I finally found a working solution, not a VZ pb but rather an
openvpn-server configuration => I move to "proto tcp" instead of "proto
udp" ! both proto worked to open the VPN , but with udp routing didn't
worked,
thanks to your 5 steps check procedure I realized that at step 3)
"tcpdump on vpn's tun device to check that the packets do arrive",
packets didn't arrived at vpn's tun0 interface. moving both client and
server to tcp , then it worked .
Perhaps I have a pb with SNAT / iptables while using UDP ? , but setting
the following iptables rules works fine in TCP :
*nat
:PREROUTING ACCEPT [0:0]
:POSTROUTING ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
-A POSTROUTING -o eth0 -j SNAT --to-source 157.109.2.13
while it works fine in TCP I will still investigate on UDP as it seems
to be better optimize for VPNs: cf
https://hamy.io/post/0002/openvpn-tcp-or-udp-tunneling/
Back to VZ initial questions:
2) refering to
https://docs.virtuozzo.com/virtuozzo_7_users_guide/managing-network/networking-modes-in-virtuozzo.html
I do use bridge mode, I have veth interfaces on server host and eth0
counterparts on containers
2.1) it should be working with firewalld as describe in NAT section of
https://r.je/openvpn-nat
or in step 11 of : https://tecadmin.net/install-openvpn-centos-8/
but for the sake of simplicity I revert back to iptables
https://www.digitalocean.com/community/tutorials/how-to-migrate-from-firewalld-to-iptables-on-centos-7
other usefull link
https://wiki.archlinux.org/index.php/OpenVPN_server_in_Linux_Containers
2.3) I kept using eth0 and it work fine, I suppose that I see
eth0@if*70* because on the server host there's a corresponding
*70*: vme001851fefa53@if3 <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500
qdisc noqueue master br2 state UP group default qlen 1000
probably a "link" between both counterpart of host veth and CT eth0 !?
2.4) rp_filter is set to 1 , howerver it works fine now (tcp)
CT# cat /proc/sys/net/ipv4/conf/all/rp_filter
1
I can set it to 0 , but I am not sure it is interpreted as is in the CT
context, or is the /proc/sys/net/ipv4/conf/all/rp_filter value on the
server host prevalent ? both share the same kernel , do they share /proc ?
thanks for your detailed help .
regards .
Le 25/02/2020 à 22:11, Dmitry Konstantinov a écrit :
1) I meant you don't need any special capabilities to run openvpn.
Just the tun device should be available.
2) Sorry for the confusion, I meant the openvz networking. routed (venet
device) or bridged (veth).
2.1) I don't use firewalld and not familiar with its syntax.
2.2) it really depends on how you wish the packets to travel.
if they are supposed to go through eth0 then you need to use
eth0 in all the configurations.
2.3) I honestly don't know if a name like eth0@if248 is going to
be accepted by the tools.
2.4) I am not sure but probably in case of bridged networking
you will need to disable rp_filter. Not necessarily, depends on
your configuration. Set the sysctl variable to zero.
Example:
In my particular case openvpn is used to access private network at
remote location. I've got two addresses configured on venet0 device,
let's say 123.124.125.126 and 192.168.192.168.
Private network is 192.168.192.0/24
openvpn uses 192.168.10.0/28 internal subnet with 192.168.10.1 being
assigned to tun0
openvpn config:
--
topology subnet
ifconfig 192.168.10.1 255.255.255.240
mode server
server 192.168.10.0 255.255.255.240
push "route 192.168.192.0 255.255.255.0"
--
sysctl.conf:
net.ipv4.ip_forward = 1
iptables:
:POSTROUTING ACCEPT [0:0]
[0:0] -A POSTROUTING -s 192.168.10.0/28 -j SNAT --to-source
192.168.192.168
COMMIT
That's all
now let's say I know for sure 192.168.192.100 is up and running in
the private network. I have an established connection to the vpn
from my local machine and try to ping it but there's no response.
