Freshclam with Proxy enabled over HTTP uses CONNECT instead of GET. Proxy only allows CONNECT for HTTPS

[pomverte]

trafficstars

Describe the bug

Our freshclam process is trying to updates the signature through a mirror server.

The connexion must go through a proxy

freshclam seems to make a HTTP call with the verb CONNECT on port 80

However the proxy only allow CONNECT call on port 443

┌─────────────┐                                     ┌─────────────────┐             ┌─────────────┐
│             │                                     │                 │             │             │
│  ClamAV     │  CONNECT proxy-server.org:80 HTTP   │      PROXY      │             │  Database   │
│  freshclam  ├────────────────────────────────────►│  port 443 only  ├────────────►│             │
└─────────────┘                                     └─────────────────┘             └─────────────┘

Is it possible to configure the port ?

[finchy]

What happens when you change the :80 to :443?

[pomverte]

What happens when you change the :80 to :443?

That would be awesome !

Is there a way to configure the port freshclam is making the call ?

[finchy]

To your proxy? in the FreshClam.conf file?

[val-ms]

I suppose the example config doesn't show it, but you have some options to customize the DatabaseMirror URL.

Some examples:

For a basic HTTPS connection on port 443

DatabaseMirror yourserver

For a HTTP connection on port 8000

DatabaseMirror http://yourserver:8000

For a HTTP connection on port 8000 with a subdirectory

DatabaseMirror http://yourserver:8000/somepath

But these are just for a regular mirror. You say there's a proxy between you and the mirror. FreshClam has some proxy config options as well. Some examples for how to use it can be found in the sample config: https://github.com/Cisco-Talos/clamav/blob/dev/0.104/etc/freshclam.conf.sample#L120

[arnaudmz]

Let me reprecise the observed and annoying behaviour, it is mainly due to the fact that even when trying to reach a mirror with http (not https), freshclam tries to use a CONNECT verb with the proxy, which is really uncommon : Example with an expected behaviour:

# freshclam.conf
HTTPProxyServer myproxyserver.com
HTTPProxyPort 1234
HTTPProxyUsername myusername
HTTPProxyPassword mypass

In this case freshclam will issue a CONNECT verb to the proxy in order to reach the public mirrors (on port 443 I guess), which totally makes sense.

Example with an unexpected behaviour:

# freshclam.conf
HTTPProxyServer myproxyserver.com
HTTPProxyPort 1234
HTTPProxyUsername myusername
HTTPProxyPassword mypass
PrivateMirror machine1.mylan
DatabaseMirror machine1.mylan

In this case fresh clam still issues a CONNECT verb to the proxy even when trying to reach the internal mirror (machine1.mylan) on port 80, which is very unusual.

[elelayan]

This is an issue because then the (eg. squid) proxy opens a tunnel and won't apply any more filtering once the tunnel is open. Here is the issue: https://github.com/Cisco-Talos/clamav/blob/main/libfreshclam/libfreshclam_internal.c#L706

[morph027]

I've noticed that calling freshclam -v on a shell w/ http_proxy/https_proxy environment variables works, so i've removed the HTTPProxyServer and HTTPProxyPort from the config and added a systemd dropin (/etc/systemd/system/clamav-freshclam.service.d/10-Proxy.conf):

[Service]
Environment=http_proxy=<host>:<port>
Environment=https_proxy=<host>:<port>

After systemd daemon-reload and systemd restart clamav-freshclam everything works :tada:

[ccamachofg]

Hello,

I have ran into this same issue, even when defining DatabaseMirror as http://database.clamav.net the request keeps going through the proxy using CONNECT. I think this is caused because when freshclam sees that the HTTPProxy parameters are set it applies the CURLOPT_HTTPPROXYTUNNEL option, which forces the request to be sent using tunneling (https://curl.se/libcurl/c/CURLOPT_HTTPPROXYTUNNEL.html).

So for now the only option to be able to actually cache the database files is to comment the HTTPProxy parameters from freshclam.conf and set the http_proxy and https_proxy environment variables before calling the freshclam script as @morph027 suggested