[Openswan Users] openswan, alias interface and advanced routing (very long)
Giovani Moda - MR Informática
giovani at mrinformatica.com.br
Tue Oct 23 14:10:32 EDT 2007
Hello,
It's been a while since I don't need your help, but I've been pulling my hair out on this one and can't seem to figure it out. Here it goes:
I have two servers connected trhough three tunnels:
net1-to-net2
server1-to-net2
net1-to-server2
In this particular case, I had to create the tunnels using an alias interface of eth0, since the servers exchange non encrypted communication, wich is huge and would overload the tunnels if encrypted. In both servers, the external interface is eth0, and there are aliases interfaces eth0:0. I can do that, since both ends have up to four valid ips I can use. So, the scenario is something like:
net1 -> eth0:0 -> eth0 -> internet -> eth0 -> eth0:0 -> net2
To make things more difficult (of course), at server1, there's a second internet link, on wich there are traffic control rules. That would be eth2. To acomplish the balancing between those links, a set of advanced rules using ip rule have been created. I'll not mention the HTB rules here, since they are specifically bonded to eth2, and only eth2. And that's where all the problems began. It was all working 'till I've added that second link and subsequent advanced rules.
Here are the advanced routing rules:
ip rule
0: from all lookup local
18: from all fwmark 0x3 lookup router1
19: from all fwmark 0x4 lookup router2
20: from all fwmark 0x5 lookup router3
22: from 189.2.x.x lookup router3 --> ip of eth0:0
22: from 189.2.x.x lookup router1 --> ip of eth0
23: from 189.19.x.x lookup router2 --> ip of eth2
32766: from all lookup main
32767: from all lookup default
ip route show main
189.2.x.x via 189.2.x.x dev ipsec1
189.2.x.x/26 dev eth0 proto kernel scope link src 189.2.x.x
189.2.x.x/26 dev ipsec0 proto kernel scope link src 189.2.x.x
189.2.x.x/26 dev ipsec1 proto kernel scope link src 189.2.x.x
189.19.x.x/24 dev eth2 proto kernel scope link src 189.19.x.x
172.31.72.0/22 via 189.2.x.x dev ipsec1
172.31.68.0/22 dev eth1 proto kernel scope link src 172.31.68.1
default
nexthop via 189.2.x.x dev eth0 weight 1
nexthop via 189.19.x.x dev eth2 weight 1
ip route show table router1
189.2.x.x/26 dev eth0 scope link src 189.2.x.x --> ip of eth0
189.19.x.x/24 dev eth2 scope link src 189.19.x.x
172.31.68.0/22 dev eth1 scope link src 172.31.68.1
127.0.0.0/8 dev lo scope link
default via 189.2.x.x dev eth0 src 189.2.x.x --> ip of eth0
ip route show table router2
189.2.x.x/26 dev eth0 scope link src 189.2.x.x
189.19.x.x/24 dev eth2 scope link src 189.19.x.x
172.31.68.0/22 dev eth1 scope link src 172.31.68.1
127.0.0.0/8 dev lo scope link
default via 189.19.x.x dev eth2 src 189.19.x.x --> ip from eth2
ip route show table router3
189.2.x.x/26 dev eth0 scope link src 189.2.x.x --> ip of eth0:0
189.19.x.x/24 dev eth2 scope link src 189.19.x.x
172.31.68.0/22 dev eth1 scope link src 172.31.68.1
127.0.0.0/8 dev lo scope link
default via 189.2.x.x dev eth0 src 189.2.x.x --> ip of eth0:0
Some iptables rules to direct the traffic to it's desirable destination:
$IPTABLES -t nat -A POSTROUTING -o eth0 -j SNAT --to-source 189.2.x.x # make eth0 traffic go through eth0
$IPTABLES -t nat -A POSTROUTING -o eth2 -j SNAT --to-source 189.19.x.x # make eth2 traffic go through eth2
$IPTABLES -t mangle -A PREROUTING -p tcp -i eth1 --dport 80 -j MARK --set-mark 3 # http-trafic
$IPTABLES -t mangle -A PREROUTING -p tcp -i eth1 --dport 443 -j MARK --set-mark 3 # http-trafic
$IPTABLES -t mangle -A PREROUTING -p tcp -i eth1 --dport 25 -j MARK --set-mark 4 # smtp
$IPTABLES -t mangle -A PREROUTING -p tcp -i eth1 --dport 110 -j MARK --set-mark 4 # pop3
$IPTABLES -t mangle -A PREROUTING -p tcp -i eth1 --dport 143 -j MARK --set-mark 4 # imap
$IPTABLES -t mangle -A PREROUTING -p tcp -i eth1 --dport 20 -j MARK --set-mark 4 # ftp
$IPTABLES -t mangle -A PREROUTING -p tcp -i eth1 --dport 21 -j MARK --set-mark 4 # ftp
$IPTABLES -t mangle -A PREROUTING -p udp -i eth1 --dport 500 -j MARK --set-mark 5 # ipsec identify redirected to table router3
$IPTABLES -t mangle -A PREROUTING -p udp -i eth1 --dport 4500 -j MARK --set-mark 5 # ipsec nat-t redirected to table router3
$IPTABLES -t mangle -A PREROUTING -p ah -j MARK --set-mark 5 # ipsec trafic redirected to table router3
$IPTABLES -t mangle -A PREROUTING -p esp -j MARK --set-mark 5 # ipsec trafic redirected to table router3
$IPTABLES -t mangle -A POSTROUTING -p ah -j MARK --set-mark 5 # ipsec trafic redirected to table router3
$IPTABLES -t mangle -A POSTROUTING -p esp -j MARK --set-mark 5 # ipsec trafic redirected to table router3
$IPTABLES -t mangle -A OUTPUT -p tcp --dport 80 -j MARK --set-mark 3 # http-trafic
$IPTABLES -t mangle -A OUTPUT -p tcp --dport 443 -j MARK --set-mark 3 # http-trafic
$IPTABLES -t mangle -A OUTPUT -p tcp --dport 25 -j MARK --set-mark 4 # smtp
$IPTABLES -t mangle -A OUTPUT -p tcp --dport 110 -j MARK --set-mark 4 # pop3
$IPTABLES -t mangle -A OUTPUT -p tcp --dport 20 -j MARK --set-mark 4 # ftp
$IPTABLES -t mangle -A OUTPUT -p tcp --dport 21 -j MARK --set-mark 4 # ftp
$IPTABLES -t mangle -A OUTPUT -p udp --dport 500 -j MARK --set-mark 5 # ipsec identify redirected to table router3
$IPTABLES -t mangle -A OUTPUT -p udp --dport 4500 -j MARK --set-mark 5 # ipsec nat-t redirected to table router3
and finally my ipsec.conf
#
config setup
klipsdebug=none
plutodebug=none
interfaces="ipsec0=eth0 ipsec1=eth0:0"
nat_traversal=yes
uniqueids=yes
virtual_private=%v4:10.0.0.0/8,%v4:!172.31.0.0/12,%v4:192.168.0.0/24,%v4:192.168.1.0/24,%v4:192.168.2.0/24
conn %default
compress=yes
disablearrivalcheck=no
conn sp-to-pira
keyingtries=0
authby=rsasig
left=189.2.x.x --> ip of eth0:0
leftnexthop=189.2.x.x
leftsubnet=172.31.68.0/22
leftid=@pira...
