Esa Hill wrote: > When nmap scan is executed against our device (LwIP 1.4.1), it responds with > RST for SYN even > when the socket/port is listening only UDP “connections”. > > Is this correct behavior (does some RFC say something about this?) or should > it just drop silently > the SYN packet as it does for unused ports? > This came up in one certification process (they see it as a problem).
Yes, this is correct behaviour. Any correct packet that does not match a pcb should be answered with RST (unless it is a RST itself). Not sending a RST in response is often done by devices to "hide" their presence, but I'm not sure this is really safer to do... Also I can't tell you right now if there is an lwIP setting to do so, but I think not. > Nmap results: > 49998/tcp filtered unknown > 49999/tcp filtered unknown > 50000/tcp closed ibm-db2 > 50001/tcp filtered unknown > 50002/tcp filtered iiimsf That's strange. You should see a RST on all ports. Unless you have a resource problem. As Sergio already said there is absolutely no interconnection between UDP and TCP. Simon _______________________________________________ lwip-users mailing list [email protected] https://lists.nongnu.org/mailman/listinfo/lwip-users
