News items for tag time - Koos van den Hout

2020-07-01 A new home timeserver: GPS/RTC board 10 months ago
The Raspberry Pi GPS/RTC Expansion Board from uputronics came in today (thanks mailman!).

Next part needed: a gps antenna. But that's on backorder with another supplier.

Also needed: time to install raspbian on the Pi and start testing.

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2020-06-20 A new home timeserver: first parts, a Raspberry Pi 10 months ago
And yet another Raspberry Pi is showing up for my home network. This will become the GPS-based timeserver. I may add it to the NTP Pool when I'm satisfied enough with it.

It will probably also replace the 'shed' weather station computer in the long run, to save on power use.

I added an extra USB-based wifi adapter to the Pi. The shed has no wired network and my experience with the other computer there is that dual-band (2.4 GHz and 5 GHz) wifi support is the best way to have a chance to get working network.

I also ordered the Raspberry Pi GPS/RTC Expansion Board directly from uputronics.

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2020-06-15 A new home timeserver on order 11 months ago
After earlier tries to have a nice GPS-based timeserver for my home network I noticed a simple but very effective GPS 'hat' for the Raspberry Pi, the Raspberry Pi GPS Hat from Uputronix. While the Pi's are already taking over the home network just one more could be a nice addition. In the longer run this will probably replace the shed computer.

So I ordered a Pi with an added dual-band WiFi adapter, a case, the GPS hat and a GPS antenna. The GPS hat has PPS support so I will get the time correct. With the instructions from 5 minute guide to making a GPS Locked Stratum 1 NTP Server with a Raspberry Pi it should be easy. If this all works I may even add the resulting Pi to the IPv6 NTP Pool.

Update 2020-06-16: SOS Solutions came back with some bad news: the uputronix Pi GPS Hat isn't available anymore. I'm now looking at the comparable adafruit hardware which is somewhat more expensive, but offers the same options.

Update 2020-06-18: And the adafruit hardware is also not available soon. I cancelled the GPS unit part of the order and I'm looking at sourcing a GPS module for the Pi from another source. The GPS hat which sossolutions no longer sells is originally from uputronics where a newer version of the Raspberry Pi GPS/RTC Expansion Board is listed as available on the site. Based on a ublox chipset which allows me access to a lot of the GPS data.

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2019-11-13 Trying Suricata intrusion detection system (IDS) 1 year ago
After hearing about intrusion detection systems a few times I decided to give one a try at home. Although a lot of attacks are blocked I sometimes see weird attacks and it would be nice to have a better idea of what exactly the attack was.

Yes, I have weird interests sometimes. I'm glad I have an ISP (xs4all) where I can select the option 'give me the completely unfiltered Internet connection' so I even see SMB protocol attempts.

I first tried 'snort' but that doesn't deal with PPP interfaces by default. It can be recompiled to accept those but I did not want that. The next option I heard about is 'Suricata' which is running at the moment.

I was amused by the reports of DDoS-like NTP traffic. Those are caused by the NTP statistics gathering. I know NTP can be abused for generating DDoS traffic but all security reports about NTP servers I manage have been false positives.

Anyway it's running and complaining a lot about the traffic it sees. For example the IPv6 port scan/network mapping attempts I noticed two months ago are still active.
11/13/2019-15:06:59.703451  [**] [1:2002911:6] ET SCAN Potential VNC Scan 5900-5920 [**] [Classification: Attempted Information Leak] [Priority: 2] {TCP} 240e:00f7:4f01:000c:0000:0000:0000:0003:6050 -> 2001:0980:14ca:0001:020d:56ff:fece:ffe1:5901
11/13/2019-15:08:39.645780  [**] [1:2002911:6] ET SCAN Potential VNC Scan 5900-5920 [**] [Classification: Attempted Information Leak] [Priority: 2] {TCP} 240e:00f7:4f01:000c:0000:0000:0000:0003:5167 -> 2001:0980:14ca:0001:020d:56ff:fece:ffe6:5901

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2018-01-23 Avoiding the linux statefull firewall for some traffic 3 years ago
I was setting up a linux based firewall on a busy ntp server and to make sure everything worked as designed I added the usual:
iptables -A INPUT -j ACCEPT --protocol all -m state --state ESTABLISHED,RELATED
And after less than half an hour the system log started filling with
nf_conntrack: table full, dropping packet
nf_conntrack: table full, dropping packet
nf_conntrack: table full, dropping packet
nf_conntrack: table full, dropping packet
It is indeed a busy server. The solution is to exclude all the ntp traffic from the stateful firewall. Which means I have to allow all kinds of ntp traffic (outgoing and incoming) by itself.

