nKn may have been more pessimistic than need be. He took seriously your comment that
And the redirection isn't restricted to browser. I use linux distro and do apt-get update && apt-get upgrade frequently. When the connection gets resetted the partial downloads are meant to be resumable when reconnected.
The reason why this is unlikely to be relevant is that apt-get contacts an http site, i.e. a site on port 80: this is an excerpt from my `/etc/apt/sources.list} file:
deb http://us.archive.ubuntu.com/ubuntu/ trusty main restricted
deb-src http://us.archive.ubuntu.com/ubuntu/ trusty main restricted
deb http://us.archive.ubuntu.com/ubuntu/ trusty-updates main restricted
deb-src http://us.archive.ubuntu.com/ubuntu/ trusty-updates main restricted
which shows exactly this.
This is relevant because it means not all ports and/or protocols need be intercepted by your ISP. The reason why I am saying this is that doing so is a very heavy burden on their infrastructure.
What is generally done to keep the amount of traffic to analyze manageable is to intercept DNS requests, which precede most communication attempts, for obvious reasons. Their firewall can identify DNS requests based upon either port or protocol, or, most likely, both.
There is a way to circumvent this, and it is to use dnscrypt, a very valuable tool provided by OpenDNS. The Web page has links for the Windows and MacOS versions of the package, while for Linux you will find it in your distro's repos.
The advantage of dnscrypt is that it both uses a non-standard port, and it encrypts communication with your DNS server, so that firewalls cannot identify the nature of your connection attempt. You may choose your DNS servers freely, they provide several options besides their own, OpenDNS.
This may or may not work, but it is certainly worth a try.
The reason why it might not work is that your ISP may have setup a timer, so that, if your line is quiet longer than a fixed amount of time, then all communications are blocked, irrespective of port/protocol, and whatnot. This would be a very aggressive move, but some ISPs are not
used to competent users.
What you may do in that case is to write a simple shell script, myping.sh, containing the following lines,
#!/bin/bash
ping -c1 8.8.8.8
make it executable,
chmod 755 myping.sh
and have it execute automatically every minute by adding this line
* * * * * /path/to/myping.sh
to your crontab, by means of the command:
crontab -e
This will consume a trivial amount of bandwidth, and will keep your connection alive all of the time.
