Static route ping but no other connection

Installing and Using OpenWrt Network and Wireless Configuration
21

This is my iptables configuration

Chain POSTROUTING (policy ACCEPT 561K packets, 42M bytes)
 pkts bytes target     prot opt in     out     source               destination         
 2215  200K SNAT       all  --  *      tun57   192.168.55.0/24      0.0.0.0/0            to:192.168.57.2

where 57.2 is the ip assigned by vpn server to gateway.

I added this configuration by:

iptables -t nat -A POSTROUTING -s 192.168.55.0/24 -o tun57 -j SNAT --to-source 192.168.57.2

What is wrong in this configuration?

Thank you for your patince and your help.

22

Can you show us the configuration of the vpn server 55.4?
network, firewall, and openvpn.

23

This is 55.4 network configuration:

eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.55.4  netmask 255.255.255.0  broadcast 192.168.55.255
        inet6 fe80::ba27:ebff:fe25:1818  prefixlen 64  scopeid 0x20<link>
        ether b8:27:eb:25:18:18  txqueuelen 1000  (Ethernet)
        RX packets 3490416118  bytes 4937552053312 (4.4 TiB)
        RX errors 0  dropped 1761  overruns 0  frame 0
        TX packets 1949716256  bytes 474819067323 (442.2 GiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
        inet 127.0.0.1  netmask 255.0.0.0
        inet6 ::1  prefixlen 128  scopeid 0x10<host>
        loop  txqueuelen 1000  (Local Loopback)
        RX packets 2828143  bytes 341585340 (325.7 MiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 2828143  bytes 341585340 (325.7 MiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

tun57: flags=4305<UP,POINTOPOINT,RUNNING,NOARP,MULTICAST>  mtu 1500
        inet 192.168.57.2  netmask 255.255.255.255  destination 192.168.57.2
        inet6 fe80::1dd2:bd4f:5a3:7e3  prefixlen 64  scopeid 0x20<link>
        unspec 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00  txqueuelen 100  (UNSPEC)
        RX packets 1733  bytes 450550 (439.9 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 1413  bytes 143366 (140.0 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
wlan0: flags=4099<UP,BROADCAST,MULTICAST>  mtu 1500
        ether b8:27:eb:70:4d:4d  txqueuelen 1000  (Ethernet)
        RX packets 0  bytes 0 (0.0 B)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 0  bytes 0 (0.0 B)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

this is the firewall configuration:

Chain PREROUTING (policy ACCEPT 466K packets, 81M bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain INPUT (policy ACCEPT 420K packets, 79M bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain OUTPUT (policy ACCEPT 563K packets, 42M bytes)
 pkts bytes target     prot opt in     out     source               destination         
 5298  318K DOCKER     all  --  *      *       0.0.0.0/0           !127.0.0.0/8          ADDRTYPE match dst-type LOCAL

Chain POSTROUTING (policy ACCEPT 563K packets, 42M bytes)
 pkts bytes target     prot opt in     out     source               destination         
 2215  200K SNAT       all  --  *      tun57   192.168.55.0/24      0.0.0.0/0            to:192.168.57.2

this is my openvpn client configuration:

client
dev tun57
proto udp
remote xxxxxxxxx 119x
resolv-retry infinite
nobind
persist-key
persist-tun
ca xx_xx.crt
cert xxxxxxxxx.crt
key xxxxxxxxx.key
ns-cert-type server
comp-lzo
verb 3

than you.

24

Run the same on 55.4

I suppose 57.4 is the server on the other side and tcp/2812 is the application port.

25

This is the result

0 packets captured
0 packets received by filter
0 packets dropped by kernel

I don't know why.

26

You said that ping is working with the redirection.
Start a ping on a host on the .55. network and capture this on both routers:
tcpdump -i any -vn icmp and (host 192.168.55.XX or host 192.168.57.YY)
Fill the XX and YY accordingly.

27

Yes, with ping from my laptot to 57.4 I have:

on Openwrt router:

18:34:41.521659 IP (tos 0x0, ttl 128, id 43119, offset 0, flags [none], proto ICMP (1), length 60)
    192.168.55.31 > 192.168.57.4: ICMP echo request, id 1, seq 4216, length 40
18:34:41.521659 IP (tos 0x0, ttl 128, id 43119, offset 0, flags [none], proto ICMP (1), length 60)
    192.168.55.31 > 192.168.57.4: ICMP echo request, id 1, seq 4216, length 40
18:34:41.533875 IP (tos 0x0, ttl 127, id 43119, offset 0, flags [none], proto ICMP (1), length 60)
    192.168.55.31 > 192.168.57.4: ICMP echo request, id 1, seq 4216, length 40
18:34:41.539358 IP (tos 0x0, ttl 127, id 43119, offset 0, flags [none], proto ICMP (1), length 60)
    192.168.55.31 > 192.168.57.4: ICMP echo request, id 1, seq 4216, length 40

On 55.4:

18:34:41.543526 IP (tos 0x0, ttl 127, id 43119, offset 0, flags [none], proto ICMP (1), length 60)
    192.168.55.31 > 192.168.57.4: ICMP echo request, id 1, seq 4216, length 40
18:34:41.558669 IP (tos 0x0, ttl 63, id 49998, offset 0, flags [none], proto ICMP (1), length 60)
    192.168.57.4 > 192.168.55.31: ICMP echo reply, id 1, seq 4216, length 40

Thank you for your patience.

28

This is all too weird.
I have the impression that there is some policy that is not letting the packet go to the tunnel interface.
On 55.1 run
tcpdump -i any -tven tcp port 2812 or udp port 119X
On 55.4 run
tcpdump -i any -tven tcp port 2812 or udp port 119X
There will be mac addresses captured too. I want you to verify the source and destination mac for the sequence of packets. That means that the first packet will go from host to 55.1, then from 55.1 to 55.4 etc
Also one more thing, what is the router model and OpenWrt version?

