Mysterious Firefox on FreeBSD with Rambler

A strange visitor comes to one of my sites several times a day from various addresses from the Rambler network, looks at one page and leaves for several hours. Moreover, in REFEREK, he has an empty request from the Rambler’s search page, he loads pictures, styles and scripts.

Who is it?

81.19.79.141 - - [08 / Feb / 2009: 09: 48: 47 +0300] "GET /info.php?id=33243 HTTP / 1.1" 200 7798 "http://www.rambler.ru/srch?words = "" Mozilla / 5.0 (X11; U; FreeBSD i386; en-US; rv: 1.8.0.9) Gecko / 20070204 Firefox / 1.5.0.9 "
81.19.79.141 - - [08 / Feb / 2009: 09: 48: 53 +0300] "GET /common.css HTTP / 1.1" 200 10208 "http://terms.monomed.ru/info.php?id=33243 "" Mozilla / 5.0 (X11; U; FreeBSD i386; en-US; rv: 1.8.0.9) Gecko / 20070204 Firefox / 1.5.0.9 "
81.19.79.141 - - [08 / Feb / 2009: 09: 48: 53 +0300] "GET /lib/jquery-1.2.6.pack.js HTTP / 1.1" 200 31033 "http://terms.monomed.ru /info.php?id=33243 "" Mozilla / 5.0 (X11; U; FreeBSD i386; en-US; rv: 1.8.0.9) Gecko / 20070204 Firefox / 1.5.0.9 "
81.19.79.141 - - [08 / Feb / 2009: 09: 48: 54 +0300] "GET /img/title_term.png HTTP / 1.1" 200 2962 "http://terms.monomed.ru/info.php?id = 33243 "" Mozilla / 5.0 (X11; U; FreeBSD i386; en-US; rv: 1.8.0.9) Gecko / 20070204 Firefox / 1.5.0.9 "
81.19.79.141 - - [08 / Feb / 2009: 09: 48: 56 +0300] "GET /favicon.ico HTTP / 1.1" 200 1150 "-" "Mozilla / 5.0 (X11; U; FreeBSD i386; en-US ; rv: 1.8.0.9) Gecko / 20070204 Firefox / 1.5.0.9 "
81.19.79.141 - - [08 / Feb / 2009: 10: 33: 11 +0300] "GET /info.php?id=9789 HTTP / 1.1" 200 10712 "http://www.rambler.ru/srch?words = "" Mozilla / 5.0 (X11; U; FreeBSD i386; en-US; rv: 1.8.0.9) Gecko / 20070204 Firefox / 1.5.0.9 "
81.19.79.141 - - [08 / Feb / 2009: 10: 33: 12 +0300] "GET /common.css HTTP / 1.1" 200 10208 "http://terms.monomed.ru/info.php?id=9789 "" Mozilla / 5.0 (X11; U; FreeBSD i386; en-US; rv: 1.8.0.9) Gecko / 20070204 Firefox / 1.5.0.9 "
81.19.79.141 - - [08 / Feb / 2009: 10: 33: 12 +0300] "GET /lib/jquery-1.2.6.pack.js HTTP / 1.1" 200 31033 "http://terms.monomed.ru /info.php?id=9789 "" Mozilla / 5.0 (X11; U; FreeBSD i386; en-US; rv: 1.8.0.9) Gecko / 20070204 Firefox / 1.5.0.9 "
81.19.79.141 - - [08 / Feb / 2009: 10: 33: 13 +0300] "GET /img/title_term.png HTTP / 1.1" 200 2962 "http://terms.monomed.ru/info.php?id = 9789 "" Mozilla / 5.0 (X11; U; FreeBSD i386; en-US; rv: 1.8.0.9) Gecko / 20070204 Firefox / 1.5.0.9 "