leftrsasigkey=
right=189.2.x.x
rightnexthop=189.2.x.x
rightsubnet=172.31.72/22
rightrsasigkey=
rightid=@sp...
auto=start
conn sp-to-piranet
keyingtries=0
authby=rsasig
left=189.2.x.x --> ip of eth0:0
leftnexthop=189.2.x.x
leftsubnet=172.31.68.0/22
leftid=@pira...
leftrsasigkey=
right=189.2.x.x
rightnexthop=189.2.x.x
rightrsasigkey=
rightid=@sp....
auto=start
conn pira-to-spnet
keyingtries=0
authby=rsasig
left=189.2.x.x --> ip of eth0:0
leftnexthop=189.2.x.x
leftid=@pira...
leftrsasigkey=
right=189.2.x.x
rightnexthop=189.2.x.x
rightsubnet=172.31.72.0/22
rightrsasigkey=
rightid=@sp...
auto=start
conn MR-AS
authby=rsasig
rightcert=mr.pem
rightid="C=BR..."
auto=add
also=l2tp-ipsec
conn RD1-AS
authby=rsasig
rightcert=rd1.pem
rightid="C=BR..."
auto=add
also=l2tp-ipsec
conn l2tp-ipsec
pfs=no
left=189.2.x.x --> ip of eth0
leftcert=mail1.pem
leftrsasigkey=%cert
leftsendcert=yes
leftprotoport=17/1701
right=%any
rightca=%same
rightprotoport=17/1701
rightrsasigkey=%cert
rightsubnet=vhost:%no,%priv
rekey=no
include /etc/ipsec.d/examples/no_oe.conf
#
So, all server-to-server and net-to-net traffic is supposed to go through eth0:0 IP, and all roadwarrios connections through eth0 IP. The problem is: it's not. All ipsec thaffic is reaching the other end with IP from eth0, and not eth0:0, giving me this at server2:
pluto[869]: packet from 189.2.x.x:500 (server1 eth0:0): initial Main Mode message received on 189.2.x.x:500 (server2 eth0:0) but no connection has been authorized. (obviously)
And the MOST curious is that in server1 logs, I get a tunnel estabilished through NAT-T with server2:
pluto[1490]: "sp-to-piranet" #38: NAT-Traversal: Result using RFC 3947 (NAT-Traversal): peer is NATed
pluto[1490]: "sp-to-piranet" #38: STATE_MAIN_R3: sent MR3, ISAKMP SA established {auth=OAKLEY_RSA_SIG cipher=oakley_3des_cbc_192 prf=oakley_md5 group=modp1536}
Biy server2 IS NOT nated. There's a route mix up somewhere wich leads server1 to believe that packets delivered to eth0:0 are being nated.
So, as result, from server2 I can ping both server1 and subnet1, but not the other way around. Except if I ping explicitly from the internel interface (eth1), wich does not work for my purposes.
ping 172.31.72.2
PING 172.31.72.2 (172.31.72.2) 56(84) bytes of data.
--- 172.31.72.2 ping statistics ---
2 packets transmitted, 0 received, 100% packet loss, time 999ms
ping -I eth1 172.31.72.2
PING 172.31.72.2 (172.31.72.2) from 172.31.68.1 eth1: 56(84) bytes of data.
64 bytes from 172.31.72.2: icmp_seq=1 ttl=127 time=37.1 ms
64 bytes from 172.31.72.2: icmp_seq=2 ttl=127 time=33.9 ms
64 bytes from 172.31.72.2: icmp_seq=3 ttl=127 time=33.8 ms
--- 172.31.72.2 ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2000ms
All roadwarriors connections are working. I'm pretty sure the problem relies on:
$IPTABLES -t nat -A POSTROUTING -o eth0 -j SNAT --to-source 189.2.x.x
But I cannot make the advanced rules work without it. I've already tried. And I can't find a way to tell iptables to not SNAT packets with source IP of eth0:0. So, can anyone please help me? Any suggestion would be dearly appreciated.
Thanks, and sorry for the very, very long post.
Giovani Moda
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