As an anti-harassment feature, LiveJournal account holders can choose to log the IP addresses of users who comment in their journals.
Comment IP Logging can be enabled on the Privacy tab
of the My Account Settings page using the "IP address log" option. You can choose to enable logging for all commenters
or for anonymous commenters
, or nobody
An IP address is the numerical equivalent of a domain name: the unique address of a computer connected to the internet. Many Internet service providers (ISPs) assign IP numbers on a random basis from their set of addresses upon connection; most likely, if you have a static IP address (which is always the same), you already know and may have paid a premium for that service. Domain name servers convert a domain name, such as livejournal.com, to an IP address, such as 126.96.36.199.
The IP address is not harmful, and does not point directly to the poster's home or telephone number. It will, however, allow the recipient of a comment to identify the poster's ISP. It also will identify the general location where the comment was made from the ISP's publicly available information. This location information displays on the comment, next to the IP address, on LiveJournal system and S1 styles.
There are official "whois" sites which allow you to query the IP address. To find one of these, perform a query for "whois database search" in your favorite search engine.
Please note that even if you have an anonymous commenter's IP address, it is not possible to directly determine the username of the person who posted it (assuming that they have a LiveJournal account).
The only people who can see the logged IP numbers are the owners of the journals in which the comments appear (or, if the entry is in a community, the person who posted the entry and the community's maintainers). The owner must be logged in to see the IP numbers, which appear in the header of the comment in question.
IP addresses are recorded only while logging is enabled. You cannot retroactively view IP addresses of users who left comments while logging was turned off.