Code:
[root@contao:/var/www/html]$ tcpdump -v port 80 and src 192.168.1.3
tcpdump: listening on ens18, link-type EN10MB (Ethernet), snapshot length 262144 bytes
14:54:13.483018 IP (tos 0x0, ttl 64, id 53630, offset 0, flags [DF], proto TCP (6), length 52)
192.168.1.3.52422 > contao.http: Flags [F.], cksum 0x8385 (incorrect -> 0x2fc4), seq 2275525385, ack 3730601982, win 497, options [nop,nop,TS val 347582132 ecr 2756504530], length 0
14:54:13.483019 IP (tos 0x0, ttl 64, id 49712, offset 0, flags [DF], proto TCP (6), length 60)
192.168.1.3.35740 > contao.http: Flags [S], cksum 0x838d (incorrect -> 0x5c57), seq 365889586, win 64240, options [mss 1460,sackOK,TS val 347582132 ecr 0,nop,wscale 7], length 0
14:54:13.483266 IP (tos 0x0, ttl 64, id 49713, offset 0, flags [DF], proto TCP (6), length 52)
192.168.1.3.35740 > contao.http: Flags [.], cksum 0x8385 (incorrect -> 0x3978), ack 832703550, win 502, options [nop,nop,TS val 347582132 ecr 2756536424], length 0
14:54:13.483419 IP (tos 0x0, ttl 64, id 49714, offset 0, flags [DF], proto TCP (6), length 495)
192.168.1.3.35740 > contao.http: Flags [P.], cksum 0x8540 (incorrect -> 0x2b1d), seq 0:443, ack 1, win 502, options [nop,nop,TS val 347582132 ecr 2756536424], length 443: HTTP, length: 443
GET / HTTP/1.1
Host: 192.168.1.11
Connection: keep-alive
Cache-Control: max-age=0
Upgrade-Insecure-Requests: 1
User-Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/142.0.0.0 Safari/537.36
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.7
Accept-Encoding: gzip, deflate
Accept-Language: en-US,en;q=0.9
14:54:13.538680 IP (tos 0x0, ttl 64, id 49715, offset 0, flags [DF], proto TCP (6), length 52)
192.168.1.3.35740 > contao.http: Flags [.], cksum 0x8385 (incorrect -> 0x34a2), ack 690, win 497, options [nop,nop,TS val 347582188 ecr 2756536479], length 0
14:54:13.567322 IP (tos 0x0, ttl 64, id 49716, offset 0, flags [DF], proto TCP (6), length 52)
192.168.1.3.35740 > contao.http: Flags [.], cksum 0x8385 (incorrect -> 0x3464), ack 695, win 497, options [nop,nop,TS val 347582216 ecr 2756536508], length 0
14:54:18.614662 IP (tos 0x0, ttl 64, id 49717, offset 0, flags [DF], proto TCP (6), length 52)
192.168.1.3.35740 > contao.http: Flags [.], cksum 0x8385 (incorrect -> 0x0d1e), ack 696, win 497, options [nop,nop,TS val 347587264 ecr 2756541513], length 0
14:55:03.602673 IP (tos 0x0, ttl 64, id 49718, offset 0, flags [DF], proto TCP (6), length 52)
192.168.1.3.35740 > contao.http: Flags [.], cksum 0x8385 (incorrect -> 0x5d62), ack 696, win 497, options [nop,nop,TS val 347632252 ecr 2756541513], length 0
Die 192.168.1.3 ist die VM, von der aus ich ohne https contao aufrufe. 192.168.1.11 ist die VM auf der Contao läuft. Also es kommt etwas an, aber "cksum incorrect"..?