> 128MB is only 3% of 4GB. What would be the problem reserving that for a lookup table?
BTW, a nice trick for such tables is to do a mmap of /dev/zero with the proper size as a
starting point, then write only the entries that are nonzero.
That way the vast spaces that are only zeroes will not occupy physical memory, and when
they are read by the forwarding code they read back as zeroes.
Linux also has a "|MAP_ANONYMOUS" flag to obtain the same result, I don't know if BSD has that. |Rob
> Interesting concept. Someday if we have enough memory I may try it, but
> right now amprgw (an old machine) has only 4 GB of memory. It'd die swapping.
128MB is only 3% of 4GB. What would be the problem reserving that for a lookup table?
Rob
On Sun, Apr 30, 2017 at 5:31 AM, Marc <monsieurmarc(a)btinternet.com> wrote:
> Maybe we should start sharing block lists.
Marc,
HamWAN has a public blacklist system. Feel free to subscribe to it. It
does not publish a full list, but rather sends addresses one by one,
instantly*, as they are blocked.
*It takes about 1.5 seconds for report of a hack attempt to propagate
to our logging system, pass analysis, and be published to our edge
routers' firewall.
Here is the code behind the system (including a Mikrotik script you
can use to subscribe):
https://github.com/kd7lxl/blacklist-service
Anything blocked by the HamWAN network will be published here:
http://monitoring.hamwan.net/blacklist
If it seems like it's not responding, that's normal. It is an HTTP
longpoll service, so it will hang until there is data to be published,
then that data is sent immediately. This mechanism allows pushing data
(in this case, a blacklisted address) to a Mikrotik router without
having to store admin credentials of that router on the blacklist
system. Since it uses a standard protocol, it can be adapted for other
platforms.
Tom KD7LXL
As I've mentioned, I'm now logging statistics for the amprgw
router. I could make these available on a web site, but I'm
hesitant to do so without consensus from the community because
the per-gateway stats have the side effect of revealing what
subnet goes to what gateway, thus giving the bad guys more
insight into how the AMPRNet-Internet gateway works and what
hosts to impersonate to inject bad packets into the network.
A sample of the statistics file is below.
What do you folks think about making this available?
- Brian
started at Sat Apr 29 10:15:37 2017
snapshot at Sat Apr 29 10:45:00 2017
uptime: 0+00:29:23 (1763 seconds)
packets/bytes
---------/---------
121781/76089093 ipip encapped input
117631/73371842 forwarded out
0/0 no source gateway
467445/48802372 raw input
467434/48801678 encapped out
0/0 no destination gateway
2646/175516 encap to encap dropped
7692 discarded
0 TTL exceeded
0 ICMP sent
615 routes loaded (gateway counters cleared) 1486 seconds ago at Sat Apr 29 10:20:14 2017
entry subnet encap gateway outpkts outbytes inpkts inbytes
----- ------------------- ----- ---------------- --------- --------- --------- ---------
0 44.0.0.1/32 ipip 169.228.66.251 2 175 0 0
[etc]
The portal has apparently crashed. I have no way to remotely
restart it, so it'll probably be down all night until Chris
wakes up and can take a look at it.
- Brian
Recently I noticed people sending IGMP protocol packets to amprgw, which
discards them (as it does for all multicast destinations sent to it).
I don't think I'm going to write the necessary code to handle group
membership, so dropping the packet is probably the best thing to do.
Amprgw currently does NOT send 'destination unreachable' ICMP packets,
including 'protocol unreachable', because those should be rate limited
which makes coding the necessary response mechanism somewhat complicated.
(True, I could steal the necessary code from the FreeBSD kernel and
adapt it, but that's a lot of work. Maybe someday.) And I also don't
want to use up encap bandwidth sending ICMP back to the AMPR hosts.
The only ICMP that amprgw currently will originate is TIMXCEED when an
encapped packet's TTL reaches zero, so that 'traceroute' will work.
- Brian
> That is the Mirkotik discovery protocol indeed. I struggled with this too at first until I found that you can enable/disable it on select interfaces. By default it sends and listens on all interfaces. I'll post a small tutorial on where to find and disable it per interface when I arrive at work (unless someone beats me to it)
> I also firewalled in&outbound that on all but my internal interfaces just to be extra certain. I would recomend everyone doing so too unless you need it for some reason on an external interface.
> Like with Cisco's CDP or Juniper's LLDP, you normally don't need it on external interfaces.
Well, actually it would not be so bad to run this, and implement a receiver program on amprgw and other gateways.
It provides useful info about what is at the other end of the tunnel, including the IP address of the router,
software version, identity, etc.
When everyone would be running this, you would have an immediate overview about which tunnels are alive, etc.
A bit problematic could be that the router likely sends all packets at the same time and thus some 400 packets
are queued for output at once, clogging up the internet interface.
Rob
I've spent the last few hours adding some instrumentation
(various counters) to the ipip daemon. Here's a sample of
some of the data I now have available. This is a work in
progress.
The counters are packets/bytes.
- Brian
started at Thu Apr 27 22:51:19 2017
uptime: 0+00:08:41
15940/8895013 encapped input
13516/8414203 forwarded out
0/0 no source gateway
158252/9266766 raw input
159062/9316591 encapped out
0/0 no destination gateway
1613 discarded
0 ttlexceeded
614 routes (614 ipip, 0 udpip) loaded 521 seconds ago at Thu Apr 27 22:51:19 2017
Once a minute, at 8 seconds past the minute, gateway 77.138.34.39
sends an encapped UDP packet to the amprgw router that has a zero inner
source address and an all-ones inner destination address. The payload
length is 94 bytes and the source and destination ports are both 5678.
The periodicity suggests that it's some process that runs every minute
(out of crontab?) and takes about 8 seconds to complete.
There is a list of things port 5678 may be used for at
http://www.speedguide.net/port.php?port=5678
This may be Mikrotik Neighbor Discovery protocol.
Here's a log record of one such packet:
Apr 27 17:02:08 <local0.info> amprgw ipipd[22702]: ISRC0: len 122, os 77.138.34.39, od 169.228.66.251, is 0.0.0.0, id 255.255.255.255, ttl 64, proto 17
And here's a tcpdump of one:
17:06:08.419945 IP (tos 0x0, ttl 242, id 36314, offset 0, flags [none], proto IPIP (4), length 142)
77.138.34.39 > 169.228.66.251: IP (tos 0x0, ttl 64, id 0, offset 0, flags [none], proto UDP (17), length 122)
0.0.0.0.5678 > 255.255.255.255.5678: UDP, length 94
The portal record shows that this gateway belongs to Ronen Pinchuk [4Z4ZQ].
Ronen, when you have a few spare minutes, could you look at your gateway
and see if you can stop this from happening?
- Brian
This is my gateway. I'll shut it down until I can figure out what is
happening. I run FreeBSD and 44ripd, so that's why I am unusual.
Someone did indeed try a very aggressive portscan from a very diverse set
of hosts against me recently:
Apr 26 21:28:33 bbs kernel: Limiting closed port RST response from 402 to
200 packets/sec
Apr 26 21:31:45 bbs kernel: Limiting closed port RST response from 208 to
200 packets/sec
Apr 26 21:31:48 bbs kernel: Limiting closed port RST response from 395 to
200 packets/sec
-J
> On Apr 26, 2017, at 20:30, Brian Kantor <Brian(a)UCSD.Edu> wrote:
>
> A few times a minute, a host claiming to be ke6jjj-8 (44.4.39.8)
> is sending an encapped packet that is peculiar: it is either 40 or 44
> ...