The specific ruleset:
iptables -t raw -A PREROUTING --protocol udp --dport 123 -j NOTRACK
iptables -t raw -A OUTPUT --protocol udp --sport 123 -j NOTRACK

iptables -A INPUT -j ACCEPT --protocol udp --destination-port 123
I also made sure the rules for the ntp traffic are the first rules.

Traffic at this server is somewhat over 1000 ntp request per second. So the counters of the NOTRACK rules go fast.
# iptables -t raw -L -v
Chain PREROUTING (policy ACCEPT 1652K packets, 126M bytes)
 pkts bytes target     prot opt in     out     source               destination 
9635K  732M CT         udp  --  any    any     anywhere             anywhere             udp dpt:ntp NOTRACK
1650K  125M CT         udp  --  any    any     anywhere             anywhere             udp dpt:ntp NOTRACK

Chain OUTPUT (policy ACCEPT 1522K packets, 117M bytes)
 pkts bytes target     prot opt in     out     source               destination 
9029K  686M CT         udp  --  any    any     anywhere             anywhere             udp spt:ntp NOTRACK
1520K  116M CT         udp  --  any    any     anywhere             anywhere             udp spt:ntp NOTRACK
But no packets are dropped, which is good as this server is supposed to be under a constant DDoS.

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2018-01-19 Collecting ages of ntpd mode 7 probes 3 years ago
I noticed today one of the ntp servers I manage has been collecting ages of ntpd mode 7 probes without ever responding. But it makes a nice overview of probing IPv4 addresses:
remote address          port local address      count m ver rstr avgint  lstint
===============================================================================
184.105.139.82          1714 xxx.xxx.xxx.xxx        3 7 2      1 3413098   40058
184.105.139.72         14152 xxx.xxx.xxx.xxx        7 6 2      1 1107023   60553
185.165.29.145         33482 xxx.xxx.xxx.xxx        9 7 2      1 647886   73704
91.200.12.126          47493 xxx.xxx.xxx.xxx        2 7 2      1  12199   78678
185.94.111.1           33066 xxx.xxx.xxx.xxx       44 7 2      1 139771   83493
212.237.45.33          39353 xxx.xxx.xxx.xxx        1 7 2      1      0   84058
184.105.139.122        16124 xxx.xxx.xxx.xxx        4 7 2      1 1830407  127241
165.227.44.214         36749 xxx.xxx.xxx.xxx        1 7 2      1      0  138342
185.82.203.150         38141 xxx.xxx.xxx.xxx       12 7 2      1 147806  143793
185.2.81.90            33119 xxx.xxx.xxx.xxx        6 7 2      1 199742  180842
184.105.139.110        57630 xxx.xxx.xxx.xxx        6 7 2      1 968029  223794
77.87.79.97            34540 xxx.xxx.xxx.xxx        2 7 2      1  31910  251316
184.105.139.102        50130 xxx.xxx.xxx.xxx        3 7 2      1 2950157  308291
185.55.218.227         33716 xxx.xxx.xxx.xxx        2 7 2      1 853413  311971
104.243.41.54          30820 xxx.xxx.xxx.xxx        2 7 2      1 3258925  334017
123.249.27.176         35963 xxx.xxx.xxx.xxx        7 7 2      1 452131  339518
191.96.249.173         42895 xxx.xxx.xxx.xxx       10 7 2      1 692139  348753
71.194.80.50           51096 xxx.xxx.xxx.xxx        2 7 2      1  74579  392665
184.105.139.126        38393 xxx.xxx.xxx.xxx        2 7 2      1 3535530  394349
185.55.218.250         48871 xxx.xxx.xxx.xxx        2 7 2      1 537671  411921
184.105.139.86         34651 xxx.xxx.xxx.xxx        5 7 2      1 1361673  478157
123.249.24.175         37973 xxx.xxx.xxx.xxx        6 7 2      1 476469  502270
184.105.139.98         21269 xxx.xxx.xxx.xxx       10 7 2      1 718112  567076
184.105.139.70         38190 xxx.xxx.xxx.xxx        6 7 2      1 1107237  649625
66.55.135.62           54536 xxx.xxx.xxx.xxx        8 7 2      1  40836  721372
138.197.130.148        39857 xxx.xxx.xxx.xxx        2 7 2      1 415601  788308
191.96.249.113         36079 xxx.xxx.xxx.xxx        2 7 2      1 1501700  862267
184.105.139.78         37702 xxx.xxx.xxx.xxx        4 7 2      1 1637431  908028
159.89.47.224          47766 xxx.xxx.xxx.xxx        5 7 2      1 361160  913255
162.209.168.12         39122 xxx.xxx.xxx.xxx        2 7 2      1 109901  976174
123.249.26.159         34990 xxx.xxx.xxx.xxx       41 7 2      1  88999 1045070
184.105.139.74         38666 xxx.xxx.xxx.xxx        6 7 2      1 822261 1079624
185.55.218.242         54815 xxx.xxx.xxx.xxx        7 7 2      1  89032 1102095
