[lvs-users] DR-TUN Issues: Packets become martians on real server

Timothy R. Weiand timothy.weiand at gmail.com
Thu Dec 7 21:19:21 GMT 2017


So, it turns out that I am currently interviewing to find a new employer. I
will probably not pick this back up again; I will not be able to see if
this works in the “broken” environment.

Thanks for the help!
-Timothy
On Tue, Nov 7, 2017 at 12:38 PM Andrew Smalley <asmalley at loadbalancer.org>
wrote:

> Hello Timothy
>
> Aaron has told me that you are in AWS and this being the case I hope
> ipip does indeed work with my hints.
>
> It is worth noting that I know in AWS we can not do Layer4 DR however
> with the help of OpenVSwitch I know 100% that its possible to do
> Layer4 DR to any real server connected with either a VXLAN or GRE
> tunnel .
>
> I have personally done this in my private service and stretched a
> VXLAN from AWS to my private lab and other remote datacenters where my
> real servers reside.
>
>
>
>
> Andruw Smalley
>
> Loadbalancer.org Ltd.
>
> www.loadbalancer.org
> +1 888 867 9504 / +44 (0)330 380 1064
> asmalley at loadbalancer.org
>
> Leave a Review | Deployment Guides | Blog
>
>
> On 7 November 2017 at 16:51, Timothy R. Weiand <timothy.weiand at gmail.com>
> wrote:
> > Ooohhhh!! Let me try this.
> >
> > Thanks for the directions,
> > -Timothy
> > On Mon, Nov 6, 2017 at 1:55 PM Andrew Smalley <asmalley at loadbalancer.org
> >
> > wrote:
> >
> >> Hi Timothy,
> >>
> >> I've been testing ipip (Tun mode) and I have it working,
> >>
> >> I note that the Weak ES Model needs to be accounted for and the tunl0
> >> should be a /32 not a /24 as you have it on the real server.
> >>
> >> ip addr add 192.168.200.11/24 brd 192.168.200.11 dev tunl1
> >>
> >> becomes
> >>
> >> ip addr add dev tunl1 192.168.200.11/32 brd 192.168.200.11 dev tunl1
> >>
> >>
> >> I also have this in my /etc/sysctl.conf
> >>
> >> net.ipv4.conf.all.arp_ignore=1
> >> net.ipv4.conf.eth0.arp_ignore=1
> >> net.ipv4.conf.tunl1.arp_ignore=1
> >> net.ipv4.conf.all.arp_announce=2
> >> net.ipv4.conf.eth0.arp_announce=2
> >> net.ipv4.conf.tunl1.arp_announce=2
> >>
> >> net.ipv4.conf.all.log_martians=1
> >> net.ipv4.conf.default.log_martians=1
> >>
> >> And I ran this script portion to enable forwarding and disable the
> >> rp_filter
> >>
> >> if [ $1 = "tunl1" ]; then
> >>         echo 1 > /proc/sys/net/ipv4/conf/tunl0/forwarding
> >>         echo 0 > /proc/sys/net/ipv4/conf/tunl0/rp_filter
> >> fi
> >>
> >>
> >> This is with a 4.4.49 Kernel
> >>
> >> I hope this help you
> >>
> >>
> >> Andruw Smalley
> >>
> >> Loadbalancer.org Ltd.
> >>
> >> www.loadbalancer.org
> >> +1 888 867 9504 / +44 (0)330 380 1064
> >> asmalley at loadbalancer.org
> >>
> >> Leave a Review | Deployment Guides | Blog
> >>
> >>
> >> On 22 August 2017 at 12:43, Timothy R. Weiand <timothy.weiand at gmail.com
> >
> >> wrote:
> >> >
> >> > Aaron:
> >> >
> >> > I was able to get LVS-TUN working in between subnets in AWS if the
> real
> >> > server is a 3.x kernel (RHEL to be specific). I had to set the
> >> destination
> >> > side of the tunnel and the address on that interface to the VIP.
> Then, I
> >> > configured unbound to listen for the VIP address.
> >> >
> >> > We are working with RedHat to get the 4.x kernels fixed. But, no
> >> timeframe
> >> > on that fix.
> >> >
> >> > FYI - We are going to work towards open sourcing our work so that
> >> everyone
> >> > can see exactly what we have done.
> >> >
> >> > -Timothy
> >> >
> >> > On Thu, Aug 17, 2017 at 10:56 AM Aaron West <aaron at loadbalancer.org>
> >> wrote:
> >> >
> >> > > Hi Timothy,
> >> > >
> >> > > What you had working was it in AWS or VMWare?
> >> > >
> >> > > I've pretty much given up trying to get the spoofed reply traffic
> back
> >> > > out of AWS it gets dropped always with either DR mode or TUN unless
> I
> >> > > send it back via the director and that case I may as well do NAT
> mode
> >> > > instead...
> >> > >
> >> > > My understanding is that when egress traffic hits their edge they
> >> > > check the source matches the instance it came from and if it doesn't
> >> > > the packet gets dropped. However, all works fine if the client is in
> >> > > the same VPC so it doesn't need to go out past the edge of the VPC.
