CentOS - Apr 2015 - Explanation please?

I am seeing log file entries like this:

IN=eth0 OUT=eth1 SRC=109.74.193.253 DST=x.y.z.34 LEN=122 TOS=0x00
PREC=0x00 TTL=48 ID=49692 PROTO=ICMP TYPE=3 CODE=3 [SRC=x.y.z.34
DST=109.74.193.253 LEN=94 TOS=0x00 PREC=0x00 TTL=53 ID=41330 PROTO=UDP
SPT=34679 DPT=53 LEN=74 ]

This is found on our gateway host.  eth0 is the WAN i/f, eth1 is the
LAN i/f.  Our netblock is x.y.z.0/24.  Can somebody tell me what this
record is?


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James B. Byrne                mailto:ByrneJB at Harte-Lyne.ca
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Canada  L8E 3C3

On 04.04.2015 02:32, James B. Byrne wrote:
> I am seeing log file entries like this:
> 
> IN=eth0 OUT=eth1 SRC=109.74.193.253 DST=x.y.z.34 LEN=122 TOS=0x00
> PREC=0x00 TTL=48 ID=49692 PROTO=ICMP TYPE=3 CODE=3 [SRC=x.y.z.34
> DST=109.74.193.253 LEN=94 TOS=0x00 PREC=0x00 TTL=53 ID=41330 PROTO=UDP
> SPT=34679 DPT=53 LEN=74 ]
> 
> This is found on our gateway host.  eth0 is the WAN i/f, eth1 is the
> LAN i/f.  Our netblock is x.y.z.0/24.  Can somebody tell me what this
> record is?
> 
> 
IN=eth0 OUT=eth1 SRC=109.74.193.253 DST=x.y.z.34 LEN=122 TOS=0x00
PREC=0x00 TTL=48 ID=49692 PROTO=ICMP TYPE=3 CODE=3

This is a "Port unreachable" message from host 109.74.193.253.

[SRC=x.y.z.34 DST=109.74.193.253 LEN=94 TOS=0x00 PREC=0x00 TTL=53
ID=41330 PROTO=UDP SPT=34679 DPT=53 LEN=74 ]

This is probably the cause of the above error: SRC=x.y.z.34 tried to do
a DNS lookup on DST=109.74.193.253 which failed (hence the icmp response).

Regards,
  Dennis