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3198 discussions

What records AMPR.ORG dns allow ?
by R P 11 May '17

11 May '17

Hi Someone know what currently the ampr.org DNS allow to enter ? I know of A and MX ... is there other ? (example SPF) ? Any Info Welcome .. Regards Ronen - 4Z4ZQ http://www.ronen.org Ronen Pinchooks (4Z4ZQ) WebSite<http://www.ronen.org/> www.ronen.org ronen.org (Ronen Pinchooks (4Z4ZQ) WebSite) is hosted by domainavenue.com

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Re: [44net] storm blocking
by Rob Janssen 11 May '17

11 May '17

> The second one > runs a wall display in the department, it shouldn't be probing anything. > It's a reassigned machine, so perhaps a previous user of that machine > was doing some research scanning too. Sorry about that. At the time I put it on the list it had the reverse DNS ipsecscanner.sysnet.ucsd.edu and that is what it was doing. I removed it now. A problem of my method of blocking is that I cannot keep stats of activity of the address, so addresses may remain on the list far too long. But again, there are enough other entries for "research" from several other US and German universities. It appears to be a popular way of annoying people. Of course the interesting thing about the UCSD ones was that the traffic came through the tunnel even though our network is BGP routed. Not sure if it is still like that, I believe you changed something there. Several scanners offer opt-out but I think the research is mainly to see what people do when removal is promised but not done or only very temporarily. For example, I contacted the shodan.io guy twice for removal from his scanner, both times he removed our network only to re-add it within days. He probably expects that you will check after he answered the mail, see it is gone, and then not pay attention to it so he can continue his abuse. Rob

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Re: [44net] storm blocking
by Rob Janssen 10 May '17

10 May '17

> The DDoS attack on net 44 continues. I'm filtering out a goodly amount > of it at amprgw, but the people whose subnets are directly connected (BGP > announced) are getting hit too, and there's nothing I can do to filter it > out here. Our traffic is not particularly high here, of course there is a few Mbit/s of noise but it has been higher at times. Rob

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storm blocking
by Brian Kantor 10 May '17

10 May '17

The DDoS attack on net 44 continues. I'm filtering out a goodly amount of it at amprgw, but the people whose subnets are directly connected (BGP announced) are getting hit too, and there's nothing I can do to filter it out here. Basically, if you're directly connected (ie, not on a tunnel), you have to add a list of bad guys to your own firewall blocking. Here is a little script that will create a list of candidate addresses for blocking. You'll need the 'badguys' program, which I'll post below. What this does is give you a list of addrsses that sent you more than 1000 packets in the sample period. If you're connected via tunnel, you probably don't need this. I run this several times a day to accumulate a list of bad guys. I sample 100 million packets at a time; smaller subnets will probably want to use a smaller sample size. This was developed on FreeBSD but I'm told it works fine on Linux Hope this helps. - Brian ----------------------------------------------------------- block.sh: #!/bin/sh # # generate a list of possible bad guys # # sample incoming traffic, 100,000,000 incoming packets # during DDoS storm on a /8, this takes about 3 minutes time tcpdump -w /tmp/t.pcap -s 40 -c 100000000 # turn into a list of source IP addresses with counts, # sorted by decreasing count # throw away all those counted less than 1000, # delete the count from the line # elide our own addresses (put your own in the egrep) # store in a file ./badguys /tmp/t.pcap \ | sort \ | uniq -c \ | sort -rn \ | sed -e '/^ /d' \ | sed -e 's/.* //' \ | egrep -v '^44\.|^169\.228\.' \ > /tmp/badguys # all done with this file rm -f /tmp/t.pcap exit 0 ----------------------------------------------------------- badguys.c: /* * reads pcap capture file (use tcpdump -w to create) named * * spins through it, listing the IP source address on stdout * prints summary statistics on stderr * * the documentation on the pcap library leaves a lot to be * desired, use the source. a lot of what you need is in tcpdump.c * * compile me with * cc -g -Wall badguys.c -lpcap -o badguys * * (You'll need to have libpcap installed) * * Brian Kantor, UCSD, 2017 */ /* probably most of these includes are superfluous */ #include <sys/errno.h> #include <sys/types.h> #include <ctype.h> #include <errno.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include <net/ethernet.h> #include <netinet/in.h> #include <netinet/in_systm.h> #include <netinet/ip.h> #include <arpa/inet.h> #include <pcap/pcap.h> #include <pcap/bpf.h> void getpkt(u_char *, const struct pcap_pkthdr *, const u_char *); char * iptoa(u_long); int capcount = 0; int skipcount = 0; int main(int argc, char**argv) { char inpcapname[FILENAME_MAX+1]; char errbuf[BUFSIZ]; pcap_t *pcap; int rslt; if (argc != 2) { fprintf(stderr, "Usage: %s pcapfilename\n", argv[0]); exit(1); } strncpy(inpcapname, argv[1], FILENAME_MAX); fprintf(stderr, "opening PCAP file %s\n", inpcapname); pcap = pcap_open_offline(inpcapname, errbuf); if (!pcap) { fprintf(stderr, "Error: %s\n", errbuf); exit(1); } /* * read through the capture savefile */ rslt = pcap_loop(pcap, 0, getpkt, 0); if (rslt) { fprintf(stderr, "pcap_loop returned %d\n", rslt); pcap_perror(pcap, "pcap_loop returned"); exit(1); } pcap_close(pcap); fprintf(stderr, "%d packets read from savefile\n", capcount); fprintf(stderr, "%d non-IP packets discarded\n", skipcount); exit(0); } /* * called by pcap_loop once per packet read from savefile */ void getpkt(u_char *user, const struct pcap_pkthdr *h, const u_char *p) { struct ip * ip; u_short * ethertype; capcount++; /* get the Ethernet packet type */ ethertype = (u_short *)&p[(2*ETHER_ADDR_LEN)]; /* we only want IP packets */ if (ntohs(*ethertype) != ETHERTYPE_IP) { skipcount++; return; } /* IP packet starts after Ethernet header */ ip = (struct ip *)&p[ETHER_HDR_LEN]; puts(iptoa(ntohl(ip->ip_src.s_addr))); return; } /* * nicely format host-byte-order u_int into dotted quad * returns pointer to a small static buffer; you can't * call this more than once in a single syslog or printf statement */ char * iptoa(u_long ipaddr) { static char buf[32]; snprintf(buf, sizeof buf, "%lu.%lu.%lu.%lu", (ipaddr >> 24) & 0xff, (ipaddr >> 16) & 0xff, (ipaddr >> 8) & 0xff, (ipaddr) & 0xff); return buf; }

