> iptables -I FORWARD ! -s 44.0.0.0/8 -i tunl0 -j DROP
> iptables -I INPUT ! -s 44.0.0.0/8 -i tunl0 -j DROP
> "If the source address of packets entering tunl0 doesn't equal AMPRNet,
> DROP them."
The problem with that is that it will also drop the legitimate internet traffic that
is coming in via the gateway. So, when you want connectivity to/from internet, it has
to be more complicated than that. You will need to put a rule in the mangle table for
protocol 4 traffic arriving from the gateway, and add some packet mark to the packet,
then in the above rule you exclude the packets with that mark.
Like this:
iptables -t mangle -A PREROUTING -p 4 -s 169.228.66.251 -j MARK --set-mark 1
and in the above rules add before the -j:
-m mark ! --mark 1
When you are inside a BGP routed subnet that also is on the tunnel mesh (like 44.137.0.0/16)
you will have to change the 169.228.66.251 to the address of your local gateway.
And of course, now you make yourself vulnerable again for dedicated attacks that spoof the
address of the gateway to send tunneled packets. So it remains mandatory to treat the
traffic received via the tunnels as hostile from-internet traffic!
Rob
> What's peculiar about a lot of these non-44 is that they have
> the encapsulated (inner) source and destination apparently interchanged:
> Apr 19 21:28:27 <local0.debug> amprgw ipipd[66472]: NON44: len 40,
> os 91.121.90.186, od 169.228.66.251, is 91.223.133.13, id 44.134.209.15,
> ttl 237, proto 6
> Either that or they're encapping in the wrong direction.
> I can't offhand think of what would cause THAT.
When I see odd addresses on encap links they often are ICMP packets (e.g. TTL exceeded, a result of traceroute)
that are sent by encap systems themselves and have the wrong source address.
Also, there appears to be some traffic in the noise of Internet that is completely ridiculous. Things like this:
Apr 20 10:43:30 Packet DROP: IN=eth0 OUT=gre14 SRC=44.137.49.139 DST=44.137.49.139 LEN=56 TOS=0x00 PREC=0x00 TTL=245 ID=35377 DF PROTO=ICMP TYPE=11 CODE=0 [SRC=44.137.49.139 DST=80.92.136.89 LEN=69 TOS=0x00 PREC=0x00 TTL=1 ID=35377 DF PROTO=UDP SPT=34973 DPT=53 LEN=49 ]
Note that 44.137.49.139 is not a registered AMPRnet address so it can never have sent this query, but
there is a ICMP TTL exceeded with source and destination being that address about a query it has allegedly
sent to 80.92.136.89, an address at some broadband provider that often re-occurs in this (amongst others).
It is completely unclear to me whether this is part of some attack on 80.92.136.89, on us, or is due to some
bug in a router (that sends ICMP with the wrong source address).
W.r.t. tunnel traffic, it sure is a good idea to drop anything not-AMPRnet.
I also see a lot of RFC1918 addresses in those packets, and even when I mail the
gateway operator about them I usually get a mail back that they are going to do something about
it, but that rarely happens (i.e. it just continues). E.g. this repeat offender:
Apr 20 07:52:05 Packet DROP: IN=tunl0 OUT=gre3 TUNL=90.63.239.151 SRC=192.168.1.3 DST=44.137.41.178 LEN=52 TOS=0x18 PREC=0xA0 TTL=59 ID=16343 DF PROTO=UDP SPT=50001 DPT=50000 LEN=32
It is unfortunate that setups of a gateway system can vary so widely that it
is impossible to give a good firewall example that will work for everyone.
My feeling is that many of the gateway operators lack the network knowledge to
get the firewall setup correctly, and it would be nice if we could educate them.
However, I am not going to be the sysop for even more systems. Some generic help
would be a good thing, but it is hard to do.
Rob
OK, it's my understanding the source and destination ports are undefined.
I'll just leave the mesh DOWN at this time, as the cross compiler is
configured exactly as before, and I am able to compile other software.
Thanks,
-Lynwood
KB3VWG
I've made a few small changes to the ipip encap firewall in
the UCSD encapsulating router. If something has stopped working
today because of that, please let me know.
- Brian
Hi all,
As part of my gateway setup I am looking to get rid of my BT Home hub (which I am having to use with DMZ turned on) and put in an inexpensive but more capable router.
So I was looking for peoples thoughts on either Microtik or Ubiquiti Edge routers. Is either particularly better suited?
Kind Regards Marc (2W0PNT)
> An update - I had success using compiling using 'cpp' instead of 'gcc'
cpp is not a compiler. it will only resolve your #include #define etc but the output is still C.
> I now receive less error output, but there's still an error:
Your crosscompiler setup is seriously broken! It apparently misses critical include file contents,
the first error about IPPORT_ROUTESERVER was also caused by that.
Maybe you missed some step in setting it up, I remember from the past where I tried this for my
Dreambox that it is quite an involved procedure.
Rob
All,
I've been able to successfully compile ampr-ripd for the native OS (Ubuntu Linux x64); but I receive errors when trying to compile for MIPS:
--------------------------------------------------------------------------
user@ubuntu-comp:~/ampr-ripd-1.16.2$ make CC=mips-openwrt-linux-musl-gcc LD=mips-openwrt-linux-musl-ld
mips-openwrt-linux-musl-gcc -Wall -O2 -o ampr-ripd ampr-ripd.c
ampr-ripd.c: In function 'create_fwsd':
ampr-ripd.c:1536:23: error: 'IPPORT_ROUTESERVER' undeclared (first use in this function)
sin.sin_port = htons(IPPORT_ROUTESERVER);
^
ampr-ripd.c:1536:23: note: each undeclared identifier is reported only once for each function it appears in
ampr-ripd.c: In function 'on_alarm':
ampr-ripd.c:1629:27: error: 'IPPORT_ROUTESERVER' undeclared (first use in this function)
sin.sin_port = htons(IPPORT_ROUTESERVER);
^
ampr-ripd.c: In function 'main':
ampr-ripd.c:1864:13: error: 'struct udphdr' has no member named 'dest'
(udh->dest == htons(IPPORT_ROUTESERVER)) &&
^
ampr-ripd.c:1864:29: error: 'IPPORT_ROUTESERVER' undeclared (first use in this function)
(udh->dest == htons(IPPORT_ROUTESERVER)) &&
^
ampr-ripd.c:1865:13: error: 'struct udphdr' has no member named 'source'
(udh->source == htons(IPPORT_ROUTESERVER)))
^
Makefile:30: recipe for target 'ampr-ripd' failed
make: *** [ampr-ripd] Error 1
--------------------------------------------------------------------------
Any assistance is appreciated
73,
KB3VWG
> I've been able to successfully compile ampr-ripd for the native OS (Ubuntu Linux x64); but I receive errors when trying to compile for MIPS:
IPPORT_ROUTESERVER should be defined in <netinet/in.h>
When it isn't, you can work around that by inserting this line near the top of the ampr-ripd.c file near the other #define lines:
#define IPPORT_ROUTESERVER 520
Rob
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--
73 and ciao, gus i0ojj
A proud member of linux team
Non multa, sed multum
