diff -c /var/mw-trunk/source/checkuser/CheckUser_body.php /var/mw-trunk/modified/checkuser/CheckUser_body.php
*** /var/mw-trunk/source/checkuser/CheckUser_body.php	2011-10-12 02:16:37.000000000 +0400
--- /var/mw-trunk/modified/checkuser/CheckUser_body.php	2011-10-15 03:10:25.000000000 +0400
***************
*** 21,27 ****
  	}
  
  	public function execute( $subpage ) {
! 		global $wgRequest, $wgOut, $wgUser, $wgContLang;
  
  		$this->setHeaders();
  
--- 21,27 ----
  	}
  
  	public function execute( $subpage ) {
! 		global $wgRequest, $wgOut, $wgUser, $wgContLang, $wgCheckUserCheckUserAgents;
  
  		$this->setHeaders();
  
***************
*** 107,112 ****
--- 107,114 ----
  				$this->doIPUsersRequest( $xff, true, $reason, $period, $tag, $talkTag );
  			} elseif ( $checktype == 'subipusers' ) {
  				$this->doIPUsersRequest( $ip, false, $reason, $period, $tag, $talkTag );
+ 			} elseif ( $wgCheckUserCheckUserAgents && $checktype == 'subagents' ) {
+ 				$this->doAgentUsersRequest( $name, $reason, $period, $tag, $talkTag );
  			}
  		}
  		# Add CIDR calculation convenience form
***************
*** 146,161 ****
  	}
  
  	protected function showForm( $user, $reason, $checktype, $ip, $xff, $name, $period ) {
! 		global $wgOut, $wgUser;
  		$action = $this->getTitle()->escapeLocalUrl();
  		# Fill in requested type if it makes sense
! 		$encipusers = $encedits = $encuserips = 0;
  		if ( $checktype == 'subipusers' && ( $ip || $xff ) ) {
  			$encipusers = 1;
  		} elseif ( $checktype == 'subuserips' && $name ) {
  			$encuserips = 1;
  		} elseif ( $checktype == 'subedits' ) {
  			$encedits = 1;
  		# Defaults otherwise
  		} elseif ( $ip || $xff ) {
  			$encedits = 1;
--- 148,165 ----
  	}
  