29

Hi, thank you for your response.

On 55.1 I have:

 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 68: (tos 0x0, ttl 128, id 52329, offset 0, flags [DF], proto TCP (6), length 52)
    192.168.55.31.50812 > 192.168.57.4.2812: Flags [S], cksum 0x4d0d (correct), seq 3756557372, win 64240, options [mss 1460,nop,wscale 8,nop,nop,sackOK], length 0
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 68: (tos 0x0, ttl 128, id 52329, offset 0, flags [DF], proto TCP (6), length 52)
    192.168.55.31.50812 > 192.168.57.4.2812: Flags [S], cksum 0x4d0d (correct), seq 3756557372, win 64240, options [mss 1460,nop,wscale 8,nop,nop,sackOK], length 0
Out a4:91:b1:2d:45:7a ethertype IPv4 (0x0800), length 68: (tos 0x0, ttl 127, id 52329, offset 0, flags [DF], proto TCP (6), length 52)
    192.168.55.31.50812 > 192.168.57.4.2812: Flags [S], cksum 0x4d0d (correct), seq 3756557372, win 64240, options [mss 1460,nop,wscale 8,nop,nop,sackOK], length 0
Out a4:91:b1:2d:45:7a ethertype IPv4 (0x0800), length 68: (tos 0x0, ttl 127, id 52329, offset 0, flags [DF], proto TCP (6), length 52)
    192.168.55.31.50812 > 192.168.57.4.2812: Flags [S], cksum 0x4d0d (correct), seq 3756557372, win 64240, options [mss 1460,nop,wscale 8,nop,nop,sackOK], length 0
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 68: (tos 0x0, ttl 128, id 52330, offset 0, flags [DF], proto TCP (6), length 52)
    192.168.55.31.50813 > 192.168.57.4.2812: Flags [S], cksum 0x360d (correct), seq 3403919424, win 64240, options [mss 1460,nop,wscale 8,nop,nop,sackOK], length 0
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 68: (tos 0x0, ttl 128, id 52330, offset 0, flags [DF], proto TCP (6), length 52)
    192.168.55.31.50813 > 192.168.57.4.2812: Flags [S], cksum 0x360d (correct), seq 3403919424, win 64240, options [mss 1460,nop,wscale 8,nop,nop,sackOK], length 0
Out a4:91:b1:2d:45:7a ethertype IPv4 (0x0800), length 68: (tos 0x0, ttl 127, id 52330, offset 0, flags [DF], proto TCP (6), length 52)
    192.168.55.31.50813 > 192.168.57.4.2812: Flags [S], cksum 0x360d (correct), seq 3403919424, win 64240, options [mss 1460,nop,wscale 8,nop,nop,sackOK], length 0
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 62: (tos 0x0, ttl 128, id 52331, offset 0, flags [DF], proto TCP (6), length 40)
    192.168.55.31.50812 > 192.168.57.4.2812: Flags [.], cksum 0xaa7c (correct), ack 4157531251, win 514, length 0
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 62: (tos 0x0, ttl 128, id 52331, offset 0, flags [DF], proto TCP (6), length 40)
    192.168.55.31.50812 > 192.168.57.4.2812: Flags [.], cksum 0xaa7c (correct), ack 1, win 514, length 0
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 521: (tos 0x0, ttl 128, id 52332, offset 0, flags [DF], proto TCP (6), length 505)
    192.168.55.31.50812 > 192.168.57.4.2812: Flags [P.], cksum 0x8431 (correct), seq 0:465, ack 1, win 514, length 465
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 521: (tos 0x0, ttl 128, id 52332, offset 0, flags [DF], proto TCP (6), length 505)
    192.168.55.31.50812 > 192.168.57.4.2812: Flags [P.], cksum 0x8431 (correct), seq 0:465, ack 1, win 514, length 465
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 62: (tos 0x0, ttl 128, id 52333, offset 0, flags [DF], proto TCP (6), length 40)
    192.168.55.31.50813 > 192.168.57.4.2812: Flags [.], cksum 0x9e44 (correct), ack 3123517261, win 514, length 0
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 62: (tos 0x0, ttl 128, id 52333, offset 0, flags [DF], proto TCP (6), length 40)
    192.168.55.31.50813 > 192.168.57.4.2812: Flags [.], cksum 0x9e44 (correct), ack 1, win 514, length 0
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 521: (tos 0x0, ttl 128, id 52334, offset 0, flags [DF], proto TCP (6), length 505)
    192.168.55.31.50812 > 192.168.57.4.2812: Flags [P.], cksum 0x8431 (correct), seq 0:465, ack 1, win 514, length 465
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 521: (tos 0x0, ttl 128, id 52334, offset 0, flags [DF], proto TCP (6), length 505)
    192.168.55.31.50812 > 192.168.57.4.2812: Flags [P.], cksum 0x8431 (correct), seq 0:465, ack 1, win 514, length 465
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 521: (tos 0x0, ttl 128, id 52335, offset 0, flags [DF], proto TCP (6), length 505)
    192.168.55.31.50812 > 192.168.57.4.2812: Flags [P.], cksum 0x8431 (correct), seq 0:465, ack 1, win 514, length 465
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 521: (tos 0x0, ttl 128, id 52335, offset 0, flags [DF], proto TCP (6), length 505)
    192.168.55.31.50812 > 192.168.57.4.2812: Flags [P.], cksum 0x8431 (correct), seq 0:465, ack 1, win 514, length 465
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 68: (tos 0x0, ttl 128, id 52336, offset 0, flags [DF], proto TCP (6), length 52)
    192.168.55.31.50813 > 192.168.57.4.2812: Flags [.], cksum 0xc538 (correct), ack 1, win 514, options [nop,nop,sack 1 {0:1}], length 0
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 68: (tos 0x0, ttl 128, id 52336, offset 0, flags [DF], proto TCP (6), length 52)
    192.168.55.31.50813 > 192.168.57.4.2812: Flags [.], cksum 0xc538 (correct), ack 1, win 514, options [nop,nop,sack 1 {0:1}], length 0
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 68: (tos 0x0, ttl 128, id 52337, offset 0, flags [DF], proto TCP (6), length 52)
    192.168.55.31.50812 > 192.168.57.4.2812: Flags [.], cksum 0xba0f (correct), ack 1, win 514, options [nop,nop,sack 1 {0:1}], length 0
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 68: (tos 0x0, ttl 128, id 52337, offset 0, flags [DF], proto TCP (6), length 52)
    192.168.55.31.50812 > 192.168.57.4.2812: Flags [.], cksum 0xba0f (correct), ack 1, win 514, options [nop,nop,sack 1 {0:1}], length 0
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 521: (tos 0x0, ttl 128, id 52338, offset 0, flags [DF], proto TCP (6), length 505)
    192.168.55.31.50812 > 192.168.57.4.2812: Flags [P.], cksum 0x8431 (correct), seq 0:465, ack 1, win 514, length 465
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 521: (tos 0x0, ttl 128, id 52338, offset 0, flags [DF], proto TCP (6), length 505)
    192.168.55.31.50812 > 192.168.57.4.2812: Flags [P.], cksum 0x8431 (correct), seq 0:465, ack 1, win 514, length 465
