From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: riccardo@rcrdbrt.com Received: from krantz.zx2c4.com (localhost [127.0.0.1]) by krantz.zx2c4.com (ZX2C4 Mail Server) with ESMTP id 2ed8c10e for ; Sat, 14 Apr 2018 07:42:11 +0000 (UTC) Received: from mail.rcrdbrt.com (rcrdbrt.com [45.32.6.71]) by krantz.zx2c4.com (ZX2C4 Mail Server) with ESMTP id caa0ce04 for ; Sat, 14 Apr 2018 07:42:11 +0000 (UTC) Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Date: Sat, 14 Apr 2018 09:56:21 +0200 From: Riccardo Berto To: "Jason A. Donenfeld" Subject: Re: Troubleshooting WireGuard connections In-Reply-To: References: <628776a245ad4895630fd727c80e8bf1@rcrdbrt.com> <33d0fd1f4c60919b98b50e2b9d04fe78@rcrdbrt.com> <2c17e7ba2590353afa04fc1619d726c2@rcrdbrt.com> Message-ID: <9896807f0c6cbee1c7c99647a3c289cc@rcrdbrt.com> Cc: WireGuard mailing list List-Id: Development discussion of WireGuard List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 2018-04-14 03:26, Jason A. Donenfeld wrote: > Hi Riccardo, > > Based on those tcpdump timestamps, it looks like the handshake > response happens nearly immediately after the handshake initiation. > Yet from your description, it appears only after many moments. In my > experience, tcpdump blocks like this when it has to do too many DNS > resolutions and the resolver is slow. You might get a more accurate > picture of what is going on if you additionally pass `-n` to tcpdump, > which should make the packets appear more instantaneously. > > Jason I used tne -n flag on tcpdump now and I'm having the exact same problem. Now DNS servers aren't involved. It worked briefly the first time I tried. I was happily getting ICMP requests and responses on the client. Then I stopped `ping 10.0.0.1` and, without touching anything, ran it again and it hung. ################# # Client output # ################# rpi3-two pi # ping 10.0.0.1 PING 10.0.0.1 (10.0.0.1) 56(84) bytes of data. ^C --- 10.0.0.1 ping statistics --- 25 packets transmitted, 0 received, 100% packet loss, time 24954ms ################# # Server output # ################# ╭─root@rcrd-online /etc/wireguard ╰─# tcpdump -vv -ni ens3 'port 51820' tcpdump: listening on ens3, link-type EN10MB (Ethernet), capture size 262144 bytes 09:49:43.996538 IP (tos 0x0, ttl 52, id 25142, offset 0, flags [none], proto UDP (17), length 176) ---.51821 > ---.51820: [udp sum ok] UDP, length 148 09:49:43.997138 IP (tos 0x88, ttl 64, id 42124, offset 0, flags [none], proto UDP (17), length 120) ---.51820 > ---.51821: [bad udp cksum 0x92e3 -> 0xb363!] UDP, length 92 09:50:00.636714 IP (tos 0x0, ttl 52, id 26161, offset 0, flags [none], proto UDP (17), length 176) ---.51821 > ---.51820: [udp sum ok] UDP, length 148 09:50:00.637240 IP (tos 0x88, ttl 64, id 48907, offset 0, flags [none], proto UDP (17), length 120) ---.51820 > ---.51821: [bad udp cksum 0x92e3 -> 0xefc7!] UDP, length 92