> >> > >
> >> > > Just interested if you found the same in your testing?
> >> > > Aaron West
> >> > >
> >> > > Loadbalancer.org
> >> > >
> >> > > www.loadbalancer.org
> >> > > +1 888 867 9504 / +44 (0)330 380 1064
> >> > > aaron at loadbalancer.org
> >> > >
> >> > > LEAVE A REVIEW | DEPLOYMENT GUIDES | BLOG
> >> > >
> >> > >
> >> > > On 10 August 2017 at 18:08, Timothy R. Weiand <
> >> timothy.weiand at gmail.com>
> >> > > wrote:
> >> > > > Julian:
> >> > > >
> >> > > > Good news and bad news: this guidance helped me get LVS-TUN
> working
> >> with
> >> > > a
> >> > > > 3.10.0 kernel. But, I am not able to use the same configuration to
> >> get
> >> > > > 4.4.x,4.8.x or 4.12.x working. We are working on doing further
> >> analysis
> >> > > to
> >> > > > ensure it is kernel dependent and not distribution dependent. I
> hope
> >> to
> >> > > > find the kernel version that this configuration stops working.
> >> > > >
> >> > > > Note on 4.x machines: If we do not have the correct ip assigned to
> >> the
> >> > > > tunnel interface we can see traffic on that interface. But, if we
> >> use the
> >> > > > correct VIP then we no longer see the traffic.
> >> > > >
> >> > > > I will keep you updated as I find information out.
> >> > > >
> >> > > > Thanks!
> >> > > > -Timothy
> >> > > >
> >> > > > On Tue, Jul 25, 2017 at 4:25 PM Julian Anastasov <ja at ssi.bg>
> wrote:
> >> > > >
> >> > > >>
> >> > > >>         Hello,
> >> > > >>
> >> > > >> On Fri, 14 Jul 2017, Timothy R. Weiand wrote:
> >> > > >>
> >> > > >> > I am building a DR-TUN configuration to load balance DNS
> traffic.
> >> My
> >> > > >> issue
> >> > > >> > is with the real servers: the ipip packet get unwrapped and
> >> appears on
> >> > > >> the
> >> > > >> > tunnel interface and becomes a martian. Also, I have not been
> >> able to
> >> > > >> > determine how to bind to the tunnel interface to capture these
> >> > > packets. I
> >> > > >> > have verified details with tcpdump/dmesg. All my configuration
> is
> >> > > >> scripted
> >> > > >> > to ensure reproducibility. tcpdumps below do not show real DNS
> >> > > traffic;
> >> > > >> > using netcat to send text.
> >> > > >> >
> >> > > >> > Much more detail can be supplied, please request it.
> >> > > >> >
> >> > > >> > Configuration:
> >> > > >> >
> >> > > >> > ==============
> >> > > >> >
> >> > > >> > - All machines are currently Debian 9 (4.9.30-2+deb9u2)
> >> > > >> >
> >> > > >> > - Client: 192.168.200.10
> >> > > >> >
> >> > > >> > - Director: 192.168.200.11
> >> > > >> >
> >> > > >> > - Real Server: 192.168.200.12
> >> > > >> >
> >> > > >> > - No VIP: I am using the IP address for my director interface -
> >> > > >> > 192.168.200.11
> >> > > >> >
> >> > > >> >
> >> > > >> > Director Configuration:
> >> > > >> >
> >> > > >> > ==================
> >> > > >> >
> >> > > >> > vagrant at debian-9-lb:~$ sudo ipvsadm -Ln
> >> > > >> >
> >> > > >> > IP Virtual Server version 1.2.1 (size=4096)
> >> > > >> >
> >> > > >> > Prot LocalAddress:Port Scheduler Flags
> >> > > >> >
> >> > > >> >   -> RemoteAddress:Port           Forward Weight ActiveConn
> >> InActConn
> >> > > >> >
> >> > > >> > UDP  192.168.200.11:53 rr
> >> > > >> >
> >> > > >> >   -> 192.168.200.12:53            Tunnel  1      0          0
> >> > > >> >
> >> > > >> >
> >> > > >> >
> >> > > >> > Real Server:
> >> > > >> >
> >> > > >> > ============
> >> > > >> >
> >> > > >> > # modprobe ipip
> >> > > >> >
> >> > > >> > # echo 1 > /proc/sys/net/ipv4/ip_forward
> >> > > >> >
> >> > > >> > # ip tunnel add tunl1 mode ipip ttl 32 local 192.168.200.12
> remote
> >> > > >> > 192.168.200.11
> >> > > >> >
> >> > > >> > # ip link set tunl1 up arp off
> >> > > >> >
> >> > > >> > # echo 2 > /proc/sys/net/ipv4/conf/all/rp_filter
> >> > > >> >
> >> > > >> > # echo 2 > /proc/sys/net/ipv4/conf/default/rp_filter
> >> > > >> >
> >> > > >> > # echo 2 > /proc/sys/net/ipv4/conf/tunl0/rp_filter
> >> > > >> >
> >> > > >> > # echo 2 > /proc/sys/net/ipv4/conf/tunl1/rp_filter
> >> > > >>
> >> > > >>         tunl1/rp_filter=2 is ignored if there are no
> >> > > >> IPv4 addresses configured on tunl1, you can see
> >> > > >> __fib_validate_source() for reference:
> >> > > >>
> >> > > >>         if (no_addr)
> >> > > >>                 goto last_resort;
> >> > > >>
> >> > > >>         As result, packets are dropped as martians due to rpf=2.