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 521: (tos 0x0, ttl 128, id 52339, offset 0, flags [none], proto TCP (6), length 505)
    192.168.55.31.50812 > 192.168.57.4.2812: Flags [P.], cksum 0x8431 (correct), seq 0:465, ack 1, win 514, length 465
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 521: (tos 0x0, ttl 128, id 52339, offset 0, flags [none], proto TCP (6), length 505)
    192.168.55.31.50812 > 192.168.57.4.2812: Flags [P.], cksum 0x8431 (correct), seq 0:465, ack 1, win 514, length 465
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 68: (tos 0x0, ttl 128, id 52340, offset 0, flags [none], proto TCP (6), length 52)
    192.168.55.31.50812 > 192.168.57.4.2812: Flags [.], cksum 0xba0f (correct), ack 1, win 514, options [nop,nop,sack 1 {0:1}], length 0
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 68: (tos 0x0, ttl 128, id 52340, offset 0, flags [none], proto TCP (6), length 52)
    192.168.55.31.50812 > 192.168.57.4.2812: Flags [.], cksum 0xba0f (correct), ack 1, win 514, options [nop,nop,sack 1 {0:1}], length 0
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 68: (tos 0x0, ttl 128, id 52341, offset 0, flags [DF], proto TCP (6), length 52)
    192.168.55.31.50813 > 192.168.57.4.2812: Flags [.], cksum 0xc538 (correct), ack 1, win 514, options [nop,nop,sack 1 {0:1}], length 0
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 68: (tos 0x0, ttl 128, id 52341, offset 0, flags [DF], proto TCP (6), length 52)
    192.168.55.31.50813 > 192.168.57.4.2812: Flags [.], cksum 0xc538 (correct), ack 1, win 514, options [nop,nop,sack 1 {0:1}], length 0
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 521: (tos 0x0, ttl 128, id 52342, offset 0, flags [none], proto TCP (6), length 505)
    192.168.55.31.50812 > 192.168.57.4.2812: Flags [P.], cksum 0x8431 (correct), seq 0:465, ack 1, win 514, length 465
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 521: (tos 0x0, ttl 128, id 52342, offset 0, flags [none], proto TCP (6), length 505)
    192.168.55.31.50812 > 192.168.57.4.2812: Flags [P.], cksum 0x8431 (correct), seq 0:465, ack 1, win 514, length 465
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 62: (tos 0x0, ttl 128, id 52343, offset 0, flags [none], proto TCP (6), length 40)
    192.168.55.31.50812 > 192.168.57.4.2812: Flags [F.], cksum 0xa8aa (correct), seq 465, ack 1, win 514, length 0
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 62: (tos 0x0, ttl 128, id 52343, offset 0, flags [none], proto TCP (6), length 40)
    192.168.55.31.50812 > 192.168.57.4.2812: Flags [F.], cksum 0xa8aa (correct), seq 465, ack 1, win 514, length 0
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 502: (tos 0x0, ttl 128, id 52344, offset 0, flags [DF], proto TCP (6), length 486)
    192.168.55.31.50813 > 192.168.57.4.2812: Flags [P.], cksum 0x2219 (correct), seq 0:446, ack 1, win 514, length 446
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 502: (tos 0x0, ttl 128, id 52344, offset 0, flags [DF], proto TCP (6), length 486)
    192.168.55.31.50813 > 192.168.57.4.2812: Flags [P.], cksum 0x2219 (correct), seq 0:446, ack 1, win 514, length 446
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 502: (tos 0x0, ttl 128, id 52345, offset 0, flags [DF], proto TCP (6), length 486)
    192.168.55.31.50813 > 192.168.57.4.2812: Flags [P.], cksum 0x2219 (correct), seq 0:446, ack 1, win 514, length 446
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 502: (tos 0x0, ttl 128, id 52345, offset 0, flags [DF], proto TCP (6), length 486)
    192.168.55.31.50813 > 192.168.57.4.2812: Flags [P.], cksum 0x2219 (correct), seq 0:446, ack 1, win 514, length 446
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 502: (tos 0x0, ttl 128, id 52346, offset 0, flags [DF], proto TCP (6), length 486)
    192.168.55.31.50813 > 192.168.57.4.2812: Flags [P.], cksum 0x2219 (correct), seq 0:446, ack 1, win 514, length 446
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 502: (tos 0x0, ttl 128, id 52346, offset 0, flags [DF], proto TCP (6), length 486)
    192.168.55.31.50813 > 192.168.57.4.2812: Flags [P.], cksum 0x2219 (correct), seq 0:446, ack 1, win 514, length 446
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 521: (tos 0x0, ttl 128, id 52347, offset 0, flags [DF], proto TCP (6), length 505)
    192.168.55.31.50812 > 192.168.57.4.2812: Flags [FP.], cksum 0x8430 (correct), seq 0:465, ack 1, win 514, length 465
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 521: (tos 0x0, ttl 128, id 52347, offset 0, flags [DF], proto TCP (6), length 505)
    192.168.55.31.50812 > 192.168.57.4.2812: Flags [FP.], cksum 0x8430 (correct), seq 0:465, ack 1, win 514, length 465
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 502: (tos 0x0, ttl 128, id 52348, offset 0, flags [DF], proto TCP (6), length 486)
    192.168.55.31.50813 > 192.168.57.4.2812: Flags [P.], cksum 0x2219 (correct), seq 0:446, ack 1, win 514, length 446
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 502: (tos 0x0, ttl 128, id 52348, offset 0, flags [DF], proto TCP (6), length 486)
    192.168.55.31.50813 > 192.168.57.4.2812: Flags [P.], cksum 0x2219 (correct), seq 0:446, ack 1, win 514, length 446
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 62: (tos 0x0, ttl 128, id 52349, offset 0, flags [DF], proto TCP (6), length 40)
    192.168.55.31.50813 > 192.168.57.4.2812: Flags [F.], cksum 0x9c85 (correct), seq 446, ack 1, win 514, length 0
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 62: (tos 0x0, ttl 128, id 52349, offset 0, flags [DF], proto TCP (6), length 40)
    192.168.55.31.50813 > 192.168.57.4.2812: Flags [F.], cksum 0x9c85 (correct), seq 446, ack 1, win 514, length 0
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 502: (tos 0x0, ttl 128, id 52350, offset 0, flags [DF], proto TCP (6), length 486)
    192.168.55.31.50813 > 192.168.57.4.2812: Flags [FP.], cksum 0x2218 (correct), seq 0:446, ack 1, win 514, length 446
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 502: (tos 0x0, ttl 128, id 52350, offset 0, flags [DF], proto TCP (6), length 486)
    192.168.55.31.50813 > 192.168.57.4.2812: Flags [FP.], cksum 0x2218 (correct), seq 0:446, ack 1, win 514, length 446