  	protected function showForm( $user, $reason, $checktype, $ip, $xff, $name, $period ) {
! 		global $wgOut, $wgUser, $wgCheckUserCheckUserAgents;
  		$action = $this->getTitle()->escapeLocalUrl();
  		# Fill in requested type if it makes sense
! 		$encipusers = $encedits = $encagents = $encuserips = 0;
  		if ( $checktype == 'subipusers' && ( $ip || $xff ) ) {
  			$encipusers = 1;
  		} elseif ( $checktype == 'subuserips' && $name ) {
  			$encuserips = 1;
  		} elseif ( $checktype == 'subedits' ) {
  			$encedits = 1;
+ 		} elseif ( $checktype == 'subagents' ) {
+ 			$encagents = 1;
  		# Defaults otherwise
  		} elseif ( $ip || $xff ) {
  			$encedits = 1;
***************
*** 188,193 ****
--- 192,204 ----
  		$form .= '<td>' .
  			Xml::radio( 'checktype', 'subipusers', $encipusers, array( 'id' => 'subipusers' ) );
  		$form .= ' ' . Xml::label( wfMsg( 'checkuser-users' ), 'subipusers' ) . '</td>';
+ 		
+ 		if( $wgCheckUserCheckUserAgents ) {
+ 			$form .= '<td>' .
+ 				Xml::radio( 'checktype', 'subagents', $encagents, array( 'id' => 'subagents' ) );
+ 			$form .= ' ' . Xml::label( wfMsg( 'checkuser-agents' ), 'subagents' ) . '</td>';
+ 		}
+ 		
  		$form .= '</tr>';
  		$form .= Xml::closeElement( 'table' );
  		$form .= Xml::closeElement( 'td' );
***************
*** 1058,1063 ****
--- 1069,1266 ----
  				for ( $i = ( count( $users_agentsets[$name] ) - 1 ); $i >= 0; $i-- ) {
  					$agent = $users_agentsets[$name][$i];
  					$s .= '<li><i>' . htmlspecialchars( $agent ) . "</i></li>\n";
+ 				}
+ 				$s .= '</ol>';
+ 				$s .= '</li>';
+ 			}
+ 			$s .= "</ul></div>\n";
+ 			if ( $wgUser->isAllowed( 'block' ) && !$wgUser->isBlocked() ) {
+ 				$s .= "<fieldset>\n";
+ 				$s .= '<legend>' . wfMsgHtml( 'checkuser-massblock' ) . "</legend>\n";
+ 				$s .= '<p>' . wfMsgExt( 'checkuser-massblock-text', array( 'parseinline' ) ) . "</p>\n";
+ 				$s .= '<table><tr>' .
+ 					'<td>' . Xml::check( 'usetag', false, array( 'id' => 'usetag' ) ) . '</td>' .
+ 					'<td>' . Xml::label( wfMsgHtml( 'checkuser-blocktag' ), 'usetag' ) . '</td>' .
+ 					'<td>' . Xml::input( 'tag', 46, $tag, array( 'id' => 'blocktag' ) ) . '</td>' .
+ 					'</tr><tr>' .
+ 					'<td>' . Xml::check( 'usettag', false, array( 'id' => 'usettag' ) ) . '</td>' .
+ 					'<td>' . Xml::label( wfMsgHtml( 'checkuser-blocktag-talk' ), 'usettag' ) . '</td>' .
+ 					'<td>' . Xml::input( 'talktag', 46, $talkTag, array( 'id' => 'talktag' ) ) . '</td>' .
+ 					'</tr></table>';
+ 				$s .= '<p>' . wfMsgHtml( 'checkuser-reason' ) . '&#160;';
+ 				$s .= Xml::input( 'blockreason', 46, '', array( 'maxlength' => '150', 'id' => 'blockreason' ) );
+ 				$s .= '&#160;' . Xml::submitButton( wfMsgHtml( 'checkuser-massblock-commit' ),
+ 					array( 'id' => 'checkuserblocksubmit', 'name' => 'checkuserblock' ) ) . "</p>\n";
+ 				$s .= "</fieldset>\n";
+ 			}
+ 			$s .= '</form>';
+ 		}
+ 
+ 		$wgOut->addHTML( $s );
+ 	}
+ 	
+ 	protected function doAgentUsersRequest( $agent, $reason = '', $period = 0, $tag = '', $talkTag = '' ) {
+ 		global $wgUser, $wgOut, $wgLang, $wgCheckUserCheckUserAgents, $wgCheckUserCheckUserAgentsStrict;
+ 		if( !$wgCheckUserCheckUserAgents ) return false;
+ 		
+ 		$dbr = wfGetDB( DB_SLAVE );
+ 		
+ 		if( empty($agent) ) return false;
+ 
+ 		$logType = 'agentusers';
+ 
+ 		if ( !$this->addLogEntry( $logType, 'agent', $agent, $reason ) ) {
+ 			$wgOut->addHTML( '<p>' . wfMsgHtml( 'checkuser-log-fail' ) . '</p>' );
+ 		}
+ 
+ 		$time_conds = $this->getTimeConds( $period );
+ 		
+ 		$esc = mysql_real_escape_string($agent);
+ 		if( $wgCheckUserCheckUserAgentsStrict ) {
+ 			$agent_cond = "cuc_agent = '$esc'";
+ 		} else {
+ 			$agent = preg_replace("/\*/", "%", $esc);
