tcptraceroute

TLDR

Trace route to a host

$ tcptraceroute host

Trace to specific destination port

$ tcptraceroute host 80

Specify source port and address

$ tcptraceroute host -p 12345 -s 192.168.1.10

Set first and maximum TTL

$ tcptraceroute host -f 1 -m 30

Set wait time and queries per hop

$ tcptraceroute host -w 3 -q 3

Specify network interface

$ tcptraceroute host -i eth0

Use numeric output only

$ tcptraceroute -n host

SYNOPSIS

tcptraceroute [options] host [destinationport] [packetlength]

DESCRIPTION

tcptraceroute is a traceroute implementation using TCP packets. It can trace through firewalls that block traditional ICMP or UDP traceroute packets by using TCP SYN packets to a specified port.

PARAMETERS

-p PORT

Set local source port

-s ADDRESS

Set source IP address

-i INTERFACE

Specify network interface to use

-f TTL

Set the initial (first) TTL value

-m TTL

Set the maximum TTL value (default: 30)

-w SECONDS

Set the timeout for each probe (default: 3)

-q QUERIES

Set number of queries per hop (default: 3)

-n

Print numeric addresses only (no DNS resolution)

-N

Enable lookup of hostnames

-S

Set SYN flag on outgoing packets

-A

Set ACK flag on outgoing packets

-E

Set ECN flag on outgoing packets

CAVEATS

Requires root privileges or appropriate capabilities to send raw packets. The destination port defaults to 80 (HTTP). Some firewalls may still block TCP probes depending on their configuration.

HISTORY

tcptraceroute was created as an alternative to traditional traceroute that could bypass firewalls blocking ICMP and UDP packets by using TCP SYN packets.