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 521: (tos 0x0, ttl 128, id 52351, offset 0, flags [DF], proto TCP (6), length 505)
    192.168.55.31.50812 > 192.168.57.4.2812: Flags [FP.], cksum 0x8430 (correct), seq 0:465, ack 1, win 514, length 465
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 521: (tos 0x0, ttl 128, id 52351, offset 0, flags [DF], proto TCP (6), length 505)
    192.168.55.31.50812 > 192.168.57.4.2812: Flags [FP.], cksum 0x8430 (correct), seq 0:465, ack 1, win 514, length 465
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 68: (tos 0x0, ttl 128, id 52352, offset 0, flags [DF], proto TCP (6), length 52)
    192.168.55.31.50813 > 192.168.57.4.2812: Flags [.], cksum 0xc379 (correct), ack 1, win 514, options [nop,nop,sack 1 {0:1}], length 0
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 68: (tos 0x0, ttl 128, id 52352, offset 0, flags [DF], proto TCP (6), length 52)
    192.168.55.31.50813 > 192.168.57.4.2812: Flags [.], cksum 0xc379 (correct), ack 1, win 514, options [nop,nop,sack 1 {0:1}], length 0
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 68: (tos 0x0, ttl 128, id 52353, offset 0, flags [DF], proto TCP (6), length 52)
    192.168.55.31.50812 > 192.168.57.4.2812: Flags [.], cksum 0xba0e (correct), ack 1, win 514, options [nop,nop,sack 1 {0:1}], length 0
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 68: (tos 0x0, ttl 128, id 52353, offset 0, flags [DF], proto TCP (6), length 52)
    192.168.55.31.50812 > 192.168.57.4.2812: Flags [.], cksum 0xba0e (correct), ack 1, win 514, options [nop,nop,sack 1 {0:1}], length 0
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 502: (tos 0x0, ttl 128, id 52354, offset 0, flags [DF], proto TCP (6), length 486)
    192.168.55.31.50813 > 192.168.57.4.2812: Flags [FP.], cksum 0x2218 (correct), seq 0:446, ack 1, win 514, length 446
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 502: (tos 0x0, ttl 128, id 52354, offset 0, flags [DF], proto TCP (6), length 486)
    192.168.55.31.50813 > 192.168.57.4.2812: Flags [FP.], cksum 0x2218 (correct), seq 0:446, ack 1, win 514, length 446
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 521: (tos 0x0, ttl 128, id 52355, offset 0, flags [DF], proto TCP (6), length 505)
    192.168.55.31.50812 > 192.168.57.4.2812: Flags [FP.], cksum 0x8430 (correct), seq 0:465, ack 1, win 514, length 465
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 521: (tos 0x0, ttl 128, id 52355, offset 0, flags [DF], proto TCP (6), length 505)
    192.168.55.31.50812 > 192.168.57.4.2812: Flags [FP.], cksum 0x8430 (correct), seq 0:465, ack 1, win 514, length 465
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 502: (tos 0x0, ttl 128, id 52356, offset 0, flags [DF], proto TCP (6), length 486)
    192.168.55.31.50813 > 192.168.57.4.2812: Flags [FP.], cksum 0x2218 (correct), seq 0:446, ack 1, win 514, length 446
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 502: (tos 0x0, ttl 128, id 52356, offset 0, flags [DF], proto TCP (6), length 486)
    192.168.55.31.50813 > 192.168.57.4.2812: Flags [FP.], cksum 0x2218 (correct), seq 0:446, ack 1, win 514, length 446
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 68: (tos 0x0, ttl 128, id 52357, offset 0, flags [DF], proto TCP (6), length 52)
    192.168.55.31.50812 > 192.168.57.4.2812: Flags [.], cksum 0xba0e (correct), ack 1, win 514, options [nop,nop,sack 1 {0:1}], length 0
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 68: (tos 0x0, ttl 128, id 52357, offset 0, flags [DF], proto TCP (6), length 52)
    192.168.55.31.50812 > 192.168.57.4.2812: Flags [.], cksum 0xba0e (correct), ack 1, win 514, options [nop,nop,sack 1 {0:1}], length 0
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 68: (tos 0x0, ttl 128, id 52358, offset 0, flags [DF], proto TCP (6), length 52)
    192.168.55.31.50813 > 192.168.57.4.2812: Flags [.], cksum 0xc379 (correct), ack 1, win 514, options [nop,nop,sack 1 {0:1}], length 0
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 68: (tos 0x0, ttl 128, id 52358, offset 0, flags [DF], proto TCP (6), length 52)
    192.168.55.31.50813 > 192.168.57.4.2812: Flags [.], cksum 0xc379 (correct), ack 1, win 514, options [nop,nop,sack 1 {0:1}], length 0
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 62: (tos 0x0, ttl 128, id 52359, offset 0, flags [DF], proto TCP (6), length 40)
    192.168.55.31.50812 > 192.168.57.4.2812: Flags [R.], cksum 0xaaa8 (correct), seq 466, ack 1, win 0, length 0
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 62: (tos 0x0, ttl 128, id 52359, offset 0, flags [DF], proto TCP (6), length 40)
    192.168.55.31.50812 > 192.168.57.4.2812: Flags [R.], cksum 0xaaa8 (correct), seq 466, ack 1, win 0, length 0
Out a4:91:b1:2d:45:7a ethertype IPv4 (0x0800), length 56: (tos 0x0, ttl 127, id 52359, offset 0, flags [DF], proto TCP (6), length 40)
    192.168.55.31.50812 > 192.168.57.4.2812: Flags [R.], cksum 0xaaa8 (correct), seq 466, ack 1, win 0, length 0
Out a4:91:b1:2d:45:7a ethertype IPv4 (0x0800), length 56: (tos 0x0, ttl 127, id 52359, offset 0, flags [DF], proto TCP (6), length 40)
    192.168.55.31.50812 > 192.168.57.4.2812: Flags [R.], cksum 0xaaa8 (correct), seq 466, ack 1, win 0, length 0
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 62: (tos 0x0, ttl 128, id 52360, offset 0, flags [DF], proto TCP (6), length 40)
    192.168.55.31.50813 > 192.168.57.4.2812: Flags [R.], cksum 0x9e83 (correct), seq 447, ack 1, win 0, length 0
 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 62: (tos 0x0, ttl 128, id 52360, offset 0, flags [DF], proto TCP (6), length 40)
    192.168.55.31.50813 > 192.168.57.4.2812: Flags [R.], cksum 0x9e83 (correct), seq 447, ack 1, win 0, length 0
Out a4:91:b1:2d:45:7a ethertype IPv4 (0x0800), length 56: (tos 0x0, ttl 127, id 52360, offset 0, flags [DF], proto TCP (6), length 40)
    192.168.55.31.50813 > 192.168.57.4.2812: Flags [R.], cksum 0x9e83 (correct), seq 447, ack 1, win 0, length 0
Out a4:91:b1:2d:45:7a ethertype IPv4 (0x0800), length 56: (tos 0x0, ttl 127, id 52360, offset 0, flags [DF], proto TCP (6), length 40)
    192.168.55.31.50813 > 192.168.57.4.2812: Flags [R.], cksum 0x9e83 (correct), seq 447, ack 1, win 0, length 0
^C
71 packets captured
72 packets received by filter
1 packet dropped by kernel

