ann kok wrote:

Hi all

The machine provides the name service

I got the following in the dmesg.

What is it?

Can I have rules to prevent it?

UDP: bad checksum. From outside-ip:61479 to machine-ip:61 ulen 45 UDP: bad checksum. From outside-ip:62499 to machine-ip:61 ulen 45 UDP: bad checksum. From outside-ip:64135 to machine-ip:61 ulen 45 UDP: bad checksum. From outside-ip:64135 to machine-ip:61 ulen 45 UDP: bad checksum. From outside-ip:65383 to machine-ip:61 ulen 45

outside-ip sent an invalid ICMP type 3, code 3 error to a broadcast: 248.32.x.x on eth0 outside-ip sent an invalid ICMP type 3, code 3 error to a broadcast: 248.32.x.x on eth0 outside-ip sent an invalid ICMP type 3, code 3 error to a broadcast: 248.32.x.x on eth0

'outside-ip', is that the IP of this system, or some random external internet IP, or what? odd, 248.32.x.x isn't a broadcast or multicast address AFAIK, is that part of one of your subnets or something?

I'm not sure what udp/61 is, /etc/services says 'NI-MAIL', that appears to be something from the dusty basement of pre-internet networking ("JNT mail over NIFTP").

ICMP type 3 code 3 is 'port unreachable'. see: http://www.iana.org/assignments/icmp-parameters if you block those you won't be able to do traceroutes.

if you just got a few of those, I'd ignore them. if you got lots and lots, it may be a weak attempt at a denial of service attack

anyways, dunno why you'd need any rules, the kernel rejected those packets on the grounds given.