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djrollins

Member

From: Leeds, UK

Registered: 2016-07-11

Posts: 6

Website

OpenVPN client + update-systemd-resolved. DNS not working

Hi folks,

I'm having some serious trouble getting DNS working with OpenVPN. I know there has been some problems with permission changes in the latest versions of OpenVPN but everything _seems_ to execute cleanly so I think this is something different. I am not really a networking guy so I am genuinely at a loss of where to look next.

I have used Private Internet Access with OpenVPN for a few years, but I've recently installed arch on a new machine and it no longer seems to work. Trying to resolve any domain will just hang, but I am able to ping IP address directly.

I am using systemd-resolved, which is active and running, and my /etc/resolve.conf is symlinked to /run/systemd/resolve/stub-resolv.conf.

I installed openvpn-update-systemd-resolved from the AUR and added the recommended up/down script lines to my config. I also have the polkit rules setup to allow the openvpn user to set the DNS servers (but I don't think this is relevant as I am running openvpn with sudo?).

Here is my OpenVPN config. It is downloaded from the PIA website and I added the "auth-user-pass" line as well as the final block with the up/down scripts. (It's also worth noting that all files in the /etc/openvpn directory are owned by "openvpn:network").

client
dev tun
proto udp
remote uk-london.privacy.network 1198
resolv-retry infinite
nobind
persist-key
persist-tun
cipher aes-128-cbc
auth sha1
tls-client
remote-cert-tls server

auth-user-pass pia-credentials.txt
compress
verb 1
reneg-sec 0
<crl-verify>
-----BEGIN X509 CRL-----
MIICWDCCAUAwDQYJKoZIhvcNAQENBQAwgegxCzAJBgNVBAYTAlVTMQswCQYDVQQI
EwJDQTETMBEGA1UEBxMKTG9zQW5nZWxlczEgMB4GA1UEChMXUHJpdmF0ZSBJbnRl
cm5ldCBBY2Nlc3MxIDAeBgNVBAsTF1ByaXZhdGUgSW50ZXJuZXQgQWNjZXNzMSAw
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MR6jC0K2ps9qyZAN74LEBedEfK7tBOzWMwr58A==
-----END X509 CRL-----
</crl-verify>

<ca>
-----BEGIN CERTIFICATE-----
MIIFqzCCBJOgAwIBAgIJAKZ7D5Yv87qDMA0GCSqGSIb3DQEBDQUAMIHoMQswCQYD
VQQGEwJVUzELMAkGA1UECBMCQ0ExEzARBgNVBAcTCkxvc0FuZ2VsZXMxIDAeBgNV
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7pdw4Bvgoys2rHLHbGen7f28knT2j/cbMxd78tQc20TIObGjo8+ISTRclSTRBtyC
GohseKYpTS9himFERpUgNtefvYHbn70mIOzfOJFTVqfrptf9jXa9N8Mpy3ayfodz
1wiqdteqFXkTYoSDctgKMiZ6GdocK9nMroQipIQtpnwd4yBDWIyC6Bvlkrq5TQUt
YDQ8z9v+DMO6iwyIDRiU
-----END CERTIFICATE-----
</ca>

disable-occ
script-security 2
setenv PATH /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
up /etc/openvpn/scripts/update-systemd-resolved
up-restart
down /etc/openvpn/scripts/update-systemd-resolved
down-pre

Executing OpenVPN:

/etc/openvpn/client >>> sudo openvpn  uk_london.conf
[sudo] password for djr:
2021-02-08 20:58:30 DEPRECATED OPTION: --cipher set to 'aes-128-cbc' but missing in --data-ciphers (AES-256-GCM:AES-128-GCM). Future OpenVPN version will ignore --cipher for cipher negotiations. Add 'aes-128-cbc' to --data-ciphers or change --cipher 'aes-128-cbc' to --data-ciphers-fallback 'aes-128-cbc' to silence this warning.
2021-02-08 20:58:30 WARNING: file 'pia-credentials.txt' is group or others accessible
2021-02-08 20:58:30 OpenVPN 2.5.0 [git:makepkg/a73072d8f780e888+] x86_64-pc-linux-gnu [SSL (OpenSSL)] [LZO] [LZ4] [EPOLL] [PKCS11] [MH/PKTINFO] [AEAD] built on Nov  6 2020
2021-02-08 20:58:30 library versions: OpenSSL 1.1.1i  8 Dec 2020, LZO 2.10
2021-02-08 20:58:30 NOTE: the current --script-security setting may allow this configuration to call user-defined scripts
2021-02-08 20:58:30 CRL: loaded 1 CRLs from file -----BEGIN X509 CRL-----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-----END X509 CRL-----