On 55.4 I have:

 In a4:91:b1:2d:45:7a ethertype IPv4 (0x0800), length 85: (tos 0x0, ttl 60, id 16565, offset 0, flags [DF], proto UDP (17), length 69)
    XXX.XXX.XXX.XXX.1196 > 192.168.55.4.44344: UDP, length 41
Out b8:27:eb:25:18:18 ethertype IPv4 (0x0800), length 85: (tos 0x0, ttl 64, id 2967, offset 0, flags [DF], proto UDP (17), length 69)
    192.168.55.4.44344 > XXX.XXX.XXX.XXX.1196: UDP, length 41
 In a4:91:b1:2d:45:7a ethertype IPv4 (0x0800), length 68: (tos 0x0, ttl 127, id 52329, offset 0, flags [DF], proto TCP (6), length 52)
    192.168.55.31.50812 > 192.168.57.4.2812: Flags [S], cksum 0x4d0d (correct), seq 3756557372, win 64240, options [mss 1460,nop,wscale 8,nop,nop,sackOK], length 0
Out ethertype IPv4 (0x0800), length 68: (tos 0x0, ttl 126, id 52329, offset 0, flags [DF], proto TCP (6), length 52)
    192.168.58.2.50812 > 192.168.57.4.2812: Flags [S], cksum 0x4a2a (correct), seq 3756557372, win 64240, options [mss 1460,nop,wscale 8,nop,nop,sackOK], length 0
Out b8:27:eb:25:18:18 ethertype IPv4 (0x0800), length 121: (tos 0x0, ttl 64, id 2975, offset 0, flags [DF], proto UDP (17), length 105)
    192.168.55.4.44344 > XXX.XXX.XXX.XXX.1196: UDP, length 77
 In a4:91:b1:2d:45:7a ethertype IPv4 (0x0800), length 68: (tos 0x0, ttl 127, id 52330, offset 0, flags [DF], proto TCP (6), length 52)
    192.168.55.31.50813 > 192.168.57.4.2812: Flags [S], cksum 0x360d (correct), seq 3403919424, win 64240, options [mss 1460,nop,wscale 8,nop,nop,sackOK], length 0
Out ethertype IPv4 (0x0800), length 68: (tos 0x0, ttl 126, id 52330, offset 0, flags [DF], proto TCP (6), length 52)
    192.168.58.2.50813 > 192.168.57.4.2812: Flags [S], cksum 0x332a (correct), seq 3403919424, win 64240, options [mss 1460,nop,wscale 8,nop,nop,sackOK], length 0
Out b8:27:eb:25:18:18 ethertype IPv4 (0x0800), length 121: (tos 0x0, ttl 64, id 2976, offset 0, flags [DF], proto UDP (17), length 105)
    192.168.55.4.44344 > XXX.XXX.XXX.XXX.1196: UDP, length 77
 In a4:91:b1:2d:45:7a ethertype IPv4 (0x0800), length 121: (tos 0x0, ttl 60, id 16578, offset 0, flags [DF], proto UDP (17), length 105)
    XXX.XXX.XXX.XXX.1196 > 192.168.55.4.44344: UDP, length 77
 In ethertype IPv4 (0x0800), length 68: (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 52)
    192.168.57.4.2812 > 192.168.58.2.50812: Flags [S.], cksum 0xf720 (correct), seq 4157531250, ack 3756557373, win 29200, options [mss 1357,nop,nop,sackOK,nop,wscale 6], length 0
Out b8:27:eb:25:18:18 ethertype IPv4 (0x0800), length 68: (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 52)
    192.168.57.4.2812 > 192.168.55.31.50812: Flags [S.], cksum 0xfa03 (correct), seq 4157531250, ack 3756557373, win 29200, options [mss 1357,nop,nop,sackOK,nop,wscale 6], length 0
 In a4:91:b1:2d:45:7a ethertype IPv4 (0x0800), length 121: (tos 0x0, ttl 60, id 16579, offset 0, flags [DF], proto UDP (17), length 105)
    XXX.XXX.XXX.XXX.1196 > 192.168.55.4.44344: UDP, length 77
 In ethertype IPv4 (0x0800), length 68: (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 52)
    192.168.57.4.2812 > 192.168.58.2.50813: Flags [S.], cksum 0xeae8 (correct), seq 3123517260, ack 3403919425, win 29200, options [mss 1357,nop,nop,sackOK,nop,wscale 6], length 0
Out b8:27:eb:25:18:18 ethertype IPv4 (0x0800), length 68: (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 52)
    192.168.57.4.2812 > 192.168.55.31.50813: Flags [S.], cksum 0xedcb (correct), seq 3123517260, ack 3403919425, win 29200, options [mss 1357,nop,nop,sackOK,nop,wscale 6], length 0
 In a4:91:b1:2d:45:7a ethertype IPv4 (0x0800), length 121: (tos 0x0, ttl 60, id 16665, offset 0, flags [DF], proto UDP (17), length 105)
    XXX.XXX.XXX.XXX.1196 > 192.168.55.4.44344: UDP, length 77
 In a4:91:b1:2d:45:7a ethertype IPv4 (0x0800), length 121: (tos 0x0, ttl 60, id 16666, offset 0, flags [DF], proto UDP (17), length 105)
    XXX.XXX.XXX.XXX.1196 > 192.168.55.4.44344: UDP, length 77
 In ethertype IPv4 (0x0800), length 68: (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 52)
    192.168.57.4.2812 > 192.168.58.2.50813: Flags [S.], cksum 0xeae8 (correct), seq 3123517260, ack 3403919425, win 29200, options [mss 1357,nop,nop,sackOK,nop,wscale 6], length 0
