search

rootless-containers / slirp4netns

User-mode networking for unprivileged network namespaces
GNU General Public License v2.0
715 stars 82 forks source link

Instances aren't able to handle jumbo udp packets. #306

Closed hasan4791 closed 1 year ago

hasan4791 commented 1 year ago

When running in podman rootless mode, its observed that the UDP size of the packet being generated from the slirp4netns is above 1500MTU and those jumbo frames aren't being handled either by the network or the destination instance.

Packets with smaller sizes are working fine

16:46:50.098982 lo    In  IP fdcdafa3d2a2.51820 > fdcdafa3d2a2.36188: UDP, length 80
16:46:50.159104 lo    In  IP fdcdafa3d2a2.36188 > fdcdafa3d2a2.51820: UDP, length 80

Packets with larger size stuck one way

16:46:51.677731 lo    In  IP fdcdafa3d2a2.51820 > fdcdafa3d2a2.36188: UDP, length 2256
16:46:52.177416 lo    In  IP fdcdafa3d2a2.51820 > fdcdafa3d2a2.36188: UDP, length 4656
16:46:52.177443 lo    In  IP fdcdafa3d2a2.51820 > fdcdafa3d2a2.36188: UDP, length 4592
16:46:52.177468 lo    In  IP fdcdafa3d2a2.51820 > fdcdafa3d2a2.36188: UDP, length 4656
16:46:52.677117 lo    In  IP fdcdafa3d2a2.51820 > fdcdafa3d2a2.36188: UDP, length 4352
16:46:52.677142 lo    In  IP fdcdafa3d2a2.51820 > fdcdafa3d2a2.36188: UDP, length 2960
16:46:52.677174 lo    In  IP fdcdafa3d2a2.51820 > fdcdafa3d2a2.36188: UDP, length 4352
16:46:52.677232 lo    In  IP fdcdafa3d2a2.51820 > fdcdafa3d2a2.36188: UDP, length 3712
16:46:52.677238 lo    In  IP fdcdafa3d2a2.51820 > fdcdafa3d2a2.36188: UDP, length 4016
16:46:52.677242 lo    In  IP fdcdafa3d2a2.51820 > fdcdafa3d2a2.36188: UDP, length 3712
hasan4791 commented 1 year ago

Had to update the MTU parameter in containers.conf file which resolved this issue. 👍🏽