linux - How to get sender IP of a desired broadcast address:port combination? -

i see broadcast packets on wireshark i'd able check on using simple linux command-line utility. this:

getsenders bcast_ip port timeout 

and print each new sender ip encountered during timeout period.

for example:

getsenders 192.168.0.255 12345 0.150 

or (alternatively)

getsenders 192.168.0.0/8 12345 0.150 

would listen broadcast packets sent 192.168.0.255:12345, print each unique sender encountered. alternate approach listed broadcast senders on specified interface.

unfortunately, socket-fu weak. know program must run root permissions (suid) listen on broadcast socket.

i've put in lots of time (days) trying python, looks route require using raw socket , parsing packets (a packet sniffer, ugh!). looked @ using socat/netcat (via execute-only suid bash script) got nowhere.

is there simple linux code available me? don't care tool or source language is, long can set suid-root , run command line.

btw, have simple python solution works under ms windows dies under linux:

myip = <ip address of local interface listen on> p = <broadcast port> timeout = 0.150    # 150 ms addresses = {}  if "windows" in sys.platform.tolower():     # create broadcast reception socket     bsock = socket.socket(socket.af_inet, socket.sock_dgram)     bsock.setsockopt(socket.sol_socket, socket.so_reuseaddr, 1)     bsock.setsockopt(socket.sol_socket, socket.so_broadcast, 1)     bsock.settimeout(timeout)     bsock.bind((myip, p))     while true: # senders         try:             __, address = bsock.recvfrom(1024)   # don't care payload         except baseexception, e:             break   # nothing found         else:   # desired broadcast packet detected             if address[0] not in addresses:                 addresses[address[0]] = 1             else:                 addresses[address[0]] += 1                 if addresses[address[0]] >= 3:                     break   # go until timeout or sender seen 3 times         finally:             bsock.close()             bsock = none             print(', '.join([k k in addresses])) 

after downloading , testing many examples, got working, bisected , combined code until had minimal difference worked on both platforms.

it came down 1 line: linux must bind specific broadcast address (as root), windows can bind local interface address (as normal user) broadcast packets expected arrive.

here's revised code snippet:

bcast_addr = <ip addr of broadcast: must end @ least 1 '.255'> myip = <ip addr of local interface receiving bcast_addr> p = <broadcast port> timeout = 0.150    # 150 ms addresses = {}  # create broadcast reception socket bsock = socket.socket(socket.af_inet, socket.sock_dgram) bsock.setsockopt(socket.sol_socket, socket.so_reuseaddr, 1) bsock.setsockopt(socket.sol_socket, socket.so_broadcast, 1) bsock.settimeout(timeout) if "windows" in sys.platform.tolower():     bsock.bind((myip, p)) elif os.getuid() == 0:  # must root linux!     bsock.bind((bcast_addr, p)) while true: # senders     try:         __, address = bsock.recvfrom(1024)   # don't care payload     except baseexception, e:         break   # nothing found     else:   # desired broadcast packet detected         if address[0] not in addresses:             addresses[address[0]] = 1         else:             addresses[address[0]] += 1             if addresses[address[0]] >= 3:                 break   # go until timeout or sender seen 3 times     finally:         bsock.close()         bsock = none         print(', '.join([k k in addresses]))