191.96.249.12          48406 xxx.xxx.xxx.xxx        4 7 2      1 1133779 1198815
101.100.146.139        39660 xxx.xxx.xxx.xxx        3 7 2      1 1951322 1244586
209.250.238.186        39459 xxx.xxx.xxx.xxx        2 7 2      1  53072 1252190
119.1.109.85           51099 xxx.xxx.xxx.xxx       10 7 2      1 223881 1325320
184.105.139.118        34319 xxx.xxx.xxx.xxx        4 7 2      1 905995 1339133
184.105.139.106        15081 xxx.xxx.xxx.xxx        2 7 2      1 2932231 1430316
191.96.249.131         35972 xxx.xxx.xxx.xxx        2 7 2      1 1499287 1491171
185.55.218.237         43409 xxx.xxx.xxx.xxx        2 7 2      1 4255207 1497992
185.55.218.236         55927 xxx.xxx.xxx.xxx        3 7 2      1 1566148 1718947
138.68.247.41          41914 xxx.xxx.xxx.xxx        2 7 2      1  53524 1936953
184.105.139.94         41523 xxx.xxx.xxx.xxx        5 7 2      1 1112720 1948506
45.63.27.150           40862 xxx.xxx.xxx.xxx        2 7 2      1 1676933 1991259
185.188.207.13         45915 xxx.xxx.xxx.xxx       20 7 2      1 156321 2041538
185.44.107.183         45785 xxx.xxx.xxx.xxx        2 7 2      1 132706 2107890
184.105.139.90         35315 xxx.xxx.xxx.xxx        5 7 2      1 350936 2206670
191.96.249.61          30296 xxx.xxx.xxx.xxx        3 7 2      1  59063 2226284
195.22.127.173         40060 xxx.xxx.xxx.xxx        2 7 2      1  20615 2253429
184.105.139.114        56609 xxx.xxx.xxx.xxx        4 7 2      1 604491 2291452
104.243.41.52            123 xxx.xxx.xxx.xxx        2 7 2      1  85831 2381504
103.9.78.129           50367 xxx.xxx.xxx.xxx        2 7 2      1 868629 2449128
167.88.15.18           40815 xxx.xxx.xxx.xxx        2 7 2      1 182471 2525650
167.88.180.82          40640 xxx.xxx.xxx.xxx        2 7 2      1  66892 2715823
192.158.229.240        39284 xxx.xxx.xxx.xxx        4 7 2      1 163873 2759391
51.15.45.102           45371 xxx.xxx.xxx.xxx        2 7 2      1  92720 2768083
185.198.58.55          18637 xxx.xxx.xxx.xxx        2 7 0      1 802096 2787683
123.249.24.197         40362 xxx.xxx.xxx.xxx       37 7 2      1  85431 2983252
167.88.180.26          49125 xxx.xxx.xxx.xxx        4 7 2      1  60114 3023906
188.213.49.83          34969 xxx.xxx.xxx.xxx        2 7 2      1 254056 3095396
45.76.24.165           41025 xxx.xxx.xxx.xxx        2 7 2      1 107397 3103557
213.183.54.46          40409 xxx.xxx.xxx.xxx        5 7 2      1 206100 3224158
145.239.237.23         35814 xxx.xxx.xxx.xxx        2 7 2      1 571497 3264230
165.227.220.24         39557 xxx.xxx.xxx.xxx        2 7 2      1  52796 3292818
123.249.35.214         47756 xxx.xxx.xxx.xxx        2 7 2      1 242695 3296347
123.249.76.52          59698 xxx.xxx.xxx.xxx        8 7 2      1 246226 3446607
123.249.79.178         52301 xxx.xxx.xxx.xxx        2 7 2      1 839605 3455884
207.254.182.131        52337 xxx.xxx.xxx.xxx        4 7 2      1   1384 3648002
185.55.218.109         37602 xxx.xxx.xxx.xxx        2 7 2      1 752428 3652434
128.14.61.111          53586 xxx.xxx.xxx.xxx        3 7 2      1 103699 3796467
104.238.146.66         52224 xxx.xxx.xxx.xxx        2 7 2      1 138668 3837468
95.215.62.72           42111 xxx.xxx.xxx.xxx        4 7 2      1 608618 3932262
45.76.195.157          59987 xxx.xxx.xxx.xxx        2 7 2      1 143642 4096101
123.249.79.232         40165 xxx.xxx.xxx.xxx        4 7 2      1 146715 4317577
86.105.9.86            55857 xxx.xxx.xxx.xxx        4 7 2      1 115972 4329305
217.147.89.197         49717 xxx.xxx.xxx.xxx        4 7 2      1 314874 4463013
182.18.22.246          58611 xxx.xxx.xxx.xxx        3 7 2      1 359548 4485937
185.82.203.107         56661 xxx.xxx.xxx.xxx        7 7 2      1 176060 4516810
79.124.60.148          58043 xxx.xxx.xxx.xxx        2 7 2      1 687406 4684505
185.107.94.66          46254 xxx.xxx.xxx.xxx        2 7 2      1 1263073 4750583
191.96.249.84          49259 xxx.xxx.xxx.xxx        2 7 2      1 329846 5160890
111.121.193.201         6065 xxx.xxx.xxx.xxx        3 7 0      1 101832 5558503
185.188.207.15         33999 xxx.xxx.xxx.xxx        3 7 2      1  90416 5655119
185.117.74.118         52973 xxx.xxx.xxx.xxx        2 7 2      1   2174 5717159
185.82.203.58          59170 xxx.xxx.xxx.xxx        2 7 2      1  47838 5847404
185.162.128.66         39141 xxx.xxx.xxx.xxx        2 7 2      1   4837 5895126
All IP addresses with only 1 packet removed.

