grep multiple regex of a line - regex

Question

I want to log incoming syslog from my router to a file. I recieve the syslog with
nc -l -u -p 514 > syslog.log
The incoming lines are made of several fields that are separated by a whitespace.
Here are two complete sample lines from syslog:
<4>Nov 29 16:15:29 kernel: [ 3571.330000] DROP IN=vlan2 OUT= MAC=00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00 SRC=1.235.114.117 DST=1.52.79.209 LEN=337 TOS=0x00 PREC=0x00 TTL=115 ID=30831 PROTO=UDP SPT=161 DPT=220 LEN=317
<4>Nov 29 16:15:30 kernel: [ 3572.200000] DROP IN=vlan2 OUT= MAC=00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00 SRC=7.27.203.227 DST=122.2.79.209 LEN=64 TOS=0x00 PREC=0x00 TTL=52 ID=44018 DF PROTO=TCP SPT=5108 DPT=220 SEQ=3468909622 ACK=0 WIND
I want only the Time,SRC,PROTO,SPT,DPT fields in my logifile so I thought I could use something like this as a test for DST and SRC only:
nc -l -u -p 514 | egrep -o 'SRC=[0-9]{1,3}.[0-9]{1,3}.[0-9]{1,3}.[0-9]{1,3}|DST=[0-9]{1,3}.[0-9]{1,3}.[0-9]{1,3}.[0-9]{1,3}' > syslog.log
Unfortatly this prints every field in a new line like this:
SRC=1.235.114.117
DST=1.52.79.209
SRC=7.27.203.227
DST=122.2.79.209
I then want a output looking simmilar to this corresponding to the first line:
Time,SRC,PROTO,SPT,DPT
Nov 29 16:15:29,7.27.203.227,TCP,5108,220
There is another problem. Sometimes I receive lines that does not contain a "DS" field like in the second line of the samples. So counting fields with awk separators seems not to work since they are not consistent.
Anyone an idea how I can do this?

Answer 1

As #twalberg suggested I now use syslog-ng.
this is my syslog-ng.conf:
#version: 3.7
#include "scl.conf"
options {
threaded(yes);
chain_hostnames(no);
stats_freq(43200);
mark_freq(3600);
};
source s_udp { udp(port(514)); };
parser p_kv {kv-parser(prefix(".kv.")); };
destination d_router_file { file("/var/log/firewall_drops.csv" template("${DATE},${.kv.SRC}${.kv.PROTO},${.kv.SPT},${.kv.DPT}\n")); };
log { source(s_udp);parser(p_kv);destination(d_router_file); };