iptables magic

[root@fedorahost ~]# iptables -L -n -v
Chain INPUT (policy ACCEPT 214 packets, 20051 bytes)
 pkts bytes target     prot opt in     out     source               destination

Chain FORWARD (policy ACCEPT 14 packets, 483 bytes)
 pkts bytes target     prot opt in     out     source               destination
    0     0 ACCEPT     udp  --  tun0   enp0s25  0.0.0.0/0            0.0.0.0/0            udp dpt:7011
    7   245 ACCEPT     udp  --  enp0s25 tun0    0.0.0.0/0            0.0.0.0/0            udp dpt:7011
    0     0 ACCEPT     udp  --  enp0s25 tun0    0.0.0.0/0            0.0.0.0/0            udp dpt:7700
    1   188 ACCEPT     udp  --  tun0   enp0s25  0.0.0.0/0            0.0.0.0/0            udp dpt:7700

Chain OUTPUT (policy ACCEPT 172 packets, 82904 bytes)
 pkts bytes target     prot opt in     out     source               destination
[root@fedorahost ~]# iptables -t nat -L -n -v
Chain PREROUTING (policy ACCEPT 4 packets, 804 bytes)
 pkts bytes target     prot opt in     out     source               destination
    2    60 DNAT       udp  --  *      *       0.0.0.0/0            0.0.0.0/0            udp dpt:7011 to:10.0.121.8:7000
    0     0 DNAT       tcp  --  *      *       0.0.0.0/0            0.0.0.0/0            tcp dpt:3389 to:10.0.121.2:3389
    1   188 DNAT       udp  --  *      *       10.8.0.0/24          0.0.0.0/0            udp dpt:7700 to:10.0.121.8:7700

Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination

Chain OUTPUT (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination

Chain POSTROUTING (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination
    3   248 MASQUERADE  all  --  *      enp0s25  0.0.0.0/0            0.0.0.0/0
    0     0 MASQUERADE  all  --  *      tun0    0.0.0.0/0            0.0.0.0/0

10:08:58.497766 IP (tos 0x0, ttl 63, id 13586, offset 0, flags [DF], proto UDP (17), length 188)
    10.8.0.14.7700 > 10.8.0.6.7700: [udp sum ok] UDP, length 160
        0x0000:  4500 00bc 3512 4000 3f11 f1fb 0a08 000e  E...5.@.?.......
        0x0010:  0a08 0006 1e14 1e14 00a8 7d58 8064 9f15  ..........}X.d..
        0x0020:  0000 0000 ac7a 2405 4100 0000 0000 0000  .....z$.A.......
        0x0030:  0000 0000 0000 0000 0000 0000 0000 0000  ................
        0x0040:  0000 0000 0000 0000 0000 0000 0000 0000  ................
        0x0050:  0000 0000 0000 0000 0000 0000 0000 0000  ................
        0x0060:  0000 0000 0000 0000 0000 0000 0000 0000  ................
        0x0070:  0000 0000 0000 0000 0000 0000 0000 0000  ................
        0x0080:  0000 0000 0000 0000 0000 0000 0000 0000  ................
        0x0090:  0000 0000 0000 0000 0000 0000 0000 0000  ................
        0x00a0:  0000 0000 0000 0000 0000 0000 0000 0000  ................
        0x00b0:  0000 0000 0000 0000 0000 0000            ............

10:02:22.601014 IP (tos 0x0, ttl 62, id 28979, offset 0, flags [DF], proto UDP (17), length 188)
    10.0.121.5.1024 > 10.0.121.8.7700: [udp sum ok] UDP, length 160
        0x0000:  4500 00bc 7133 4000 3e11 c4f0 0a00 7905  E...q3@.>.....y.
        0x0010:  0a00 7908 0400 1e14 00a8 63c8 8064 e0cf  ..y.......c..d..
        0x0020:  0000 0000 ac7a 2405 4100 0000 0000 0000  .....z$.A.......
        0x0030:  0000 0000 0000 0000 0000 0000 0000 0000  ................
        0x0040:  0000 0000 0000 0000 0000 0000 0000 0000  ................
        0x0050:  0000 0000 0000 0000 0000 0000 0000 0000  ................
        0x0060:  0000 0000 0000 0000 0000 0000 0000 0000  ................
        0x0070:  0000 0000 0000 0000 0000 0000 0000 0000  ................
        0x0080:  0000 0000 0000 0000 0000 0000 0000 0000  ................
        0x0090:  0000 0000 0000 0000 0000 0000 0000 0000  ................
        0x00a0:  0000 0000 0000 0000 0000 0000 0000 0000  ................
        0x00b0:  0000 0000 0000 0000 0000 0000