81.19.79.141 - - [08 / Feb / 2009: 10: 33: 17 +0300] "GET /favicon.ico HTTP / 1.1" 200 1150 "-" "Mozilla / 5.0 (X11; U; FreeBSD i386; en-US ; rv: 1.8.0.9) Gecko / 20070204 Firefox / 1.5.0.9 "
81.19.79.141 - - [08 / Feb / 2009: 11: 37: 07 +0300] "GET /info.php?id=14865 HTTP / 1.1" 200 10986 "http://www.rambler.ru/srch?words = "" Mozilla / 5.0 (X11; U; FreeBSD i386; en-US; rv: 1.8.0.9) Gecko / 20070204 Firefox / 1.5.0.9 "
81.19.79.141 - - [08 / Feb / 2009: 11: 37: 07 +0300] "GET /common.css HTTP / 1.1" 200 10208 "http://terms.monomed.ru/info.php?id=14865 "" Mozilla / 5.0 (X11; U; FreeBSD i386; en-US; rv: 1.8.0.9) Gecko / 20070204 Firefox / 1.5.0.9 "
81.19.79.141 - - [08 / Feb / 2009: 11: 37: 07 +0300] "GET /lib/jquery-1.2.6.pack.js HTTP / 1.1" 200 31033 "http://terms.monomed.ru /info.php?id=14865 "" Mozilla / 5.0 (X11; U; FreeBSD i386; en-US; rv: 1.8.0.9) Gecko / 20070204 Firefox / 1.5.0.9 "
81.19.79.141 - - [08 / Feb / 2009: 11: 37: 08 +0300] "GET /img/title_term.png HTTP / 1.1" 200 2962 "http://terms.monomed.ru/info.php?id = 14865 "" Mozilla / 5.0 (X11; U; FreeBSD i386; en-US; rv: 1.8.0.9) Gecko / 20070204 Firefox / 1.5.0.9 "
81.19.79.141 - - [08 / Feb / 2009: 11: 37: 10 +0300] "GET /favicon.ico HTTP / 1.1" 200 1150 "-" "Mozilla / 5.0 (X11; U; FreeBSD i386; en-US ; rv: 1.8.0.9) Gecko / 20070204 Firefox / 1.5.0.9 "
81.19.79.141 - - [08 / Feb / 2009: 12: 12: 14 +0300] "GET /info.php?id=42260 HTTP / 1.1" 200 14341 "http://www.rambler.ru/srch?words = "" Mozilla / 5.0 (X11; U; FreeBSD i386; en-US; rv: 1.8.0.9) Gecko / 20070204 Firefox / 1.5.0.9 "
81.19.79.141 - - [08 / Feb / 2009: 12: 12: 16 +0300] "GET /common.css HTTP / 1.1" 200 10208 "http://terms.monomed.ru/info.php?id=42260 "" Mozilla / 5.0 (X11; U; FreeBSD i386; en-US; rv: 1.8.0.9) Gecko / 20070204 Firefox / 1.5.0.9 "
81.19.79.141 - - [08 / Feb / 2009: 12: 12: 16 +0300] "GET /lib/jquery-1.2.6.pack.js HTTP / 1.1" 200 31033 "http://terms.monomed.ru /info.php?id=42260 "" Mozilla / 5.0 (X11; U; FreeBSD i386; en-US; rv: 1.8.0.9) Gecko / 20070204 Firefox / 1.5.0.9 "
81.19.79.141 - - [08 / Feb / 2009: 12: 12: 16 +0300] "GET /img/title_term.png HTTP / 1.1" 200 2962 "http://terms.monomed.ru/info.php?id = 42260 "" Mozilla / 5.0 (X11; U; FreeBSD i386; en-US; rv: 1.8.0.9) Gecko / 20070204 Firefox / 1.5.0.9 "
81.19.79.141 - - [08 / Feb / 2009: 12: 12: 18 +0300] "GET /favicon.ico HTTP / 1.1" 200 1150 "-" "Mozilla / 5.0 (X11; U; FreeBSD i386; en-US ; rv: 1.8.0.9) Gecko / 20070204 Firefox / 1.5.0.9 "