Out b8:27:eb:25:18:18 ethertype IPv4 (0x0800), length 68: (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 52)
    192.168.57.4.2812 > 192.168.55.31.50813: Flags [S.], cksum 0xedcb (correct), seq 3123517260, ack 3403919425, win 29200, options [mss 1357,nop,nop,sackOK,nop,wscale 6], length 0
 In ethertype IPv4 (0x0800), length 68: (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 52)
    192.168.57.4.2812 > 192.168.58.2.50812: Flags [S.], cksum 0xf720 (correct), seq 4157531250, ack 3756557373, win 29200, options [mss 1357,nop,nop,sackOK,nop,wscale 6], length 0
Out b8:27:eb:25:18:18 ethertype IPv4 (0x0800), length 68: (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 52)
    192.168.57.4.2812 > 192.168.55.31.50812: Flags [S.], cksum 0xfa03 (correct), seq 4157531250, ack 3756557373, win 29200, options [mss 1357,nop,nop,sackOK,nop,wscale 6], length 0
 In a4:91:b1:2d:45:7a ethertype IPv4 (0x0800), length 121: (tos 0x0, ttl 60, id 16675, offset 0, flags [DF], proto UDP (17), length 105)
    XXX.XXX.XXX.XXX.1196 > 192.168.55.4.44344: UDP, length 77
 In a4:91:b1:2d:45:7a ethertype IPv4 (0x0800), length 121: (tos 0x0, ttl 60, id 16676, offset 0, flags [DF], proto UDP (17), length 105)
    XXX.XXX.XXX.XXX.1196 > 192.168.55.4.44344: UDP, length 77
 In ethertype IPv4 (0x0800), length 68: (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 52)
    192.168.57.4.2812 > 192.168.58.2.50812: Flags [S.], cksum 0xf720 (correct), seq 4157531250, ack 3756557373, win 29200, options [mss 1357,nop,nop,sackOK,nop,wscale 6], length 0
Out b8:27:eb:25:18:18 ethertype IPv4 (0x0800), length 68: (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 52)
    192.168.57.4.2812 > 192.168.55.31.50812: Flags [S.], cksum 0xfa03 (correct), seq 4157531250, ack 3756557373, win 29200, options [mss 1357,nop,nop,sackOK,nop,wscale 6], length 0
 In ethertype IPv4 (0x0800), length 68: (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 52)
    192.168.57.4.2812 > 192.168.58.2.50813: Flags [S.], cksum 0xeae8 (correct), seq 3123517260, ack 3403919425, win 29200, options [mss 1357,nop,nop,sackOK,nop,wscale 6], length 0
Out b8:27:eb:25:18:18 ethertype IPv4 (0x0800), length 68: (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 52)
    192.168.57.4.2812 > 192.168.55.31.50813: Flags [S.], cksum 0xedcb (correct), seq 3123517260, ack 3403919425, win 29200, options [mss 1357,nop,nop,sackOK,nop,wscale 6], length 0
 In a4:91:b1:2d:45:7a ethertype IPv4 (0x0800), length 121: (tos 0x0, ttl 60, id 17055, offset 0, flags [DF], proto UDP (17), length 105)
    XXX.XXX.XXX.XXX.1196 > 192.168.55.4.44344: UDP, length 77
 In a4:91:b1:2d:45:7a ethertype IPv4 (0x0800), length 121: (tos 0x0, ttl 60, id 17056, offset 0, flags [DF], proto UDP (17), length 105)
    XXX.XXX.XXX.XXX.1196 > 192.168.55.4.44344: UDP, length 77
 In ethertype IPv4 (0x0800), length 68: (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 52)
    192.168.57.4.2812 > 192.168.58.2.50813: Flags [S.], cksum 0xeae8 (correct), seq 3123517260, ack 3403919425, win 29200, options [mss 1357,nop,nop,sackOK,nop,wscale 6], length 0
Out b8:27:eb:25:18:18 ethertype IPv4 (0x0800), length 68: (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 52)
    192.168.57.4.2812 > 192.168.55.31.50813: Flags [S.], cksum 0xedcb (correct), seq 3123517260, ack 3403919425, win 29200, options [mss 1357,nop,nop,sackOK,nop,wscale 6], length 0
 In ethertype IPv4 (0x0800), length 68: (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 52)
    192.168.57.4.2812 > 192.168.58.2.50812: Flags [S.], cksum 0xf720 (correct), seq 4157531250, ack 3756557373, win 29200, options [mss 1357,nop,nop,sackOK,nop,wscale 6], length 0
Out b8:27:eb:25:18:18 ethertype IPv4 (0x0800), length 68: (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 52)
    192.168.57.4.2812 > 192.168.55.31.50812: Flags [S.], cksum 0xfa03 (correct), seq 4157531250, ack 3756557373, win 29200, options [mss 1357,nop,nop,sackOK,nop,wscale 6], length 0
Out b8:27:eb:25:18:18 ethertype IPv4 (0x0800), length 85: (tos 0x0, ttl 64, id 3244, offset 0, flags [DF], proto UDP (17), length 69)
    192.168.55.4.44344 > XXX.XXX.XXX.XXX.1196: UDP, length 41
