DareNET provides a user mode which allows you to hide your host/ip completely from other users.

To use it, you will need a registered DareNET account, which you can get here (for free) if you don't already have one, and authenticated to N. Once you're authed, simply use: /mode yournick +x.

Once set, you will get confirmation that your hidden host is active through a notice from the server, similar to "accountname.user.darenet is now your hidden host." Other users will see you quit and rejoin all channels you are in with your new host. We recommend you set this mode prior to joining in the channels. You can have N automatically set you +x upon authenticating to your account by enabling the AUTOHIDE option. See /msg N HELP SET AUTOHIDE for more information.

Additionally, users who use our login-on-connect feature will automatically have their host hidden upon connecting to the network. You can also customize your hidden host by choosing a custom title. Visit the custom titles page for more details.

Once you have set user mode +x, you may not deactivate it during your current IRC session. The only way to get your original host back is to quit and reconnect to IRC. Please note that if you have autohide turned on (default) you need to turn it off via /msg N SET AUTOHIDE off.
We've created an article that explains the different quit messages in detail. It can be viewed here.
A channel closure is when a network staff member sets a badchan on a particular channel, which in turn closes the channel and disables all access to it. This action is used in extreme cases where a channel has repeatedly violated network policies and rules. It is a last resort, and never done before all other means of resolving the problem have been exhausted.
A list of supported user modes can be found here.
A list of supported channel modes can be found here.

There are few different symbols you may see prefixed to channel names in a user's WHOIS. These are:

@#channel
The user has operator status in the channel.
%#channel
The user has half operator status in the channel.
+#channel
The user has voice status in the channel.
<#channel
The user is invisible in a channel with channel mode +D or +d set.
-#channel
The user has user mode +d (deaf) set, and won't receive channel messages.
!#channel
User is a 'zombie', which means the user was kicked from the channel, but the kick has not yet been acknowledged by the user's server.