> There are ports that do this with more features, but I thought others
> might like to do it in base with no added software. I've been using this
> script since 4.2 and it works OK:
>
> #!/bin/ksh
>
> # Cron this script to run every X minutes. Written for OpenBSD.
>
> # Get Current IP
> lynx -dump
http://checkip.dyndns.org:8245/ | awk '{print }' | sed
> '/^$/d' > ip_new.txt
>
> # compare new with old
> diff ip_new.txt ip_old.txt
>
> # if different, send update
> if [ $? -ne 0 ]
> then
> #echo "The IP has changed"
> ip=$(cat ip_new.txt)
> # Following two lines are optional. Log date of change and IP history.
> date >> ip_date.txt
> cat ip_old.txt >> ip_history.txt
> curl --insecure
> "https://user:pass@members.dyndns.org/nic/update?hostname=host.xxx&myip=$ip&wildcard=NOCHG&mx=NOCHG&backmx=NOCHG"
> fi
>
> # Whether a change has occurred or not, overwrite old with new
> cp ip_new.txt ip_old.txt
