fds[(i+31)%62], buf, BS);
> >     }
> >   }
> > }
> >
> >
> >
> >
> > On Fri, Apr 30, 2010 at 12:58:02PM -0300, Horacio J. Peña wrote:
> >> Hola!
> >>
> >> Is there any app that would allow two E1s to be "bridged" so I can
> >> intercept a link and use dahdi pcap to analyze the traffic? (does dahdi
> >> pcap work for audio/pri channels or only ss7?)
> >>
> >> If there isn't, would something like this work?
> >>
> >> main()
> >> {
> >> int fds[64];
> >>
> >> // open channels as rw, E1 1 in fds[0..31], E1 2 in fds[32..63]
> >>
> >> int BS = 1;
> >> char buf[BS];
> >>
> >> while (read (fds[0], buf, BS) {
> >>   write (fds[32], buf, BS);
> >>   for (i=1;i<64;++i) {
> >>     read (fds[i], buf, BS);
> >>     write (fds[(i+32)%64], buf, BS);
> >>     }
> >>   }
> >> }
> >>
> >> (this uses fds[0] as clocking)
> >>
> >> How many bytes at once (BS) should I read/write? Should I do something
> >> very different? (It has been a long time since I worked with zap cards)
> >>
> >> Thanks!
> >> --
> >> Horacio J. Peña
> >> horape at compendium.com.ar
> >> horape at uninet.edu
> >
> > --
> > Horacio J. Peña
> > horape at compendium.com.ar
> > horape at uninet.edu
> >
> > --
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-- 
Horacio J. Peña
horape at compendium.com.ar
horape at uninet.edu