vpn-over-ssh ipv6 tunnel getting permission denied connecting to tcp

Using my script, I can establish a working vpn for ipv4 and even able to ping ipv6 addresses.

However, trying to connect to an ipv6 address I get "permission denied".

➜ ping -6 ipv6.google.com -c1
PING ipv6.google.com(lga15s45-in-x0e.1e100.net (2607:f8b0:4006:809::200e)) 56 data bytes
64 bytes from lga15s45-in-x0e.1e100.net (2607:f8b0:4006:809::200e): icmp_seq=1 ttl=58 time=165 ms

--- ipv6.google.com ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 165.053/165.053/165.053/0.000 ms

➜ curl -6 ipv6.google.com 
curl: (7) Failed to connect to ipv6.google.com port 80: Permission denied

• Neither the server nor the client have selinux enabled.
• ipv4 works perfectly.
• ip forwarding for both ipv4 and ipv6 is enabled on both.
• masquerading is enabled on both.

I'm completely out of ideas.

// edit

Arch Linux 64bit kernel 4.4.5