> >> > > >>
> >> > > >>         To check if packets are dropped by routing try:
> >> > > >>
> >> > > >> ip route get from 192.168.200.10 to 192.168.200.11 iif tunl1
> >> > > >>
> >> > > >>         Here is small howto for TUN (outdated):
> >> > > >>
> >> > > >> http://ja.ssi.bg/TUN-HOWTO.txt
> >> > > >>
> >> > > >> > vagrant at debian-9-dns:~$ sudo tcpdump -e -n -s 0 -i tunl1 -vv
> >> > > >> >
> >> > > >> > tcpdump: listening on tunl1, link-type RAW (Raw IP), capture
> size
> >> > > 262144
> >> > > >> > bytes
> >> > > >> >
> >> > > >> > 10:16:13.919646 ip: (tos 0x0, ttl 64, id 63545, offset 0, flags
> >> [DF],
> >> > > >> proto
> >> > > >> > UDP (17), length 40)
> >> > > >> >
> >> > > >> >     192.168.200.10.51149 > 192.168.200.11.53: [udp sum ok]
> 26226
> >> > > >> updateMA+
> >> > > >> > [b2&3=0x6f6d] [27753a] [11619q] [25966n] [29706au][|domain]
> >> > > >> >
> >> > > >> >
> >> > > >> >
> >> > > >> > If I add an IP address to the interface the packet never
> reaches
> >> tunl1
> >> > > >> >
> >> > > >> > # ip addr add 192.168.200.11/24 brd 192.168.200.11 dev tunl1
> >> > > >>
> >> > > >>         Try with (note mask /32):
> >> > > >>
> >> > > >> ip addr add 192.168.200.11/32 dev tunl1
> >> > > >>
> >> > > >>         as shown in LVS HOWTO (8.3):
> >> > > >>
> >> > > >>
> http://www.austintek.com/LVS/LVS-HOWTO/HOWTO/LVS-HOWTO.LVS-Tun.html
> >> > > >>
> >> > > >> > Notes:
> >> > > >> >
> >> > > >> > ======
> >> > > >> >
> >> > > >> >
> >> > > >> >
> >> > > >> > LVS-DR was not an option because the real servers will be in
> >> different
> >> > > >> > subnets (I was able to get LVS-DR working though).
> >> > > >> >
> >> > > >> >
> >> > > >> >
> >> > > >> > I am looking for advice on how to better understand or resolve
> >> this
> >> > > >> issue.
> >> > > >> > Or, who would be better to answer this question.
> >> > > >> >
> >> > > >> >
> >> > > >> >
> >> > > >> > I have groked as many articles on how to setup this
> configuration
> >> as I
> >> > > >> can.
> >> > > >> > And, I have read a good deal of the archives of this mailing
> list.
> >> > > >> >
> >> > > >> >
> >> > > >> >
> >> > > >> > Linux distributions I have tried are Debian, Ubuntu and Amazon
> >> linux.
> >> > > >> This
> >> > > >> > is been tested on both AWS and VMware fusion.
> >> > > >> >
> >> > > >> >
> >> > > >> >
> >> > > >> > ------
> >> > > >> >
> >> > > >> >
> >> > > >> >
> >> > > >> > I have a feeling I am missing something simple...
> >> > > >> >
> >> > > >> >
> >> > > >> >
> >> > > >> > Thanks!
> >> > > >> >
> >> > > >> > -Timothy
> >> > > >>
> >> > > >> Regards
> >> > > >>
> >> > > >> --
> >> > > >> Julian Anastasov <ja at ssi.bg>
> >> > > >>
> >> > > > _______________________________________________
> >> > > > Please read the documentation before posting - it's available at:
> >> > > > http://www.linuxvirtualserver.org/
> >> > > >
> >> > > > LinuxVirtualServer.org mailing list -
> >> lvs-users at LinuxVirtualServer.org
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> >> > > > or go to http://lists.graemef.net/mailman/listinfo/lvs-users
> >> > >
> >> > > _______________________________________________
> >> > > Please read the documentation before posting - it's available at:
> >> > > http://www.linuxvirtualserver.org/
> >> > >
> >> > > LinuxVirtualServer.org mailing list -
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> >> > >
> >> > _______________________________________________
> >> > Please read the documentation before posting - it's available at:
> >> > http://www.linuxvirtualserver.org/
> >> >
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> >>
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> >>
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> >
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