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2017-01-01 Leaped into 2017! 4 years ago
Jan  1 00:59:59 greenblatt kernel: [2538111.748198] Clock: inserting leap second 23:59:60 UTC
I usually distribute the leap second file to all servers I control to make sure there are no strange problems around it.

I wish everyone a good 2017!

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2016-03-31 Interesting report from pskreporter 5 years ago
PSKreporter negative time Interesting report from pskreporter psk map today: a negative time at which the signal was reported. I guess the reported time is taken from the original spotter, I had EB4DDQ in the log at 18:12 UTC, he had me in the log at 19:12 UTC.

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2016-01-28 Shodan using the IPv6 ntp pool to find active IPv6 addresses 5 years ago
Recently posted: shodan.io actively infiltrating ntp.org IPv6 pools for scanning purposes. So I tried:
ntpdate -d -u 2a03:b0c0:3:d0::18:b001
And indeed:
Jan 28 14:42:25 server kernel: [1187976.106758] FW reject: IN=ppp0 OUT= MAC= SRC=2604:a880:0800:0010:0000:0000:00fe:d001 DST=xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx LEN=60 TC=0 HOPLIMIT=55 FLOWLBL=0 PROTO=TCP SPT=49717 DPT=55554 WINDOW=54358 RES=0x00 SYN URGP=0 
Jan 28 14:42:25 server kernel: [1187976.107191] FW reject: IN=ppp0 OUT= MAC= SRC=2604:a880:0800:0010:0000:0000:00fe:d001 DST=xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx LEN=60 TC=0 HOPLIMIT=55 FLOWLBL=0 PROTO=TCP SPT=34680 DPT=50070 WINDOW=26315 RES=0x00 SYN URGP=0 
Jan 28 14:42:25 server kernel: [1187976.107256] FW reject: IN=ppp0 OUT= MAC= SRC=2604:a880:0800:0010:0000:0000:00fe:d001 DST=xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx LEN=60 TC=0 HOPLIMIT=55 FLOWLBL=0 PROTO=TCP SPT=49717 DPT=32764 WINDOW=15398 RES=0x00 SYN URGP=0 
Jan 28 14:42:25 server kernel: [1187976.107309] FW reject: IN=ppp0 OUT= MAC= SRC=2604:a880:0800:0010:0000:0000:00fe:d001 DST=xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx LEN=60 TC=0 HOPLIMIT=55 FLOWLBL=0 PROTO=TCP SPT=41249 DPT=44818 WINDOW=15146 RES=0x00 SYN URGP=0 
Jan 28 14:42:25 server kernel: [1187976.107380] FW dropped: IN=ppp0 OUT= MAC= SRC=2604:a880:0800:0010:0000:0000:00fe:d001 DST=xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx LEN=52 TC=0 HOPLIMIT=55 FLOWLBL=0 PROTO=UDP SPT=13864 DPT=30718 LEN=12 
Jan 28 14:42:25 server kernel: [1187976.107427] FW reject: IN=ppp0 OUT= MAC= SRC=2604:a880:0800:0010:0000:0000:00fe:d001 DST=xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx LEN=60 TC=0 HOPLIMIT=55 FLOWLBL=0 PROTO=TCP SPT=59140 DPT=25565 WINDOW=53087 RES=0x00 SYN URGP=0 
Jan 28 14:42:25 server kernel: [1187976.108613] FW dropped: IN=ppp0 OUT= MAC= SRC=2604:a880:0800:0010:0000:0000:00fe:d001 DST=xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx LEN=55 TC=0 HOPLIMIT=55 FLOWLBL=0 PROTO=UDP SPT=32950 DPT=8888 LEN=15 
