Note: Cannot set tx queue length on tun0: Operation not permitted (errno=1)

tqb

I installed Openvpn to cloud container Ubuntu (on Jelastic). Mainly, my configuration is full Ubuntu 18.04, with public ip. Then I install Openvpn.

apt install openvpn
apt install easy-rsa

I follow this step by step: https://openvpn.net/community-resources/how-to/

Keys, all possible pass, without problem.

Then I make server configuration file:
port 1194
proto udp
dev tun
---keys, pem
topology subnet
server 10.8.0.0 255.255.255.0
etc etc. Mainly: I use sample configuration file, about "without modification". Protoco udp, dev tun.

Then "openvpn server.ovpn", and result:

Fri Jul 17 10:07:05 2020 OpenVPN 2.4.4 x86_64-pc-linux-gnu [SSL (OpenSSL)] [LZO] [LZ4] [EPOLL] [PKCS11] [MH/PKTINFO] [AEAD] built on May 14 2019
Fri Jul 17 10:07:05 2020 library versions: OpenSSL 1.1.1  11 Sep 2018, LZO 2.08
Fri Jul 17 10:07:05 2020 Diffie-Hellman initialized with 2048 bit key
Fri Jul 17 10:07:05 2020 TUN/TAP device tun0 opened
Fri Jul 17 10:07:05 2020 Note: Cannot set tx queue length on tun0: Operation not permitted (errno=1)
Fri Jul 17 10:07:05 2020 do_ifconfig, tt->did_ifconfig_ipv6_setup=0
Fri Jul 17 10:07:05 2020 /sbin/ip link set dev tun0 up mtu 1500
Fri Jul 17 10:07:05 2020 /sbin/ip addr add dev tun0 10.8.0.1/24 broadcast 10.8.0.255
Fri Jul 17 10:07:05 2020 failed to find GID for group nobody
Fri Jul 17 10:07:05 2020 Exiting due to fatal error
Fri Jul 17 10:07:05 2020 Closing TUN/TAP interface
Fri Jul 17 10:07:05 2020 /sbin/ip addr del dev tun0 10.8.0.1/24

"tx queue", ipv6 etc etc.

Any idea? How I can fix this?

tqb

Configurtion file:
;local 10.80.9.195
port 1194
proto udp
dev tun

ca ca.crt
cert server.crt
key server.key
dh dh2048.pem

topology subnet
server 10.8.0.0 255.255.255.0

ifconfig-pool-persist ipp.txt

push "route 10.15.0.0 255.255.252.0"
push "route 10.16.0.0 255.255.252.0"
push "route 10.16.0.0 255.255.252.0"

;client-config-dir ccd
;route 192.168.40.128 255.255.255.248
;client-config-dir ccd
;route 10.9.0.0 255.255.255.252
;learn-address ./script
;push "redirect-gateway def1 bypass-dhcp"
;push "dhcp-option DNS 208.67.222.222"
;push "dhcp-option DNS 208.67.220.220"
client-to-client
;duplicate-cn
keepalive 10 120
;tls-auth ta.key 0
cipher AES-256-CBC
;compress lz4-v2
;push "compress lz4-v2"
;comp-lzo
;max-clients 100
user nobody
group nobody
persist-key
persist-tun
status openvpn-status.log
verb 3
mute 20
explicit-exit-notify 1

When comment away "user nobody, user nobody", result is this:

