44net March 2020

44net@mailman.ampr.org

21 participants
29 discussions

Re: [44net] Portal/Wiki text
by Rob Janssen 26 Mar '20

26 Mar '20

> One minor thing to bring up though, since I went and re-read the text. It says > "ISPs don't configure their routers with publicly routable IP space for end users, why would you?" > This is by and large false. Some do indeed use 1918 space for customer facing interfaces, but most do not, as this practice this can break PMTUD due to dropping PTB messages sent by 1918 numbered interfaces and is not generally not recommended. It looks like this came from the HamWan people who apparently use a lot of RFC1918 addressing, I think at first even their whole network was on RFC1918 space and they introduced net44 capability only later. However, in our network here we exclusively use net44 addresses, also for links and routers. Of course we do have appropriate firewalls in place. The first line of defense is that at the internet router, all incoming traffic is blocked by default unless the destination is from an address list of only systems that provide services that are to be visible from internet. And in the last router before the actual system there is an additional firewall that opens only certain ports for everyone, and restricts management ports to another address list that has only addresses of known operators, or at most the country subnet. This makes the result similar to using RFC1918 addressing (which provides protection because it can only be routed locally), but without the disadvantages that you mention. Anyway, I am not that much concerned about that part of the text, it will depend on local policies and we do not use that method of subnet allocation anyway. My main concern at this time is that "outsiders" (not licensed radio amateurs) apparently find our network in their search for IPv4 address space, and make requests that we have to reject. This rejection often leads to discussion (partly because there is no terminate-this-request option in the portal, a coordinator can only accept it or send it back to the requester for more detail). Therefore I think it would be best when those outsiders immediately see that this system is not for them. Rob

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Re: [44net] Security - Nested IPIP
by lleachii＠aol.com 26 Mar '20

26 Mar '20

Rob, I now understand what you meant by this. I'm not seeing [lots of] improper Header 1 traffic with a known gateway IP as a SRC IP (and if I do, I want to block as it's asymmetric, as I tax AMPRGW on the reply trip). I receive the packet from AMPRGW (i.e. they're using the Public Internet instead of AMPRNet to reach the NTP server). * AMPR <> AMPR (OK, This allowed - as I list this service to my subnet in the Wiki) * Registered_Public <> Registered_Public (OK; but closed for MOST services) * Registered_Public <> AMPR (OK, not announced, taxes AMPRGW - may close soon; closed for some services) * Tunnel (Header 0) <> Public IP (Header 1) (NO - I consider this a crafted packet or improperly configured gateway, creates asymmetry; and taxes AMPRGW on the reply) - but cannot be mitigate except by blocking registered gateways on the de-encapsulated side of tunl0 I would advise you block that traffic with an improper Header 1 from registered gateways of you flag it via Header 0. But this discussion now causes me to recall discussions we've had before on: 1.) the security of seeing the Registered Public IP on both sides of the tunnel 2.) policy-based routing and the need to separate routing tables comes to mind....this comes from operators' failure to set that up. I'm now wondering how such a config is [incorrectly] made (i.e. the inside Header has the incorrect SRC)....likely because of no route policy...another discussion... Just note that bad IPENCAP is not the majority of bad traffic we're seeing on some nodes...in fact, bad IPENCAP is the least of this traffic (at least now). - KB3VWG Unfortunately this breaks legitimate traffic because some gateways are incorrectly configured (as I mentioned before) and send tunneled traffic with their own external address as source address, instead of the AMPRnet address assigned to the gateway. So such traffic is accepted as well here (i.e. traffic with a source address of one of the gateways)

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DNS procedures/process
by Elias Basse 26 Mar '20

26 Mar '20

Are there any updated dns procedures with regards to coordinators? I have a new coordination and haven’t done it in a while and can no longer find the email with the procedure for adding dns. At one point I thought this was in the portal. Best Regards Elias Kd5jfe Louisiana AMPR coordinator Sent from my iPhone

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Re: [44net] Portal/Wiki text
by Rob Janssen 26 Mar '20

26 Mar '20

> The relevant page has been updated with your suggested dialogue Thanks! It is at least an attempt, let's hope it works. Other coordinators beware: there is a hosting company owner from the Netherlands that is apparently shopping for a subnet. After I rejected him, he tried in Germany. Rob

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Re: [44net] Security - Nested IPIP
by Rob Janssen 25 Mar '20

25 Mar '20

> Please keep in mind though, the malicious traffic I observed did not originally come from AMPRGW. I originally observed the nested IPENCAP traffic from a Polish Public IP that's still currently registered as an AMPRNet gateway. As you know in later Linux kernels it became more difficult to see the outer header of the IPIP packet in a firewall rule handling the tunneled traffic. To circumvent that, a couple of years ago I added a rule to the firewall that sets a packet mark on traffic received from AMPRGW (matching the source IP in the outer header). This packet mark can then be checked in the firewall for the tunneled traffic. Source addresses outside AMPRnet are only accepted when the packet mark is set. Unfortunately this breaks legitimate traffic because some gateways are incorrectly configured (as I mentioned before) and send tunneled traffic with their own external address as source address, instead of the AMPRnet address assigned to the gateway. So such traffic is accepted as well here (i.e. traffic with a source address of one of the gateways) We really should abandon the IPIP tunnel mesh and move on to something a bit more secure (and easier to use on modern equipment)... Rob

