OpenSS7: SS7 RAW Sockets

NAME	SOCKET OPTIONS	SEE ALSO	RESTRICTIONS
SYNOPSIS	IOCTLS	NOTES	AUTHOR
DESCRIPTION	ERROR HANDLING	CAVEATS	HISTORY
ADDRESS FORMATS	ERRORS	DIAGNOSTICS	REFERENCES
SYSCTLS	EXAMPLES	BUGS

ss7raw - Linux SS7 raw sockets

#include <sys/socket.h>
#include <netss7/ss7.h>
raw_socket = socket(PF_SS7, SOCK_RAW, protocol);

Raw SS7 sockets permit ferry clip testing and other experimentation with the SS7 protocols in user space. A raw SS7 socket sends ore receives SS7 PDUs without invoking the protocol state machine at the specified protocol level and permits simulation and protocol testing.

Only processes with an effective user id of 0 or the CAP_NET_RAW capability are allowed to open raw sockets.

All primitives, PDUs or errors matching the protocol number specified for the raw socket are passed to this socket.

Raw SS7 sockets depend on the protocol specified. The following protocol values are allowed:

SS7_PROT_LINK: This socket provides for the exchange of primitives and PDUs below the SS7 Link Level state machines (i.e. directly with the SS7 Link Interface). The socket will generate its own Link Level header (FSN/FIB, BSN/BIB, and LI) when sending PDUs on the socket unless the SS7_HDRINCL socket option is enabled on the socket.
SS7_PROT_NTWK: This socket provides for the exchange of primitives and PDUs below the SS7 Network Level state machines (i.e., directly with the SS7 Link Level state machines). The socket will generate an SS7 Routing Label when sending a PDU unless the SS7_HDRINCL socket option is enabled on the socket.

Level 2 Header Fields Modified on Sending
Field	Action
FSN/FIB	Supplied by socket
BSN/BIB
LI	Calculated by socket

Level 3 Header Fields Modified on Sending
Field	Action
SI	Supplied by user
NI
MP
DPC	Socket destination address when socket is bound, otherwise, supplied by user.
OPC	Selected by MTP Routing
SLS	Selected by MTP State Machine

In OpenSS7 for Linux 2.2 all SS7 header fields and characteristics can be controlled using SS7 socket options, sysctls and ioctls. This means that raw SS7 sockets are usually only needed for simulation and testing.

When a packet is received, it is passed to any raw sockets which have been bound to its protocol before it is passed to other protocol handlers (e.g. kernel protocol modules).

Raw SS7 sockets uses the SS7 sockaddr_ss7 address structure described in ss7(2).

The following sysctls can be accessed by the /proc/sys/net/ss7/*/* files or with the sysctl(2) interface:

RAW SS7 sockets have no raw socket specific systclts at this time.

To set or get a socket option, call getsockopt(2) to read or setsockopt(2) to write the option with the socket family argument set to SOL_RAW. In addition, all SOL_SS7 socket options are valid on raw sockets. For more information see ss7(7).

There are not socket options specific to raw SS7 sockets at this time.

All of the ioctls described in socket(7) apply to SS7. The ioctls to configure gateway screening are documented in gws(7) from the bgws package. Ioctls to configure generic device parameters and described in ss7device(7). All of the ioctls which are described in ss7(7) are also applicable to raw sockets.

There are no raw socket specific ioctls at this time.

Errors originating from the network are only passed to the user when the socket is connected or the SS7_RECVERR flag is enabled. For connected sockets only EMSGSIZE and EPROTO are passed for compatibility. With SS7_RECVERR all network errors are saved in the error queue.

EMSGSIZE: SS7 raw sockets do not return this error. This is because it is intended for testing and the user may send an intentionally long packet.
EPROTO: An error has arrived reporting a parameter problem.
EFAULT: An invalid memory address was supplied.
EOPNOTSUPP: Invalid flag has been passed to a socket call (like MSG_OOB).
EINVAL: Invalid argument.
EPERM: The user doen't have permission to open raw sockets. Only processes with an effective user id of 0 or the CAP_NET_RAW capability can do that.

ss7(7), link(7), ss7device(7), gws(7), socket(7), raw(7), ip(7), udp(7), sysctl(2), getsockopt(2), setsockopt(2), socket(2), bind(2), connect(2), accept(2), listen(2), sendto(2), sendmsg(2), recvmsg(2), send(2), write(2), ioctl(2), htonl(2).

A raw socket can be bound to a specific local address using the bind(2) call. If it isn't bound all packets with the specified SS7 protocol are received. In addition a RAW socket can be bound to a specific SS7 interface device using SO_BINDTODEVICE; see socket(7).

An IPPROTO_RAW socket is send only. If you really want to receive all SS7 packets use a packet(7) socket with the ETH_P_SS7 protocol.

If you want to receive all SNTM PDUs for an MTP socket it is often better to use SS7_RECVERR on that particular socket; see ss7(7).

Raw sockets may tap all SS7 protocols in Linux, even protocols like MTP or SCCP which have a protocol module in the kernel. In this case the packets are passed to both the kernel module and the raw socket(s). This should not be relied upon in portable programs, other BSD socket implementation have differences here.

Linux never changes headers passed from the user when SS7_HDRINCL is enabled (except for filling in some zeroed fields as described for SS7_HDRINCL). This may differ from other implementations of raw sockets for SS7.

RAW sockets are generally rather unportable and should be avoided in programs intended to be portable.

Sending on raw sockets should take the IP protocol from sin_port; this ability was lost in Linux 2.2. Work around is to use IP_HDRINCL.

As this is an ALPHA (experimental) release. As such, there are probably many unknown bugs.

The SS7 raw packet capability was intended for testing the protocol implementation itself. Aside from protocol testing and test or simulation application, raw SS7 sockets serve no purpose.

OpenSS7, <openss7@openss7.org>.

This man page borrows literally and heavily from the raw(7) man page for Linux written by Andi Kleen <ak@muc.de>.

OpenSS7 was implemented first for Linux for the Linux 2.2 kernels.

ITU-T Rec. Q.700, Introduction to CCITT Signalling System No. 7,
ITU-T Rec. Q.701, Functional description of the message transfer part (MTP),
ITU-T Rec. Q.702, Signalling data link,
ITU-T Rec. Q.703, Signalling link,
ITU-T Rec. Q.704, Signalling network functions and messages,
ITU-T Rec. Q.705, Signalling network structure,
ITU-T Rec. Q.706, Message transfer part signalling performance,
ITU-T Rec. Q.707, Testing and maintenance,
ITU-T Rec. Q.708, Assignment procedures for international signalling point codes,
ITU-T Rec. Q.709, Hypothetical signalling reference connection,
ITU-T Rec. Q.710, Simplified MTP for small systems