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Re: [44net] iptables logging of IPIP
by Rob Janssen 10 May '17

10 May '17

> Perhaps then I didn't glean that data...but HOW does one 'decode' that > MAC then? > Meaning, how do I see SRC, DST protocol number, etc.? > (this might be helpful looking through kernel-mod ipt) That MAC is just a hexdump of the IP header so you extract the bytes you want and convert them to decimal. It should have been only 20 bytes but it is much longer, probably someone misunderstood the length field somewhere. Rob

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Re: [44net] iptables logging of IPIP
by Rob Janssen 10 May '17

10 May '17

> What [additional] information does this MAC field provide to you on the > tunnel? > Does this field change per packet? > Is there some documentation on how to decode it? > Is it a hashing of some sort, or just a hex copy of the data (IP header)? All these questions are answered in my initial post. It was useful, as it allowed to see what tunnel endpoint had sent a packet when it was dropped by the firewall on the tunl0 device itself. Of course the tunnel source can be seen on the eth0 device but there you cannot (or it is very difficult to) examine the encapsulated packet. Rob

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iptables logging of IPIP
by Rob Janssen 10 May '17

10 May '17

Today I noticed that the log on our gateway lost some detail for IPIP traffic. (now that everyone is discussing trouble with tunneled packets...) In the past with Linux kernel 3.2 and 3.16, when some packet incoming over tunl0 was hitting a LOG target in the iptables firewall, it would log a MAC address of the entire IP header as hex bytes (colon separated), like this: Apr 16 07:39:13 gw-44-137 kernel: [1266597.275238] Packet DROP: IN=tunl0 OUT=eth 1 MAC=45:00:00:44:10:f9:00:00:f9:04:e9:f9:54:6a:7e:b8:d5:de:1d:c2:45:00:00:30:64 :21:40:00:7e:06:29:1a:c0:a8:58:0a:2c:89:2a:51:e9:c0:14:66:1f:fa:64:c8:00:00:00:0 0:70:02:20:00:70:a9:00:00:02:04:05:b4:01:01:04:02:c8:78:03:6b:1a:74:bd:29:37:8d: da:27:61:d7:2f:22:b0:b5:2b:b8:b4:61:3a:60:08:23:48:1b:26:15:57:80:00:00:85:ec:03 :32:df:df:85:46:bb:b3:40:e4:0f:df:4b:3d:93:e0:ed:f3:46:d4:e0:17:68:b6:dd:5d:f1:3 f:1b:1e:6f:a0:f0:69:5c:28:4a:3c:24:17:20:ff:e5:97 SRC=192.168.88.10 DST=44.137.4 2.81 LEN=48 TOS=0x00 PREC=0x00 TTL=126 ID=25633 DF PROTO=TCP SPT=59840 DPT=5222 WINDOW=8192 RES=0x00 SYN URGP=0 (wrapped) Ok, that was much too long, there was probably a bug somewhere and the intention was to show only the outer IP header. Recently I switched to kernel 4.9 but now the packets are logged with no info at all: May 9 18:05:57 gw-44-137 kernel: [359091.001991] Packet DROP: IN=tunl0 OUT= MAC= SRC=192.168.15.2 DST=44.137.75.242 LEN=243 TOS=0x00 PREC=0x00 TTL=123 ID=39243 PROTO=UDP SPT=5198 DPT=5198 LEN=223 The MAC field is now simply empty. With the first format I had a small perl script that processed the log entries and showed the tunnel endpoint that was sending the packet: Apr 16 07:39:13 gw-44-137 kernel: [1266597.275238] Packet DROP: IN=tunl0 OUT=eth1 TUNL=84.106.126.184 SRC=192.168.88.10 DST=44.137.42.81 LEN=48 TOS=0x00 PREC=0x00 TTL=126 ID=25633 DF PROTO=TCP SPT=59840 DPT=5222 WINDOW=8192 RES=0x00 SYN URGP=0 However, now this is no longer possible. I have tried finding info about it but no success yet. Does anyone know if there is some parameter to tune this behaviour? Rob

