Set default IP TTL to 64 to match ubuntu

[phillip-stephens]

To ensure as accurate of a hitrate as possible, use the IPDEFTTL (64) for the TTL value in the IP header to match the IP packet header TTL used by Ubuntu.

Testing

Sent a packet without specifying the TTL

Note

Note the TTL = 64 in the first line

20:17:07.232286 IP (tos 0x0, ttl 64, id 10173, offset 0, flags [none], proto TCP (6), length 60)  171.67.71.218.46980 > 54.47.81.210.http: Flags [S], cksum 0xd772 (correct), seq 3499764253, win 65535, options [mss 1460,sackOK,TS val 1713298627 ecr 0,nop,wscale 7], length 0

Sent a packet and specified the TTL=39 with --probe-ttl=39

Note

Note the TTL = 39 in the first line

20:17:22.988555 IP (tos 0x0, ttl 39, id 57781, offset 0, flags [none], proto TCP (6), length 60)
    171.67.71.218.58600 > 173-242-34-17.cdma-pool.blue.net.http: Flags [S], cksum 0x6e86 (correct), seq 3716812964, win 65535, options [mss 1460,sackOK,TS val 1713298642 ecr 0,nop,wscale 7], length 0