UDP 33434
Synopsis
- UDP port 33434 is the classic starting destination port used by UDP-based traceroute.
- Unix/Linux traceroute implementations (e.g., GNU inetutils traceroute and the classic BSD traceroute) default to sending UDP probes to port 33434 and incrementing upward.
- macOS’s traceroute also uses UDP to destination port 33434 by default (with -I switching to ICMP).
- Cisco IOS/NX-OS “traceroute” uses UDP probes targeting ports 33434–33464 by default.
- Juniper Junos “traceroute” similarly uses UDP starting at 33434 unless configured for ICMP or TCP.
- MTR in UDP mode (mtr -u) and Paris Traceroute (UDP mode) send probes to 33434 and increment through a range.
- RIPE Atlas traceroute measurements commonly use UDP/33434 when configured for UDP (Paris-traceroute style).
- Network administrators often allow UDP 33434–33534 on firewalls specifically to permit traceroute from these systems.
Observed activity
Last 30 days
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