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Re: [44net] iptables logging of IPIP
by Rob Janssen 10 May '17

10 May '17

> In the past with Linux kernel 3.2 and 3.16 > Recently I switched to kernel 4.9 That was incorrect. The first behaviour was with kernel 3.2 and the 3.16 kernel does not log that long MAC address anymore. The 4.9 kernel is on another system, it is not related to this. Rob

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gateway errors detail available
by Brian Kantor 09 May '17

09 May '17

If your gateway appears in the pkterrors.txt file, the packets which caused that error to be logged and the packet to be dropped are now available in a file you can retrieve with your web browser. They are binary log files, so you'll need a program to interpret them. The URL for a typical file is https://gw.ampr.org/private/errors/67.164.64.8.bin where of course the IP address part changes to whatever your gateway address is. The files are removed and start fresh at midnight Pacific time (GMT-7 or -8). For some error-prone sites, they get large-ish. The format of each file is /* * 2 bytes error number (unsigned short) * 2 bytes packet length (unsigned short) * 4 bytes time (seconds since epoch) * 4 bytes fractional seconds (microseconds) * n bytes (packetlen) encapped IP packet in network byte order */ I have a 'C' program that will interpret the file, which you may have if you're interested. It calls some library routines that you probably don't have, so you'll have to modify it to get it to run on your system. In particular, the error number and packet content interpreters are up to you. I don't think the compiled code will run on Linux but you're welcome to it if you have a FreeBSD system to run it on. Or if you like, I'll run it on your gateway error log file and mail you the output. That looks like this: timestamp (GMT) len err error -------------------- ---- ---- ---------- 2017-05-08T19:04:32Z 40 [19] dropped: non-44 inner source address ver=4 hl*4=20 tos=00 ip_len=40 id=d431 off=0000 ttl=244 proto=6 cksum=7d51 [TCP] 184.105.139.107:44864 -> 44.118.5.2:16992 2017-05-08T19:05:51Z 40 [19] dropped: non-44 inner source address ver=4 hl*4=20 tos=00 ip_len=40 id=18f4 off=0000 ttl=43 proto=6 cksum=5b02 [TCP] 181.23.53.75:58147 -> 44.118.5.2:2222 etc. So far, keeping these log files doesn't seem to burden the system very much. If that changes, I'll have to discontinue them. - Brian

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gateway and host bad packets report
by Brian Kantor 09 May '17

09 May '17

The amprgw router is now periodically preparing a report of the bad packets that it discards. You can retrieve a copy of this report right next to the statistics report: <https://gw.ampr.org/private/pkterrors.txt>. You'll need the same userid and password as for the stats.txt file (same as the one you use to fetch the encap file from the portal.) It's in gateway and source address order to make finding your own gateway and host in the listing somewhat easier. Current plan is to update the report every 15 minutes, and restart the tally at midnight Pacific time. Here are the first few lines (there are currently about 2,300). Let me know if you have any problems or questions with this. - Brian Last update at Wed May 3 15:45:00 2017 gateway inner src #errs indx error type ---------------- ---------------- ----- ---- ------------------------------- 2.84.96.101 44.154.0.1 9 [ 8] dropped: encap to encap 2.84.96.101 44.154.2.1 3 [ 8] dropped: encap to encap 2.84.96.101 44.154.3.1 3 [ 8] dropped: encap to encap 2.84.96.101 44.154.4.1 4 [ 8] dropped: encap to encap 2.84.96.101 44.165.2.3 106 [ 8] dropped: encap to encap 18.96.0.110 44.44.7.225 6 [ 8] dropped: encap to encap 18.96.0.110 44.44.7.232 8 [ 8] dropped: encap to encap 23.30.150.141 23.30.150.141 1326 [19] dropped: non-44 inner source address

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