The "compress" option

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OpenVpn Newbie
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Joined: Thu Dec 13, 2018 9:18 am

The "compress" option

Post by jafree » Wed Jan 09, 2019 7:44 am

I have several iOS clients that need to access my VPN. The latest iOS OpenVPN update broke them, thanks to comp-lzo being disabled.

I tried to upgrade the server but that caused problems with old (non-iOS) clients. Backwards compatibility with compress / comp-lzo is apparently a problem. Furthermore, OpenWRT doesn't seem to generate the OpenVPN configuration file correctly when you have "compress" with no parameters.

According to the manual, "compress" should be set to one of these: lzo, lz4, <empty>

I think the use of no parameter (empty) is a poor choice. It would make things much more clear in the configuration if you were supposed to put "off" as the parameter. Just seeing "compress" in the configuration doesn't intuitively tell someone that it means "compress off". It wouldn't help the backwards compatibility problems but I think it would also avoid the problem noted with OpenWRT.
OpenVpn Newbie
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Joined: Wed Mar 25, 2020 7:13 am

Re: The "compress" option

Post by » Thu Mar 26, 2020 9:23 am


compress with no parameter in the client configuration does not mean compression off. It means "ready to compress" and "waiting for the server to tell me how".
It's a fantastic way of keeping things up to date without having to maintain all clients. Imagine you have 200 clients with "compress lzo" and you want to change to "compress lz4", that means you have 200 files to change.
If you put just "compress" in the clients files then all you have to do is put "push "compress lz4" on the server side and all the clients obey and switch to lz4.


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