2021-02-08 20:58:30 TCP/UDP: Preserving recently used remote address: [AF_INET]212.102.53.72:1198
2021-02-08 20:58:30 UDP link local: (not bound)
2021-02-08 20:58:30 UDP link remote: [AF_INET]212.102.53.72:1198
2021-02-08 20:58:30 WARNING: this configuration may cache passwords in memory -- use the auth-nocache option to prevent this
2021-02-08 20:58:31 [london405] Peer Connection Initiated with [AF_INET]212.102.53.72:1198
2021-02-08 20:58:32 sitnl_send: rtnl: generic error (-101): Network is unreachable
2021-02-08 20:58:32 TUN/TAP device tun0 opened
2021-02-08 20:58:32 net_iface_mtu_set: mtu 1500 for tun0
2021-02-08 20:58:32 net_iface_up: set tun0 up
2021-02-08 20:58:32 net_addr_v4_add: 10.60.112.115/24 dev tun0
2021-02-08 20:58:32 /etc/openvpn/scripts/update-systemd-resolved tun0 1500 1553 10.60.112.115 255.255.255.0 init
<14>Feb  8 20:58:32 update-systemd-resolved: Link 'tun0' coming up
<14>Feb  8 20:58:32 update-systemd-resolved: Adding IPv4 DNS Server 10.0.0.243
<14>Feb  8 20:58:32 update-systemd-resolved: SetLinkDNS(16 1 2 4 10 0 0 243)
2021-02-08 20:58:32 WARNING: OpenVPN was configured to add an IPv6 route. However, no IPv6 has been configured for tun0, therefore the route installation may fail or may not work as expected.
2021-02-08 20:58:32 add_route_ipv6(2000::/3 -> :: metric -1) dev tun0
2021-02-08 20:58:32 Initialization Sequence Completed

resolvectl status:

~ >>> resolvectl status
Global
           Protocols: +LLMNR +mDNS -DNSOverTLS DNSSEC=no/unsupported
    resolv.conf mode: stub
Fallback DNS Servers: 1.1.1.1 9.9.9.10 8.8.8.8 2606:4700:4700::1111 2620:fe::10 2001:4860:4860::8888

Link 2 (enp10s0)
    Current Scopes: DNS LLMNR/IPv4 LLMNR/IPv6
         Protocols: +DefaultRoute +LLMNR -mDNS -DNSOverTLS DNSSEC=no/unsupported
Current DNS Server: 194.168.8.100
       DNS Servers: 194.168.4.100 194.168.8.100

Link 16 (tun0)
Current Scopes: LLMNR/IPv4 LLMNR/IPv6
     Protocols: -DefaultRoute +LLMNR -mDNS -DNSOverTLS DNSSEC=no/unsupported

I'd be grateful for any ideas on what to try to resolve this issue. Or even a recommendation for a different approach entirely to getting OpenVPN working.

Cheers.

TheLateJC

Member

Registered: 2009-01-29

Posts: 6

Re: OpenVPN client + update-systemd-resolved. DNS not working

I've decided to have a crack at fixing my long running issues with this today. I'm using the update-resolv-conf script, and I noticed that my VPN provider supplies 2 DNS entries, and somehow the script borks itself.

As a temp workaround I replaced:

  echo -n "$R" | $RESOLVCONF -x -a "${dev}.inet" 

with:

  echo -n "nameserver $NS" | $RESOLVCONF -x -a "${dev}.inet"

resolvectl dns posts stuff that makes little sense

If you want, you can try adding the following into the up script, and it might post some interesting information for you:

 set -x 

 

I have a similar config to yours, bar the up script, and by the looks of it we might have similar purpose. I hope you get sorted in time.

--
JC

TheLateJC

Member

Registered: 2009-01-29

Posts: 6

Re: OpenVPN client + update-systemd-resolved. DNS not working

Huh... try this: https://aur.archlinux.org/packages/open … -resolved/

Works out of the box for me, which is nice.