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Re: [44net] Portal/Wiki text
by lleachii＠aol.com 25 Mar '20

25 Mar '20

Rob, The relevant page has been updated with your suggested dialogue: http://wiki.ampr.org/wiki/Requesting_a_block 73, - Lynwood KB3VWG

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Re: [44net] Security - Nested IPIP
by lleachii＠aol.com 25 Mar '20

25 Mar '20

David, 1. OpenWrt is Linux; and my previous gateway ran Ubuntu Linux (no *nos) - I cannot speak to other Routing Planes running IPENCAP tunnels. Also note machines running tnos have the machine's kernel and userland software to possibly interact with a packet. I only surmise without firewalls, some of the basic routing concepts apply to other Network Operating Systems too. 2. We're running AMPR gateways, so routing would be ON - I'm lost at the remark about IPv4 Forwarding = OFF. It seems as if you're suggesting to "disable routing on the router". I can only speak for Linux-based devices that are also performing functions as an actual router. Servers (i.e. with net.ipv4.ip_forward=0 and net.ipv6.ip_forward=0) merely receiving all of your IPENCAP packets should not apply here. Even when I originally ran a Linux server as my APMRNet device - downstream of my border router, I still had a /24 (253 other usable IPs) - so I've always had the need to route some IPs. You asked: Are these users trying to break into our AMPR hosts due to gaps in our firewalls or are they exploiting incomplete firewalls to use them as relay hosts to SOURCE attacks out on the Internet? Answer: Both are logically possible with an unfirewalled router or device and/or policy route isolation of the interfaces (in the case of a router). I described a scenario where a malicious actor can use the asymmetry of the routing to get a login screen (e.g. of your router or server) only accessible locally. It also seems as if DDoS is a consequence, or the modus operandi, of some traffic (e.g. TCP reflections cause 100% open connections at the router or a machine). 2b. These would be firewall rules to mitigate. 3. I have provided: tcpdump outputs and netflow records, the tcpdump command to observe the nested IPENCAP and a netflow log of a packet which (had it not been firewalled) could have double routed across my device - let me know what additional filters are needed. Also, the device running the dump must be your registered gateway (to which these actors are directing the traffic in this discussion), not a random device on the Internet. https://linux.die.net/man/8/tcpdump Nested IPENCAP: tcpdump -vvv -n -i tunl0 proto 4 I haven't thought of a tcpdump to observe all Header 1 routing - as the vice versa SRC/DST could be valid in some instances - this command only shows traffic entering or exiting tunl0 without your IP...it will also hit FALSELY on the RIP44 packets, hence the last part: tcpdump -vvv -n -i tunl0 src net not 44.60.44.0/24 and dst net not 44.60.44.0/24 and not host 224.0.0.9 4. I have posted the Second header scenario and it's remains available at the Wiki page. There should be no 3rd header scenario - that's the malicious activity the Second Header firewall rule blocks. http://wiki.ampr.org/wiki/Firewalls (and see previous emails on this topic) - FYI, there's nothing 44net-specific to the rules I suggested - # THIS PREVENTS NESTED IPENCAP (BCP 38) iptables -t raw -I PREROUTING -p 4 -i tunl0 -j DROP HTTP Rule (OpenWrt syntax - iptables-based): config rule option target 'ACCEPT' option proto 'tcp' option name 'AMPR_WWW' option family 'ipv4' option dest_ip '44.60.44.10' option dest_port '80' option src '*' option dest 'amprnet' option extra '-m limit --limit 25/minute --limit-burst 100 -j ACCEPT' Block first TCP packet not SYN (again, OpenWrt syntax - iptables-based): config rule option proto 'tcp' option name 'Block_In_Not_SYN' option src '*' option target 'DROP' option extra '! --syn -m conntrack --ctstate NEW' (Also the normal SYN Flood and INVALID rules). 5. Yes you can have DNS records and not receive traffic from AMPRGW - just block it and/or remove its route. Following the Wiki (for an Linux or OpenWrt setup), the only allowed traffic from anywhere by default are routes from AMPRGW, so long as the machine's default iptables rule is drop or reject. So it's alarming to hear inquiries like this. This will not stop the actual IPENCAPed packets from the Internet via AMPGW for the IPs in the DNS zone. Please keep in mind though, the malicious traffic I observed did not originally come from AMPRGW. I originally observed the nested IPENCAP traffic from a Polish Public IP that's still currently registered as an AMPRNet gateway. 73, - Lynwood KB3VWG

