I couldn't find an answer or solution to my question in existing questions/answers on the net, so I have to write down my problem hoping that some expert spots the problem. Anyway here it goes.
I have 2 Ubuntu machines, configured that so that ipv4 is disabled and only IPv6 is enabled. One of them is the DUT the other the Tester.
DUT's configuration:
auto lo
iface lo inet loopback
iface lo inet6 loopback
auto ens1f0.101
iface eth1.101 inet6 static
address fd53:7cb8:383:101::121
netmask 48
Testers's configuration:
auto lo
iface lo inet loopback
iface lo inet6 loopback
auto eth1.101
iface eth1.101 inet6 static
address fd53:7cb8:383:1ff::141
netmask 48
They are both connected over an unmanaged L2 switch and I don't disable the network manager (as a utility as a side information)
Now, both Nodes can ping each other with ping6, like:
On Tester: ping6 -c 3 -I eth1.101 fd53:7cb8:383:101::121
On DUT: ping6 -c 3 -I ens1f0.101 fd53:7cb8:383:1ff::141
As I wanted to test the nodes with iperf3, it fails and I know that firewalls are disabled on both nodes.
On DUT I start iperf3 with:
iperf3 -6 -s -p 7001 -B fd53:7cb8:383:101::121
On Tester:
iperf3 -6 -c fd53:7cb8:383:101::121 -p 7001 -u -B fd53:7cb8:383:1ff::141 -b 10M -t 1
On Wireshark attached to ens1f0 at DUT I can see the TCP packets coming from Tester with correct VLAN ID set, with correct destination address and port settings, Client tries to establist connection with Server but Server does not react.
When I run netstat -ant, it shows me something like:
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp 0 0 127.0.0.53:53 0.0.0.0:* LISTEN
tcp 0 0 127.0.0.1:631 0.0.0.0:* LISTEN
tcp6 0 0 ::1:631 :::* LISTEN
tcp6 0 0 fd53:7cb8:383:101::7001 :::* LISTEN
But when I run nmap on Tester to scan ports on DUT, it returns nothing saying:
sudo nmap -e eth1.101 -6 fd53:7cb8:383:101::121 -Pnr -p1-8000
gives me:
Starting Nmap 7.60 ( https://nmap.org ) at 2018-11-23 13:01 CET
Nmap scan report for fd53:7cb8:383:101::121
Host is up (0.00031s latency).
All 8000 scanned ports on fd53:7cb8:383:101::121 are filtered
MAC Address: A0:36:9F:04:36:44 (Intel Corporate)
Nmap done: 1 IP address (1 host up) scanned in 174.62 seconds
Now I don't know what is wrong here.But I keep the eye on netstat report saying Local address f"d53:7cb8:383:101::7001" is listening but my Test machine prefix is fd53:7cb8:383:1ff. Could this be reason. Because when I change the Tester address to fd53:7cb8:383:101::xxx It works with iperf and Nmap and etc.
That means I thought two nodes fd53:7cb8:383:101::121 and fd53:7cb8:383:1ff::141 with netmask 48 should be able to find each other and communicate....they do..Ping works and TCP packets are arriving but those TCP packets are not answered and NMAP says all ports filtered even I know that Firewall is disabled.
I hope someone knows the answer to this.
Thank You Mtin
