OpenVPN Support Forum

First of all, thanks for providing the iOS OpenVPN client and working through the issues with Apple.

I've been using OpenVPN when I'm traveling to connect back to my home network where I have both IPv4 & IPv6 available. Rather than using the subnet topology I'm using the net30 topology, which works fine for for IPv4 & IPv6 for MacOS. I don't want to use subnet because of the amount of broadcast traffic. However, the iOS port barf's over this configuration (see the log file below). My temporary work around is to stop pushing the IPv6 configuration.

Is this going to be fixed in some future version?

Thanks, Leendert

2013-03-16 16:26:35 SSL Handshake: TLSv1.0/SSL-EDH-RSA-AES-256-SHA
2013-03-16 16:26:35 Session is ACTIVE
2013-03-16 16:26:36 EVENT: GET_CONFIG
2013-03-16 16:26:36 Sending PUSH_REQUEST to server...
2013-03-16 16:26:36 OPTIONS:
0 [ifconfig-ipv6] [xxx:xxxx:xxxx::8000::1000/64] [xxxx:xxxx:xxxx:8000::1]
1 [route] [10.128.0.1] [255.255.255.255]
2 [route] [10.0.0.0] [255.255.255.0]
3 [redirect-gateway] [def1]
4 [route-ipv6] [::/0] [xxxx:xxxx:xxxx:8000::1]
5 [dhcp-option] [DOMAIN] [example.com]
6 [dhcp-option] [DNS] [10.0.0.71]
7 [dhcp-option] [WINS] [10.0.0.71]
8 [dhcp-option] [NTP] [10.0.0.71]
9 [tun-ipv6]
10 [route] [10.128.0.1]
11 [topology] [net30]
12 [ping] [10]
13 [ping-restart] [60]
14 [ifconfig] [10.128.0.6] [10.128.0.5]

2013-03-16 16:26:36 LZO-ASYM init swap=0 asym=0
2013-03-16 16:26:36 EVENT: ASSIGN_IP
2013-03-16 16:26:36 TUN Error: option_error: only topology 'subnet' supported with IPv6
2013-03-16 16:26:36 EVENT: TUN_SETUP_FAILED option_error: only topology 'subnet' supported with IPv6 [ERR]
2013-03-16 16:26:36 EVENT: DISCONNECTED

Don't worry -- using "topology subnet" doesn't increase broadcast traffic. Broadcast traffic would only be increased if you used layer 2 tunneling (i.e. "dev tap") which isn't supported on iOS anyway.

Ah, thanks for that hint. I never looked into subnet over tun but that works. I added the following to my server config file to make IPv4/IPv6 work for OpenVPN:

# Use subnet topology
topology subnet

# IPv6 network (route everything)
server-ipv6 xxxx:xxxx:xxxx:8000::/64