Re: [Openvpn-users] OpenVPN tunnel stopped working (no traffic) after upgrade to OpenVPN 2.7 (Fedora 44)

On Thu, May 14, 2026 at 9:58 PM Antonio Quartulli <[email protected]> wrote:
>
> This looks interesting, but please don't filter for "icmp", because on
> the uplink interface you can't see what's inside the OpenVPN packets.
> So here you are filtering for "outern ICMPs".
>
> Please rather filter for "host xyz.sfx.pl" and do the test again.


[miner@hostx ~]$ sudo tcpdump -i enp5s0 host xyz.sfx.pl
dropped privs to tcpdump
tcpdump: verbose output suppressed, use -v[v]... for full protocol decode
listening on enp5s0, link-type EN10MB (Ethernet), snapshot length 262144 bytes
22:03:30.738318 IP hostx.45356 > xyz.sfx.pl.netmagic: UDP, length 96
22:03:30.738358 IP hostx.45356 > xyz.sfx.pl.netmagic: UDP, length 96
22:03:30.738509 IP hostx.45356 > xyz.sfx.pl.netmagic: UDP, length 99
22:03:30.738540 IP hostx.45356 > xyz.sfx.pl.netmagic: UDP, length 99
22:03:30.747016 IP xyz.sfx.pl.netmagic > hostx.50139: UDP, length 139
22:03:30.747019 IP xyz.sfx.pl.netmagic > hostx.50139: UDP, length 493
22:03:30.747019 IP xyz.sfx.pl.netmagic > hostx.50139: UDP, length 142
22:03:30.747019 IP xyz.sfx.pl.netmagic > hostx.50139: UDP, length 142
22:03:30.747178 IP hostx > xyz.sfx.pl: ICMP hostx udp port 50139
unreachable, length 175
22:03:30.747196 IP hostx > xyz.sfx.pl: ICMP hostx udp port 50139
unreachable, length 529
22:03:30.747203 IP hostx > xyz.sfx.pl: ICMP hostx udp port 50139
unreachable, length 178
22:03:30.747209 IP hostx > xyz.sfx.pl: ICMP hostx udp port 50139
unreachable, length 178
22:03:30.832138 IP hostx.45356 > xyz.sfx.pl.netmagic: UDP, length 107
22:03:30.838669 IP xyz.sfx.pl.netmagic > hostx.50139: UDP, length 201
22:03:30.838734 IP hostx > xyz.sfx.pl: ICMP hostx udp port 50139
unreachable, length 237
22:03:35.771887 IP hostx.45356 > xyz.sfx.pl.netmagic: UDP, length 96
22:03:35.771972 IP hostx.45356 > xyz.sfx.pl.netmagic: UDP, length 96
22:03:35.772086 IP hostx.45356 > xyz.sfx.pl.netmagic: UDP, length 88
22:03:35.772099 IP hostx.45356 > xyz.sfx.pl.netmagic: UDP, length 88
22:03:35.779617 IP xyz.sfx.pl.netmagic > hostx.50139: UDP, length 139
22:03:35.779618 IP xyz.sfx.pl.netmagic > hostx.50139: UDP, length 131
22:03:35.779657 IP hostx > xyz.sfx.pl: ICMP hostx udp port 50139
unreachable, length 175
22:03:35.779665 IP hostx > xyz.sfx.pl: ICMP hostx udp port 50139
unreachable, length 167
22:03:35.782760 IP xyz.sfx.pl.netmagic > hostx.50139: UDP, length 493
22:03:35.782761 IP xyz.sfx.pl.netmagic > hostx.50139: UDP, length 131
22:03:35.782916 IP hostx > xyz.sfx.pl: ICMP hostx udp port 50139
unreachable, length 529
22:03:35.782939 IP hostx > xyz.sfx.pl: ICMP hostx udp port 50139
unreachable, length 167
22:03:36.021811 IP hostx.45356 > xyz.sfx.pl.netmagic: UDP, length 96
22:03:36.031497 IP xyz.sfx.pl.netmagic > hostx.50139: UDP, length 190
22:03:36.031550 IP hostx > xyz.sfx.pl: ICMP hostx udp port 50139
unreachable, length 226
22:03:37.585586 IP xyz.sfx.pl.netmagic > hostx.35487: UDP, length 37
22:03:37.585637 IP hostx > xyz.sfx.pl: ICMP hostx udp port 35487
unreachable, length 73
22:03:37.705371 IP hostx.45356 > xyz.sfx.pl.netmagic: UDP, length 108
22:03:37.714416 IP xyz.sfx.pl.netmagic > hostx.50139: UDP, length 105
22:03:37.714531 IP hostx > xyz.sfx.pl: ICMP hostx udp port 50139
unreachable, length 141
22:03:38.736010 IP hostx.45356 > xyz.sfx.pl.netmagic: UDP, length 108
22:03:38.742800 IP xyz.sfx.pl.netmagic > hostx.50139: UDP, length 105
22:03:38.742835 IP hostx > xyz.sfx.pl: ICMP hostx udp port 50139
unreachable, length 141
22:03:39.760025 IP hostx.45356 > xyz.sfx.pl.netmagic: UDP, length 108
22:03:39.766470 IP xyz.sfx.pl.netmagic > hostx.45356: UDP, length 37
22:03:39.766471 IP xyz.sfx.pl.netmagic > hostx.50139: UDP, length 105
22:03:39.766495 IP hostx > xyz.sfx.pl: ICMP hostx udp port 50139
unreachable, length 141
22:03:40.784053 IP hostx.45356 > xyz.sfx.pl.netmagic: UDP, length 108
22:03:40.790414 IP xyz.sfx.pl.netmagic > hostx.50139: UDP, length 105
22:03:40.790443 IP hostx > xyz.sfx.pl: ICMP hostx udp port 50139
unreachable, length 141
22:03:41.021702 IP hostx.45356 > xyz.sfx.pl.netmagic: UDP, length 85
22:03:41.021746 IP hostx.45356 > xyz.sfx.pl.netmagic: UDP, length 85
22:03:41.021759 IP hostx.45356 > xyz.sfx.pl.netmagic: UDP, length 88
22:03:41.021769 IP hostx.45356 > xyz.sfx.pl.netmagic: UDP, length 88
22:03:41.021881 IP hostx.45356 > xyz.sfx.pl.netmagic: UDP, length 88
22:03:41.030527 IP xyz.sfx.pl.netmagic > hostx.50139: UDP, length 482
22:03:41.030527 IP xyz.sfx.pl.netmagic > hostx.50139: UDP, length 131


Regards,
Piotr Dobrogost


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