path.conf.example

# == apernet-traced path definition file =======================================
#
# in apernet-traced, you define a set of rules to match on different source and
# destination IP addresses, then define traceroute hops for them.
# 
# the rules are evaluated from top to down. if a rule matches, the remaining
# rules are ignored. if nothing matched, no reply will be sent - unless you
# define a default rule.

# this rule will match low-TTL traffic destinating 8.8.8.8/32
rule to 8.8.8.8/32 {

    # define what will be the first hop (i.e., what to reply when a TTL=1 packet
    # is received). here, the "1.1.1.1" is the IP address of this hop. 
    hop 1.1.1.1 {
        # for each hop, you may also define a MPLS label stack.

        # the first label in stack has value of 100.
        label 100 {
            # for each label, you must also set its exp, s, and ttl value.
            exp 0;
            s 0;
            ttl 1;
        }
        
        # instead of a literal label value, you may also have apernet-traced
        # generates some random values for you. the value will change with each
        # packet.
        label random_uint(100, 200) {
            exp 0; s 1;

            # random_uint works with exp/s/ttl too.
            ttl random_uint(1, 255);
        }
    }

    # if you don't want a MPLS stack, just do this:
    hop 1.0.0.1;

    # and you may even use random IP for hops! random_ip() generates random IP
    # addresses from the given range.
    hop random_ip(10.0.0.0, 10.255.255.255) {
        label random_uint(100, 200) { exp 0; s 1; ttl random_uint(1, 255); }
    }

    # just for fun, you may even use senders' IP address as one of the hops.
    hop $src {
        label random_uint(100, 200) { exp 0; s 1; ttl 1; }
    }

    # and also dst. in some software (like mtr), this will trick the software
    # into thinking that the packet has reached the destination host.
    hop $dst;
}

# you may also specify from address for rules, to match on the source IP.
rule from 103.0.0.0/8 to 9.9.9.9/32 {
    hop 2.2.2.2 {
        label 200 { exp 0; s 1; ttl 1; }
    }

    hop $dst;
}

# or, omit the the to address, so everyone from a range will match.
rule from 10.0.0.0/8 {
    hop 3.3.3.3 {
        label 300 { exp 0; s 1; ttl 1; }
    }

    hop $dst;
}

# you may also define a default rule. note that you must put default as the last
# rule, or rules that come after it will not be evaluated.
rule default {
    hop 4.4.4.4 {
        label 300 { exp 0; s 1; ttl 1; }
    }

    hop $dst;
}