Jan 28 14:42:25 server kernel: [1187976.110197] FW dropped: IN=ppp0 OUT= MAC= SRC=2604:a880:0800:0010:0000:0000:00fe:d001 DST=xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx LEN=60 TC=0 HOPLIMIT=55 FLOWLBL=0 PROTO=UDP SPT=39721 DPT=64738 LEN=20 
Jan 28 14:42:25 server kernel: [1187976.110315] FW dropped: IN=ppp0 OUT= MAC= SRC=2604:a880:0800:0010:0000:0000:00fe:d001 DST=xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx LEN=50 TC=0 HOPLIMIT=55 FLOWLBL=0 PROTO=UDP SPT=46499 DPT=5632 LEN=10 
Jan 28 14:42:25 server kernel: [1187976.110405] FW dropped: IN=ppp0 OUT= MAC= SRC=2604:a880:0800:0010:0000:0000:00fe:d001 DST=xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx LEN=65 TC=0 HOPLIMIT=55 FLOWLBL=0 PROTO=UDP SPT=21934 DPT=47808 LEN=25 
Jan 28 14:42:31 server kernel: [1187981.938880] FW reject: IN=ppp0 OUT= MAC= SRC=2604:a880:0800:0010:0000:0000:00fe:d001 DST=xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx LEN=60 TC=0 HOPLIMIT=55 FLOWLBL=0 PROTO=TCP SPT=34235 DPT=993 WINDOW=0 RES=0x00 RST URGP=0 
Jan 28 14:42:31 server kernel: [1187982.030058] FW reject: IN=ppp0 OUT= MAC= SRC=2604:a880:0800:0010:0000:0000:00fe:d001 DST=xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx LEN=60 TC=0 HOPLIMIT=55 FLOWLBL=0 PROTO=TCP SPT=34235 DPT=993 WINDOW=0 RES=0x00 RST URGP=0 
Jan 28 14:42:31 server kernel: [1187982.197203] FW reject: IN=ppp0 OUT= MAC= SRC=2604:a880:0800:0010:0000:0000:00fe:d001 DST=xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx LEN=60 TC=0 HOPLIMIT=55 FLOWLBL=0 PROTO=TCP SPT=34237 DPT=993 WINDOW=0 RES=0x00 RST URGP=0 
Jan 28 14:42:33 server kernel: [1187984.398977] FW reject: IN=ppp0 OUT= MAC= SRC=2604:a880:0800:0010:0000:0000:00fe:d001 DST=xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx LEN=60 TC=0 HOPLIMIT=55 FLOWLBL=0 PROTO=TCP SPT=34245 DPT=993 WINDOW=0 RES=0x00 RST URGP=0 
Jan 28 14:42:34 server kernel: [1187984.620836] FW reject: IN=ppp0 OUT= MAC= SRC=2604:a880:0800:0010:0000:0000:00fe:d001 DST=xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx LEN=60 TC=0 HOPLIMIT=55 FLOWLBL=0 PROTO=TCP SPT=34244 DPT=993 WINDOW=0 RES=0x00 RST URGP=0 
I would have expected more ports tested.

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2015-07-01 And the leap second leaped fine 5 years ago
The world did not fall apart at the leap second...
Jul  1 01:59:59 greenblatt kernel: [5562265.176016] Clock: inserting leap second 23:59:60 UTC
Jul  1 01:37:53 ritchie ntpd[14950]: local_clock: ntp_loopfilter.c line 688: kernel reports positive leap second warning state
Jul  1 01:59:59 ritchie kernel: [5807507.207473] Clock: inserting leap second 23:59:60 UTC
Jul  1 02:13:11 ritchie ntpd[14950]: local_clock: ntp_loopfilter.c line 688: kernel reports leap second has occured

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IPv6 check

Running test...
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