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New Member

broadcasts

Hi all, I know with broadcasts you have arp etc, can you have TCP, and UDP broadcasts, wha do they look like on a sniffer ?

4 REPLIES
New Member

Re: broadcasts

You can see UDP broadcast with protocols such as DHCP. For both tcp and udp you should see an entry in you sniffer to x.x.x.255 or 255.255.255.255

New Member

Re: broadcasts

hi there, can you give me another example of this? what kind of apps would have a tcp/udp broadcast?

New Member

Re: broadcasts

Hello Carl,

UDP broadcasts are sent by DNS, NETBIOS, Spanning-Tree,DHCP...again i do not think that TCP sends a Broadcast

New Member

Re: broadcasts

Hello Carl,

I my opinion we do have UDP Broadcasts but TCP dosen't Broadcast by itself. TCP is a connection oriented protocol and would always try to Synchronise the connection (the SYN and ACK method)...but broadcasts can happen with TCP but TCP itself dosent initiate the broadcast. A device eg a switch with no matching destination MAC in the MAC-Address-Table can broadcast the TCP Packet or a hub can broadcast it..and if the destination ip address of the a Packet (TCP) is 255.255.255.255 then it may be broadcasted by a router or a multilayer switch and that too can be restricted by "no ip directed-broadcast" command...I would like some expert to trow some more info...

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