Asked by Geraldo Leinardi
Q. (i) My ISP blocks ICMP ECHO request, I can not use traceroute command, is there any way I can send traceroute using port forwarding or something like that?
(ii) What is suggested Personal Firewalls policy for home user?
A.tcptraceroute command can bypass the most common firewall filters.
Basically traceroute sends out either UDP (ports 33434 to 33523) or ICMP ECHO packets with a TTL of one, and increments the TTL until the destination has been reached. However many ISP/WSP (web hosting service providers) blocks certain UDP (even TCP) and ICMP ports for security reasons. Use tcptraceroute command to bypass the most common firewall filters. It is a traceroute implementation using TCP packets.
Task: Install tcptraceroute
You can install tcptraceroute with apt-get command:
# apt-get install tcptraceroute
$ traceroute myserver.com
And now try tcptraceroute:
$ tcptraceroute myserver.com
For real life example try:
$ traceroute pages.ebay.com
$ tcptraceroute pages.ebay.com
Default Personal Firewalls policy for home user
Full or limited Outgoing traffic:
Internet Allow full outgoing traffic or limit outgoing traffic to:
- Web service (http/https)
- DNS Email to ISP mail server
- FTP to ftp server anywhere
- SSH to ssh server anywhere
- VPN client to corporate VPN
No Incoming traffic:
Internet -> Router -> You
No incoming traffic. To be frank it is very simple to setup such firewall, just look at our previous firewall example. This is suggested policy that allows you to browse the Internet, download files via FTP, ssh to remote server or use VPN client to connects to corporate network. You do not have to run special services like an sshd server or an ftp server on your home desktop computer.
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