 In a4:91:b1:2d:45:7a ethertype IPv4 (0x0800), length 121: (tos 0x0, ttl 60, id 17451, offset 0, flags [DF], proto UDP (17), length 105)
    XXX.XXX.XXX.XXX.1196 > 192.168.55.4.44344: UDP, length 77
 In a4:91:b1:2d:45:7a ethertype IPv4 (0x0800), length 121: (tos 0x0, ttl 60, id 17452, offset 0, flags [DF], proto UDP (17), length 105)
    XXX.XXX.XXX.XXX.1196 > 192.168.55.4.44344: UDP, length 77
 In ethertype IPv4 (0x0800), length 68: (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 52)
    192.168.57.4.2812 > 192.168.58.2.50812: Flags [S.], cksum 0xf720 (correct), seq 4157531250, ack 3756557373, win 29200, options [mss 1357,nop,nop,sackOK,nop,wscale 6], length 0
Out b8:27:eb:25:18:18 ethertype IPv4 (0x0800), length 68: (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 52)
    192.168.57.4.2812 > 192.168.55.31.50812: Flags [S.], cksum 0xfa03 (correct), seq 4157531250, ack 3756557373, win 29200, options [mss 1357,nop,nop,sackOK,nop,wscale 6], length 0
 In ethertype IPv4 (0x0800), length 68: (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 52)
    192.168.57.4.2812 > 192.168.58.2.50813: Flags [S.], cksum 0xeae8 (correct), seq 3123517260, ack 3403919425, win 29200, options [mss 1357,nop,nop,sackOK,nop,wscale 6], length 0
Out b8:27:eb:25:18:18 ethertype IPv4 (0x0800), length 68: (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 52)
    192.168.57.4.2812 > 192.168.55.31.50813: Flags [S.], cksum 0xedcb (correct), seq 3123517260, ack 3403919425, win 29200, options [mss 1357,nop,nop,sackOK,nop,wscale 6], length 0
Out b8:27:eb:25:18:18 ethertype IPv4 (0x0800), length 85: (tos 0x0, ttl 64, id 3563, offset 0, flags [DF], proto UDP (17), length 69)
    192.168.55.4.44344 > XXX.XXX.XXX.XXX.1196: UDP, length 41
 In a4:91:b1:2d:45:7a ethertype IPv4 (0x0800), length 62: (tos 0x0, ttl 127, id 52359, offset 0, flags [DF], proto TCP (6), length 40)
    192.168.55.31.50812 > 192.168.57.4.2812: Flags [R.], cksum 0xaaa8 (correct), seq 467, ack 1, win 0, length 0
Out ethertype IPv4 (0x0800), length 56: (tos 0x0, ttl 126, id 52359, offset 0, flags [DF], proto TCP (6), length 40)
    192.168.58.2.50812 > 192.168.57.4.2812: Flags [R.], cksum 0xa7c5 (correct), seq 467, ack 1, win 0, length 0
Out b8:27:eb:25:18:18 ethertype IPv4 (0x0800), length 109: (tos 0x0, ttl 64, id 3625, offset 0, flags [DF], proto UDP (17), length 93)
    192.168.55.4.44344 > XXX.XXX.XXX.XXX.1196: UDP, length 65
 In a4:91:b1:2d:45:7a ethertype IPv4 (0x0800), length 62: (tos 0x0, ttl 127, id 52360, offset 0, flags [DF], proto TCP (6), length 40)
    192.168.55.31.50813 > 192.168.57.4.2812: Flags [R.], cksum 0x9e83 (correct), seq 448, ack 1, win 0, length 0
Out ethertype IPv4 (0x0800), length 56: (tos 0x0, ttl 126, id 52360, offset 0, flags [DF], proto TCP (6), length 40)
    192.168.58.2.50813 > 192.168.57.4.2812: Flags [R.], cksum 0x9ba0 (correct), seq 448, ack 1, win 0, length 0
Out b8:27:eb:25:18:18 ethertype IPv4 (0x0800), length 109: (tos 0x0, ttl 64, id 3724, offset 0, flags [DF], proto UDP (17), length 93)
    192.168.55.4.44344 > XXX.XXX.XXX.XXX.1196: UDP, length 65
 In a4:91:b1:2d:45:7a ethertype IPv4 (0x0800), length 85: (tos 0x0, ttl 60, id 18518, offset 0, flags [DF], proto UDP (17), length 69)
    XXX.XXX.XXX.XXX.1196 > 192.168.55.4.44344: UDP, length 41
Out b8:27:eb:25:18:18 ethertype IPv4 (0x0800), length 85: (tos 0x0, ttl 64, id 3994, offset 0, flags [DF], proto UDP (17), length 69)
    192.168.55.4.44344 > XXX.XXX.XXX.XXX.1196: UDP, length 41
 In a4:91:b1:2d:45:7a ethertype IPv4 (0x0800), length 85: (tos 0x0, ttl 60, id 18663, offset 0, flags [DF], proto UDP (17), length 69)
    XXX.XXX.XXX.XXX.1196 > 192.168.55.4.44344: UDP, length 41
Out b8:27:eb:25:18:18 ethertype IPv4 (0x0800), length 85: (tos 0x0, ttl 64, id 4561, offset 0, flags [DF], proto UDP (17), length 69)
    192.168.55.4.44344 > XXX.XXX.XXX.XXX.1196: UDP, length 41
 In a4:91:b1:2d:45:7a ethertype IPv4 (0x0800), length 85: (tos 0x0, ttl 60, id 18748, offset 0, flags [DF], proto UDP (17), length 69)
    XXX.XXX.XXX.XXX.1196 > 192.168.55.4.44344: UDP, length 41
Out b8:27:eb:25:18:18 ethertype IPv4 (0x0800), length 85: (tos 0x0, ttl 64, id 4642, offset 0, flags [DF], proto UDP (17), length 69)
    192.168.55.4.44344 > XXX.XXX.XXX.XXX.1196: UDP, length 41