I'd probably check things in the following order:
1) ip a l; ip r l on local machine to check that I have the connectiom
established and the route active
2) tcpdump on local tun device to check that the packets do leave
3) tcpdump on vpn's tun device to check that the packets do arrive
4) tcpdump on vpn's eth/venet device to check if the packets are routed
between interfaces and have the source address changed.
5) ping from vpn container - you might have weird filtering on the
server that hosts the container.
On Tue, 25 Feb 2020 16:32:43 +0100
Jehan Procaccia <jehan.procac...@imtbs-tsp.eu> wrote:
OK for 1) , then I don't need any capability (net_admin, sys_time), I
was wondering because I read that on lots of docs as in :
https://github.com/OpenVZ/vz-docs/blob/master/virtuozzo_7_users_guide.asc
perhaps deprecated ?
for 2) I use routed openvpn (tun0)
yes I mess a lot between iptables and firewalld while debungin my pb
2.1) I would prefere to use firewalld , can you confirm me the rule
you use ?
POSTROUTING with masquerade or have you an iptable SNAT exemple ?
2.2) if I use a eth0 interface do you confirm that venet0 (that is
Down on my CT) is not concerned at all ?
2.3) my eth0 appears as eth0@if248 (ip addr) , is it important for
the firewall-cmd command arguments => "-o eth0" ? should I use -o
eth0@if248 ! 2.4) what do you mean by |rp_filter| (reverse path
filtering), should I disable it , how ?
Thanks .
Le 25/02/2020 à 14:54, Dmitry Konstantinov a écrit :
openvpn does work. dev/tun:rw and full netfilter is all the
'extras' I have in the container's config
1) not sure if it's still works but probably not useful in
this particular case, never used any capabilities for openvpn.
2) I use a single postrouting rule. Like the last one in your list.
I don't quite understand your setup. Do you use routed or bridged
networking? with firewalld you configure eth0 but I see venet0 in
iptables. I don't have much experience with eth devices inside
container, perhaps you might need to configure rp_filter for it
to work with openvpn.
On Tue, 25 Feb 2020 10:21:33 +0100
Jehan Procaccia <jehan.procac...@imtbs-tsp.eu> wrote:
Hello
I have running VPNs that works perfectly on openvz6 , now I move to
openvz7 and I cannot make it forward or masquerade between
interfaces .
I am questionning about different concepts:
1) is enabling capablities still enable/usefull ?
ie: prlctl set ctvpn --capability net_admin:on => doesn't save
anything in the CT conf ...
I did set
prlctl set ctvpn --netfilter full => in order to have nat and
mangle chains
2) is using iptables or firewalld determinent ? masquerade or
SNAT ?
neither of those works
for Masquerade I did
firewall-cmd --permanent --direct --passthrough ipv4 -t nat -A
POSTROUTING -s 10.91.10.0/22 -o eth0 -j MASQUERADE
for iptables I tried with
*nat
:PREROUTING ACCEPT [0:0]
:POSTROUTING ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
-A POSTROUTING -o venet0 -j SNAT --to-source 157.109.2.13
-A POSTROUTING -s 10.91.10.0/22 -j SNAT --to-source 157.109.2.13
by the way is venet0 important as it appears down in the CT !?
2: venet0: <BROADCAST,POINTOPOINT,NOARP> mtu 1500 qdisc noop state
DOWN group default
link/void
3: eth0@if248: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc
noqueue state UP group default qlen 1000
dev/tun is working correctly
I set it with: vzctl set ctvpn --devnodes net/tun:rw --save
CT-ABC /# ls -l /dev/net/tun
crw-rw-rw- 1 root root 10, 200 Feb 25 10:07 /dev/net/tun
CT-ABC /# cat /dev/net/tun
cat: /dev/net/tun: File descriptor in bad state
=> message that means it is operational !
openvpn uses tun interface, connecting clients to openvpn server
works fine, but routing between interfaces (tun0 and eth0 ) doesn't
work .
of course ip_forward is enabled
CT-ABC /# cat /proc/sys/net/ipv4/ip_forward
1
Thanks for your help .
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