strange requests from Vanguard Securities: 53,137,138

In browsing vanguard.com I find it slow, also they cause unexpected logging in my /var/log/messages file. To kill these I updated itpables to open said ports.

#!/bin/sh
# /opt/sbin/ziptables.vanguard input
#

  iptables -I INPUT -j ACCEPT -s 167.206.251.0/24 -p udp \   -m multiport --ports 53,137,138
#

iptables -L

Why are they examining these ports? No one else is.

Using a Thinkpad behind a router and my own iptables firewall. Debian Test and Sid environments.

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