Traceroute

Simple traceroute program which displays possible route to a specified host, written in C. For now, two methods of tracing are implemented:

• ./traceroute -I - send ICMP echo request packets with increasing TTL value.
• ./traceroute -U - send UDP datagrams with increasing TTL value to destinations ports starting from 33434.

Usage

First, build the executable:

make

The traceroute executable will be built in the root directory of the project.

ICMP tracing

This tracing method uses raw sockets for sending ICMP echo request packets. Therefore, appropriate capabilities are needed:

sudo setcap cap_net_raw=eip traceroute

Once the capabilities are set, you can run ICMP traceroute to a specific host:

./traceroute -I example.org

Running traceroute with sudo instead of setting the capabilities is also possible.

This is the default tracing method which will be used if no explicit command line option is specified.

UDP tracing

Sending UDP datagrams does not require any additional privileges from the user. In order to run UDP version of the program, simply run:

./traceroute -U example.org

Installation

The executable can be installed to /usr/local/bin directory by executing:

make install

Command line options

• -I or -U - choose ICMP or UDP tracing method (default is ICMP).
• -n - don't resolve IP addresses to hostnames.
• -f first_ttl - TTL value to start from (default is 1)
• -m max_ttl - the maximum number of hops (default is 30).
• -q num_send - specifies how many packets will be sent for each hop (default is 3).
• -s dest_port - (UDP only) port number to start sending packets to (default is 33434). This number will be incremented after each hop.
• -w wait_time - number of seconds to wait for packets to arrive for each hop (default is 1).