Fri Jul 17 10:42:12 2020 OpenVPN 2.4.4 x86_64-pc-linux-gnu [SSL (OpenSSL)] [LZO] [LZ4] [EPOLL] [PKCS11] [MH/PKTINFO] [AEAD] built on May 14 2019
Fri Jul 17 10:42:12 2020 library versions: OpenSSL 1.1.1  11 Sep 2018, LZO 2.08
Fri Jul 17 10:42:12 2020 Diffie-Hellman initialized with 2048 bit key
Fri Jul 17 10:42:12 2020 TUN/TAP device tun0 opened
Fri Jul 17 10:42:12 2020 Note: Cannot set tx queue length on tun0: Operation not permitted (errno=1)
Fri Jul 17 10:42:12 2020 do_ifconfig, tt->did_ifconfig_ipv6_setup=0
Fri Jul 17 10:42:12 2020 /sbin/ip link set dev tun0 up mtu 1500
Fri Jul 17 10:42:12 2020 /sbin/ip addr add dev tun0 10.8.0.1/24 broadcast 10.8.0.255
Fri Jul 17 10:42:12 2020 failed to find GID for group nobody
Fri Jul 17 10:42:12 2020 Exiting due to fatal error
Fri Jul 17 10:42:12 2020 Closing TUN/TAP interface
Fri Jul 17 10:42:12 2020 /sbin/ip addr del dev tun0 10.8.0.1/24
root@node130732-elkesan4:/etc/openvpn/easy-rsa/keys# openvpn server.ovpn 
Fri Jul 17 10:45:39 2020 OpenVPN 2.4.4 x86_64-pc-linux-gnu [SSL (OpenSSL)] [LZO] [LZ4] [EPOLL] [PKCS11] [MH/PKTINFO] [AEAD] built on May 14 2019
Fri Jul 17 10:45:39 2020 library versions: OpenSSL 1.1.1  11 Sep 2018, LZO 2.08
Fri Jul 17 10:45:39 2020 Diffie-Hellman initialized with 2048 bit key
Fri Jul 17 10:45:39 2020 TUN/TAP device tun0 opened
Fri Jul 17 10:45:39 2020 Note: Cannot set tx queue length on tun0: Operation not permitted (errno=1)
Fri Jul 17 10:45:39 2020 do_ifconfig, tt->did_ifconfig_ipv6_setup=0
Fri Jul 17 10:45:39 2020 /sbin/ip link set dev tun0 up mtu 1500
Fri Jul 17 10:45:39 2020 /sbin/ip addr add dev tun0 10.8.0.1/24 broadcast 10.8.0.255
Fri Jul 17 10:45:39 2020 Could not determine IPv4/IPv6 protocol. Using AF_INET
Fri Jul 17 10:45:39 2020 Socket Buffers: R=[212992->212992] S=[212992->212992]
Fri Jul 17 10:45:39 2020 UDPv4 link local (bound): [AF_INET][undef]:1194
Fri Jul 17 10:45:39 2020 UDPv4 link remote: [AF_UNSPEC]
Fri Jul 17 10:45:39 2020 MULTI: multi_init called, r=256 v=256
Fri Jul 17 10:45:39 2020 IFCONFIG POOL: base=10.8.0.2 size=252, ipv6=0
Fri Jul 17 10:45:39 2020 IFCONFIG POOL LIST
Fri Jul 17 10:45:39 2020 Initialization Sequence Completed

So: "cannot set tx" is not possible fix? Or, any error in my configuration?

TinCanTech

tqb wrote Fri Jul 17 10:45:39 2020 OpenVPN 2.4.4 x86_64-pc-linux-gnu [SSL (OpenSSL)] [LZO] [LZ4] [EPOLL] [PKCS11] [MH/PKTINFO] [AEAD] built on May 14 2019
Fri Jul 17 10:45:39 2020 library versions: OpenSSL 1.1.1 11 Sep 2018, LZO 2.08

Worth upgrading ..

tqb wrote Fri Jul 17 10:45:39 2020 Note: Cannot set tx queue length on tun0: Operation not permitted (errno=1)
Fri Jul 17 10:45:39 2020 do_ifconfig, tt->did_ifconfig_ipv6_setup=0
Fri Jul 17 10:45:39 2020 /sbin/ip link set dev tun0 up mtu 1500
Fri Jul 17 10:45:39 2020 /sbin/ip addr add dev tun0 10.8.0.1/24 broadcast 10.8.0.255
Fri Jul 17 10:45:39 2020 Could not determine IPv4/IPv6 protocol. Using AF_INET
Fri Jul 17 10:45:39 2020 Socket Buffers: R=[212992->212992] S=[212992->212992]
Fri Jul 17 10:45:39 2020 UDPv4 link local (bound): [AF_INET][undef]:1194
Fri Jul 17 10:45:39 2020 UDPv4 link remote: [AF_UNSPEC]
Fri Jul 17 10:45:39 2020 MULTI: multi_init called, r=256 v=256
Fri Jul 17 10:45:39 2020 IFCONFIG POOL: base=10.8.0.2 size=252, ipv6=0
Fri Jul 17 10:45:39 2020 IFCONFIG POOL LIST
Fri Jul 17 10:45:39 2020 Initialization Sequence Completed

It's only a Note and your server is up and running.

In Openvpn 2.4.4 the TX Queue length is set to 100 but in later versions the queue length is left as the operating system defualt, which is probably more than 100 anyway. The point is, you really don't need to worry about it.

This: Cannot set tx queue length on tun0: Operation not permitted (errno=1)
I cannot explain, perhaps this not even present on your Linux kernel ... ?