openconnect is connected but does not use the right dns

sudo openconnect --protocol=nc [corporate vpn url] GET [corporate vpn url] Connected to [corporate vpn ip]:443 SSL negotiation with [corporate vpn url] Connected to HTTPS on [corporate vpn url] Got HTTP response: HTTP/1.1 302 Found GET [corporate vpn url]/auth/url_13/welcome.cgi SSL negotiation with [corporate vpn url] Connected to HTTPS on [corporate vpn url] frmLogin username: [a username] password: [a password] POST [corporate vpn url]/auth/url_13/login.cgi Got HTTP response: HTTP/1.1 302 Moved GET [corporate vpn url]/home/starter0.cgi?check=yes Connected as [new ip address], using SSL, with ESP in progress ESP session established with server 

It seems to be fine in the sense that torguard shows a different IP address and country before and after the openconnect is connected.

However it seems I cannot access to the corporate websites, when I try with say Chrome, I end up with:

Server IP address could not be found. DNS_PROBE_FINISHED_NXDOMAIN 

Like if the dns wasn't fetched or something like.

It's weird though cause when I am doing this from a live cd, that is without any prior connection to any network, it works just fine...

I am wondering how the DNS is fetched.

[EDIT]

I am right now using Linux Mint live to see what is the DNS in use or is there anything special setup:

For the Wireless connection:

mint@mint:~$ nmcli device show wlp1s0 GENERAL.DEVICE: wlp1s0 GENERAL.TYPE: wifi GENERAL.HWADDR: E0:94:67:32:46:AF GENERAL.MTU: 1500 GENERAL.STATE: 100 (connected) GENERAL.CONNECTION: [our wireless hotspot at home] GENERAL.CON-PATH: /org/freedesktop/NetworkManager/ActiveConnection/1 IP4.ADDRESS[1]: 192.168.1.104/24 IP4.GATEWAY: 192.168.1.1 IP4.ROUTE[1]: dst = 0.0.0.0/0, nh = 192.168.1.1, mt = 600 IP4.ROUTE[2]: dst = [what an ip address?!], nh = 0.0.0.0, mt = 600 IP4.ROUTE[3]: dst = [yet another one!], nh = 0.0.0.0, mt = 1000 IP4.ROUTE[4]: dst = [an address, geez], nh = 192.168.1.1, mt = 0 IP4.DNS[1]: 192.168.1.1 IP4.DOMAIN[1]: home IP6.ADDRESS[1]: [ipv 6 craziness] IP6.ADDRESS[2]: [woooa] IP6.ADDRESS[3]: [asdasdad] IP6.GATEWAY: [&*^$] IP6.ROUTE[1]: dst = [incredible]::/64, nh = ::, mt = 600 IP6.ROUTE[2]: dst = ::/0, nh = [beyond understanding], mt = 600 IP6.ROUTE[3]: dst = ff00::/8, nh = ::, mt = 256, table=255 IP6.ROUTE[4]: dst = fe80::/64, nh = ::, mt = 256 IP6.ROUTE[5]: dst = fe80::/64, nh = ::, mt = 600 IP6.DNS[1]: [fantastic!] 

And the VPN created interface:

mint@mint:~$ nmcli device show tun0 GENERAL.DEVICE: tun0 GENERAL.TYPE: tun GENERAL.HWADDR: (unknown) GENERAL.MTU: 1400 GENERAL.STATE: 100 (connected) GENERAL.CONNECTION: tun0 GENERAL.CON-PATH: /org/freedesktop/NetworkManager/ActiveConnection/2 IP4.ADDRESS[1]: [magic ip] IP4.GATEWAY: 0.0.0.0 IP4.ROUTE[1]: dst = [magic ip], nh = 0.0.0.0, mt = 0 IP4.ROUTE[2]: dst = 0.0.0.0/0, nh = 0.0.0.0, mt = 0 IP6.ADDRESS[1]: [magic ip again] IP6.GATEWAY: -- IP6.ROUTE[1]: dst = ff00::/8, nh = ::, mt = 256, table=255 IP6.ROUTE[2]: dst = fe80::/64, nh = ::, mt = 256 

