By default OpenVPN sets the MTU of the tun device to 1500 (which is the same as the MTU on the ethernet devices on our machines). I'm still not sure whether fragmentation of the VPN packets is a good thing or a bad thing.
Jan 13, 2019 · So I’ve added --mssfix 1442 to my OpenVPN config and it’s working fine for the moment :) This article uses material from the Wikipedia article “Maximum transmission unit”, which is released under the Creative Commons Attribution-Share-Alike License 3.0. Tags: mtu, openvpn, vpn. Categories: dev. Updated: January 13, 2019. Share on ） ・tun-mtu等は速度にあまり影響しない（ローカル接続だから？） 検証2 インターネット接続. 測定タイミングによって速度が変わるため、定量的な測定ができなかった。 I still receive the link-mtu and tun-mtu warnings, but also securities warnings that the ciphers in the config file is 64 bits and vulnerable to attacks. So right now the configuration I provided above is better than the instructions provided by the link. Oct 03, 2018 · For this 'tun'mtu' setting the VPN throughput increases from 160 Mbps to 510 Mbps. Similarly, for the AES-256 cipher the optimal value is 24000 bytes. Explanation. By increasing the MTU size of the tun adapter and by disabling OpenVPN's internal fragmentation routines the throughput can be increased quite dramatically. The reason behind this is TUN MTU Setting set the mtu of the tunnel {1500} [tun-mtu xxx] MSS-Fix/Fragment across the tunnel set mss-fix and fragmentaion accross the tunnel. {empty} [fragment xxx] [mssfix] TLS Cipher What encryption algorithm OpenVPN should use for encrypting its control channel. {disabled} [] TLS Auth Key Solving OpenVPN MTU issues By hambier On April 4th, 2016 In Linux Introduction For some time now I’ve systematically used an OpenVPN-connection whenever I was using an untrusted WLAN (at hotels, restaurants, etc.).
TUN MTU Setting set the mtu of the tunnel {1500} [tun-mtu xxx] MSS-Fix/Fragment across the tunnel set mss-fix and fragmentaion accross the tunnel. {empty} [fragment xxx] [mssfix] TLS Cipher What encryption algorithm OpenVPN should use for encrypting its control channel. {disabled} [] TLS Auth Key
tun-mtu 1400 mssfix 1360 In the most common case, MTU on the physical interface is 1500, so it is better to set OpenVPN TUN MTU to a value lower than the real MTU, and MSSFIX to MTU-40, as in the example above. do_ifconfig (struct tuntap *tt, const char *ifname, int tun_mtu, const struct env_set *es, openvpn_net_ctx_t *ctx) do_ifconfig - configure the tunnel interface More static void HOW TO Introduction. OpenVPN is a full-featured SSL VPN which implements OSI layer 2 or 3 secure network extension using the industry standard SSL/TLS protocol, supports flexible client authentication methods based on certificates, smart cards, and/or username/password credentials, and allows user or group-specific access control policies using firewall rules applied to the VPN virtual interface.
[Openvpn-users] Link mtu warnings [Openvpn-users] Link mtu warnings. From: Alex K - 2017-09-15 16:54:52 tun-mtu 1500 fragment 1360 mssfix and on client side exactly the same: tun-mtu 1500 fragment 1360 mssfix The tun interfaces on both sides show as 1500 with ifconfig. Why is this case? I cannot recall seeing such
OpenVPN: src/openvpn/init.c Source File 2 * OpenVPN -- An application to securely tunnel IP networks 3 * over a single TCP/UDP port, with support for SSL/TLS-based 4 * session authentication and key exchange, Install and Configure OpenVPN Client on CentOS 8/Ubuntu 18 In order to connect to an OpenVPN server to allow you access your intranet local resources, you simply would need an OpenVPN client. In this guide, we are going to learn how to install and configure OpenVPN Client on CentOS 8/Ubuntu 18.04. Note that the OpenVPN software can be configured to either work as the server or the client.