Most companies castrate their internet access for their employees with a firewall and proxy. Normally only port 80 and 443 are open, which means no access to the xmpp port 5222. With this instruction you can tunnel through the firewall to use special xmpp servers. The magic feature is called BOSH and some fairy dust.
First of all you need a xmpp account with the BOSH feature. Click on the BOSH-URI before you register an account. If you get a 404 error, then contact the administrator of the server or choose another server. Sometimes the administration of the servers is poor.
You can choose a server from this list:
The next thing you need is the xmpp client Gajim. Enter your login data for your account.
Select Accounts to edit the settings …
At the account configuration choose the tab connection.
Select the tab Connection and press Manage…
The default configuration is here none. Press the button manage on the right of the combo box, which is set to none to configure the BOSH connection.
Configure the BOSH settings …
In the next dialog add a new entry at the bottom. Name it your-server-name + BOSH and choose in the combo box under the name: BOSH. The BOSH-Adress must be set as shown in the table above. Try port 80 or 443.
Select the new BOSH connection.
If only the firewall was your problem, then you are finished now.
If not, you have to set the proxy, too.
There is a checkbox for HTTP-Proxy in the dialog, where you set the BOSH data. Choose this checkpox and enter the proxy data. Enter the autentification, if needed.
Setting proxy via Gajim …
If this works, then you are done.
If not, we need a special program to tunnel through the proxy called: cntlm
Install cntlm and enter your data into the cntlm.ini – see here. The default port is 3128. Set the Proxy-Adress in Gajim to 127.0.0.1 / localhost and the Proxy-Port to 3128.
Setting cntlm proxy via Gajim …
Advanced features for encryption.
Install the plugins called OTR and OMEMO via the Gajim plugin dialog.
You can find me at digitalangel (at) trashserver.net if you need help or something else …
If you know more servers with BOSH, please write a comment!