Interestingly enough, it seems that the etc/resolv.conf has been changed when I connected to the vpn:

#@VPNC_GENERATED@ -- this file is generated by vpnc # and will be overwritten by vpnc # as long as the above mark is intact # This file is managed by man:systemd-resolved(8). Do not edit. # # This is a dynamic resolv.conf file for connecting local clients to the # internal DNS stub resolver of systemd-resolved. This file lists all # configured search domains. # # Run "systemd-resolve --status" to see details about the uplink DNS servers # currently in use. # # Third party programs must not access this file directly, but only through the # symlink at /etc/resolv.conf. To manage man:resolv.conf(5) in a different way, # replace this symlink by a static file or a different symlink. # # See man:systemd-resolved.service(8) for details about the supported modes of # operation for /etc/resolv.conf. options edns0 nameserver [some address 1] nameserver [some address 2] search home [loads of corporate related names] 

... and when I disconnect from the VPN:

# This file is managed by man:systemd-resolved(8). Do not edit. # # This is a dynamic resolv.conf file for connecting local clients to the # internal DNS stub resolver of systemd-resolved. This file lists all # configured search domains. # # Run "systemd-resolve --status" to see details about the uplink DNS servers # currently in use. # # Third party programs must not access this file directly, but only through the # symlink at /etc/resolv.conf. To manage man:resolv.conf(5) in a different way, # replace this symlink by a static file or a different symlink. # # See man:systemd-resolved.service(8) for details about the supported modes of # operation for /etc/resolv.conf. nameserver 127.0.0.53 options edns0 search home 

3 Answers

I found something that works from an answer on the Manjaro Forum: Weird DNS issue over VPN

So basically what did I do:

• sudo systemctl stop systemd-resolved
• sudo systemctl disable systemd-resolved
• Remove symlink between /etc/resolv.conf and /run/systemd/resolve/resolv.conf
• Comment out the line with hosts: ... in /etc/nsswitch.conf
• Reboot

Tbh, it's still a bit voodoo to me about why it works.

The hypothetical underlying reason about why this works from the author is pasted below:

My understanding is that commenting out the line with hosts in /etc/nsswitch.conf allows sudo openconnect to work without systemd-resolved. Indeed, openconnect relies on /etc/vpnc/vpnc-script to detect which type of DNS resolver is used and if it finds a row containing the word "resolve" in /etc/nsswitch.conf, it thinks systemd-resolved is being used even if it is disabled.

This is why I got an error when using sudo openconnect with systemd-resolved disabled. And this is also why I did enable this service afterwards. However it seems this caused some errors and even if the symlink technique did work, I was still having some issues with DNS leaks. Well, simply commenting this line in /etc/nsswitch.conf is what is recommended in the above link and it indeed works. Now, although systemd-resolved is being disabled (the default in Manjaro apparently), sudo openconnect does't complain anymore about it and works properly.

I don't know whether vpnc-script is at fault here: it should not detect systemd-resolved as the DNS resolver being used based on that row in nsswitch.conf. It should check if systemd-reolved is enabled IMHO.

I had this issue. I was due to a known bug. This workaround worked for me:

add this to /etc/network/if-up.d/globalprotect:

#!/bin/sh # Hacky workaround bug in NM not setting the default routes. if [ "$IFACE" = "vpn0" ]; then ip route replace default via 0.0.0.0 dev vpn0 fi 

Try to flush dns.

• Launch Terminal by pressing Ctrl+Alt+T.

• Type the following command, then press Enter:

  sudo /etc/init.d/dns-clean restart 

• Now, type

  sudo /etc/init.d/networking force-reload 

• Press Enter.