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Re: [44net] Security - Nested IPIP
by lleachii＠aol.com 24 Mar '20

24 Mar '20

All, I wanted to make 2 notes regarding: dynamic IP addresses and AMPR TCP-based services. * An operator mentioned that it may perhaps be malicious dynamic IPs (no longer used by the operators in question) that are sending this traffic...I also think the [malicious] experience "via RIP[44]" had not occurred was noted... Since my gateway is in fact dynamic and still seeing issues...wouldn't it be prudent for those operators that are monitoring AND FIREWALLING their gateways to identify the rogue gateways for removal and dropping? Because, if they're rogue operators...**we now understand how our routes are being leaked**...as they are successfully relocating my new Public IPs (even though I'm dropping routing traffic and IPs out of tunl0 that != my allocation). * All operators running TCP services should ensure they are not reflecting SYN-ACK packets and/or experiencing half-open connections on the router and server as a result. Firewalling new TCP connections CONNECTION_STATE not SYN (unless you expect such traffic) and burst rules help. In OpenWrt, such activity can be easily seen on the Overview Page upon login at "Active Connections" graphic. ** I suggest as an extreme measure for those who have not blocked IPENCAP on tunl0 only to operators in the past - to do so; and/or renumber their router interface(s) possessing AMPR IPs (the IP does not need a DNS record if it doesn't need access from AMPRGW/Public Internet). This mitigates the malicious actors' ability to perform nested routing on your device. ** It is now apparent that 2nd and 3rd headers need to be properly firewalled on all gateways running IPENCAP. Be vigilant. ** Please make sure no internal LAN devices were compromised (thru asymmetric traffic that may have allowed a malicious person access to LAN machines). ** Nested IPIP can be firewalled (i.e. Header 2 - the third header); but there is no known solution to receiving a packet with a malicious Header 1 (i.e the second header - which could be expected to reach any device on Earth with a Public IP). Properly firewalling and monitoring traffic that you allow into your 44network (with 44net IPs) is important. ** If anyone running a Linux-based router can WireShark/tcpdump and observe MAC addresses directly on their tunl0, please let me know. This is believed a hash of the 4 SRC/DST IPs of Headers 0 and 1 - which could be used to authenticate traffic from gateways that != AMPRGW. 19:39 UTC 23MAR2020: 269 11.96 KB zone_amprwan_dest_DROP all * * 0.0.0.0/0 0.0.0.0/0 - AMPR_DropLoop 844 76.12 KB zone_amprwan_dest_DROP all * * !44.60.44.0/24 0.0.0.0/0 - Drop-AMPR_OUT_InvalidSRC This is ~30 seconds of traffic of drops from my router to forwarding of invalid Header 1 receipts. The first rule is all traffic from you in which KB3VWG != DST IP; and hence you asked me to route it for you. (I only allow this by coordination). It should be 0. I should note the second rule includes drops from my AMPRLAN that != bogons - but should otherwise be 0 too (e.g. unfirewalled, the packets could forward to BGP 44 IPs that exist on an operator's routing table as "properly NATed traffic" from an allowed gateway). 73, - Lynwood KB3VWG

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Portal/Wiki text
by Rob Janssen 21 Mar '20

21 Mar '20

Can someone please add some explanatory text to the relevant portal and wiki pages that inform the visitor that AMPRNet is a closed network that is only accessible to licensed radio amateurs. I got another of those requests that come from people that are just after some free IP space and submit an allocation request through the portal using some "handle" like used on whois as their "callsign". They probably find us using some search and then land on portal.ampr.org, make an account and file an allocation request. When walking that route, there is no information at all about the target audience, all information is just geared towards "how to request IP space", which they do. In the latest case, when I rejected the request saying it is only for licensed amateurs the request was re-submitted with a callsign which is not assigned to the person making the request. He probable searched again to find what licensed radio amateurs are and found some callsign that he then added to the request. (not knowing that we can do reverse lookups on those) They should at least at some point encounter some text that explains them that this network is not for their hosting purposes. Rob

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Security - Nested IPIP
by lleachii＠aol.com 16 Mar '20

16 Mar '20

All, The following are RAW firewall hits indicating nested IPIP in IPIP packets. I run a firewall that only allows IPIP from all of you (and rules that only allows the AMPRGW routes and my destination IPs); but since this is a RAW rule - it implies nothing of any operator. I have not reviewed my Netflow records; but please be vigilant of this traffic. I warned of this issue in the "ancient" 44 mailing archives. Table: RawChain PREROUTING (Policy: ACCEPT, 94829408 Packets, 59.38 GB Traffic)Pkts. Traffic Target Prot. In Out Source Destination Options Comment32 2.37 KB DROP 4 tunl0 * 0.0.0.0/0 0.0.0.0/0 - - 73 ::and elbow bump::, - Lynwood KB3VWG

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44net March 2020