connection speed is limited due to error

[sohrabp72]

English Only.
When I monitor udp2raw.service and try to download a file to leech speed, I get this error which seems limits my connection speed:

Aug 09 07:51:14 Iran udp2raw_amd64[532219]: [2023-08-09 07:51:14][WARN]huge packet, data_len 2856 > 1800(max_data_len) dropped, maybe yo
u need to turn down mtu at upper level, or you may take a look at --fix-gro

[wangyu-]

use --fix-gro as the log suggested

[sohrabp72]

I used it in command but the handshake between two servers does not happen.
also I searched a lot and didn't find any doc related to --fix-gro even in the udp2raw guide on GitHub's main page.

[wangyu-]

use on both sides

[sohrabp72]

I used it on both side but nothing changed. same result. no handshake made.

[sohrabp72]

here is my config:
on the Internal server which users can connect to:

udp2raw_amd64 -c -l0.0.0.0:2880  -r[2b8c:ab54:0:11::3]:1111 -k "secret" --raw-mode faketcp -a --fix-gro

and the server which is external and the previous server connects to:

./udp2raw_amd64 -s -l[::]:1111 -r127.0.0.1:2880 -k "secret" --raw-mode faketcp -a --fix-gro

users connect to the first server using IPv4, both servers connect to each other using IPv6.
PS: Ports and IPs and Secret changed to something else.

[wangyu-]

@sohrabp72 the parameters looks good, it should have worked

sorry it doesn't work, at the moment I don't have time to debug the problem in detail

can you try if ipv4 works for you? if ipv4 works, use ipv4

[sohrabp72]

It gets banned by government but IPv6 has a range you can change whenever you want.

[edthepurple]

@sohrabp72 what kind of traffic you're trying to tunnel using udp2raw?

[sohrabp72]

Wireguard packets

[edthepurple]

Wireguard packets

Set MTU in client config to 1280

MTU=1280

you won't see the errors anymore.

[wangyu-]

hi @sohrabp72

I tested ipv6 + fix-gro with UDPping:

server:

./udp2raw -l[::]:4567 -r127.0.0.1:4000 -s -a --fix-gro
socat -v UDP-LISTEN:4000,fork PIPE

./udpping.py 10.0.0.6 3333
sudo ./udp2raw -c -r[2001:19f0:7001:x:xx:x:x]:4567 -l0.0.0.0:3333 -a --fix-gro

it works on my environment. The hanshake completes, and the UDPping works:

yancey@yancey-ubuntu:~/UDPping$ python3 ./udpping.py 127.0.0.1 3333
UDPping 127.0.0.1 via port 3333 with 64 bytes of payload
Reply from 127.0.0.1 seq=0 time=183.41 ms
Reply from 127.0.0.1 seq=1 time=173.91 ms
Reply from 127.0.0.1 seq=2 time=174.63 ms
Reply from 127.0.0.1 seq=3 time=174.37 ms
Reply from 127.0.0.1 seq=4 time=174.69 ms

I used it on both side but nothing changed. same result. no handshake made.

I wasn't able to reproduce the problem you mentioned.

[evgfilim1]

Wireguard packets

Set MTU in client config to 1280

MTU=1280

you won't see the errors anymore.

@edthepurple I set this, but I still get [WARN]huge packet, data_len 2772 > 1800(max_data_len) dropped, maybe you need to turn down mtu at upper level, or you may take a look at --fix-gro, do I really need to add this flag?