69 packets captured
69 packets received by filter
0 packets dropped by kernel

I have a Technicolor DGA4132 running

Product: vbnt-s_ti
Release: Cobalt (18.3.k)
Version: 18.3.k.0451-3161011-20191025181819-3f83315f6d40733756f2a3ef5b192653d99f3c87k.0451-3160000-20191016150850-3f83315f6d40733756f2a3ef5b192653d99f3c87
30

First of all this Technicolor model is not in the list of supported devices.
Second this release doesn't look like OpenWrt to me, maybe some fork from another company.
Third I can see some replies in the second capture like this one

Out b8:27:eb:25:18:18 ethertype IPv4 (0x0800), length 68: (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 52)
    192.168.57.4.2812 > 192.168.55.31.50812: Flags [S.], cksum 0xfa03 (correct), seq 4157531250, ack 3756557373, win 29200, options [mss 1357,nop,nop,sackOK,nop,wscale 6], length 0

which is a SYNACK and is sent directly to 55.31 without going through 55.1
Then the 55.31 host sends the ACK

 In cc:b0:da:33:08:6b ethertype IPv4 (0x0800), length 62: (tos 0x0, ttl 128, id 52333, offset 0, flags [DF], proto TCP (6), length 40)
    192.168.55.31.50813 > 192.168.57.4.2812: Flags [.], cksum 0x9e44 (correct), ack 3123517261, win 514, length 0

which never reaches the 55.4, most likely because the firewall on 55.1 classifies it as invalid, because it has not tracked the whole tcp handshake.

You can try to disable statefull inspection for the traffic that will go tunneled, but since none of the routers is running OpenWrt, this is as much you will get from this forum.

31

Sorry but I flashed my router with Openwrt version 18.3.
I didn't understand if I have to disable statefull inspection for the traffic that will go tunneled on 55.1 or 55.4.
However, if you can't help me, thank you for the time spent so far.

32

There is no OpenWrt version 18.3

On 55.1
Or you can take @lleachii's advice and move the tunnel on 55.1