+ 			$agent_cond = "cuc_agent LIKE '$agent'";
+ 		}
+ 		
+ 		$cu_changes = $dbr->tableName( 'cu_changes' );
+ 
+ 		if ( $period ) {
+ 			$count = $dbr->selectField( 'cu_changes', 'COUNT(*)',
+ 				array( $agent_cond, $time_conds ),
+ 				__METHOD__,
+ 				array( 'USE INDEX' => 'cuc_user_ip_time' ) );
+ 		} else {
+ 			$count = $dbr->estimateRowCount( 'cu_changes', '*',
+ 				array( $agent_cond, $time_conds ),
+ 				__METHOD__,
+ 				array( 'USE INDEX' => 'cuc_user_ip_time' ) );
+ 		}
+ 
+ 		wfSuppressWarnings();
+ 		set_time_limit( 120 );
+ 		wfRestoreWarnings();
+ 
+ 		if ( isset( $count ) && $count > 5000 ) {
+ 			$wgOut->addHTML( wfMsgExt( 'checkuser-limited', array( 'parse' ) ) );
+ 		}
+ 
+ 		global $wgMemc;
+ 
+ 		$use_index = $dbr->useIndexClause( 'cuc_user_ip_time' );
+ 		$sql = "SELECT cuc_user_text, cuc_timestamp, cuc_user, cuc_ip, cuc_agent, cuc_xff
+ 			FROM $cu_changes $use_index WHERE $agent_cond AND $time_conds
+ 			ORDER BY cuc_timestamp DESC LIMIT 5000";
+ 		$ret = $dbr->query( $sql, __METHOD__ );
+ 
+ 		$users_first = $users_last = $users_edits = $users_ids = array();
+ 		if ( !$dbr->numRows( $ret ) ) {
+ 			$s = $this->noMatchesMessage( $ip, !$xfor ) . "\n";
+ 		} else {
+ 			global $wgAuth;
+ 			while ( ( $row = $dbr->fetchObject( $ret ) ) != false ) {
+ 				if ( !array_key_exists( $row->cuc_user_text, $users_edits ) ) {
+ 					$users_last[$row->cuc_user_text] = $row->cuc_timestamp;
+ 					$users_edits[$row->cuc_user_text] = 0;
+ 					$users_ids[$row->cuc_user_text] = $row->cuc_user;
+ 					$users_infosets[$row->cuc_user_text] = array();
+ 					$users_agentsets[$row->cuc_user_text] = array();
+ 				}
+ 				$users_edits[$row->cuc_user_text] += 1;
+ 				$users_first[$row->cuc_user_text] = $row->cuc_timestamp;
+ 				
+ 				$xff = empty( $row->cuc_xff ) ? null : $row->cuc_xff;
+ 				$xff_ip_combo = array( $row->cuc_ip, $xff );
+ 				
+ 				if ( !in_array( $xff_ip_combo, $users_infosets[$row->cuc_user_text] ) ) {
+ 					$users_infosets[$row->cuc_user_text][] = $xff_ip_combo;
+ 				}
+ 				
+ 				if ( count( $users_agentsets[$row->cuc_user_text] ) < 20 ) {
+ 					if ( !in_array( $row->cuc_agent, $users_agentsets[$row->cuc_user_text] ) ) {
+ 						$users_agentsets[$row->cuc_user_text][] = $row->cuc_agent;
+ 					}
+ 				}
+ 			}
+ 			$dbr->freeResult( $ret );
+ 
+ 			$action = $this->getTitle()->escapeLocalURL( 'action=block' );
+ 			$s = "<form name='checkuserblock' id='checkuserblock' action=\"$action\" method='post'>";
+ 			$s .= '<div id="checkuserresults"><ul>';
+ 			foreach ( $users_edits as $name => $count ) {
+ 				$s .= '<li>';
+ 				$s .= Xml::check( 'users[]', false, array( 'value' => $name ) ) . '&#160;';
+ 				
+ 				$user = User::newFromName( $name, false );
+ 				
+ 				$s .= $this->sk->userLink( - 1 , $name ) . $this->sk->userToolLinks( - 1 , $name );
+ 				
+ 				$s .= ' (<a href="' . $this->getTitle()->escapeLocalURL( 'user=' . urlencode( $name ) .
+ 					'&reason=' . urlencode( $reason ) ) . '">' . wfMsgHtml( 'checkuser-check' ) . '</a>)';
+ 				
+ 				if ( $users_first[$name] == $users_last[$name] ) {
+ 					$s .= ' (' . $wgLang->timeanddate( wfTimestamp( TS_MW, $users_first[$name] ), true ) . ') ';
+ 				} else {
+ 					$s .= ' (' . $wgLang->timeanddate( wfTimestamp( TS_MW, $users_first[$name] ), true ) .
+ 					' -- ' . $wgLang->timeanddate( wfTimestamp( TS_MW, $users_last[$name] ), true ) . ') ';
+ 				}
+ 				
+ 				$s .= ' [<strong>' . $count . '</strong>]<br />';
+ 				
+ 				$ip = IP::isIPAddress( $name ) ? $name : '';
+ 				$flags = $this->userBlockFlags( $ip, $users_ids[$name], $user );
+ 				
+ 				$authUser = $wgAuth->getUserInstance( $user );
+ 				if ( $user->getId() && $authUser->getId() === 0 ) {
+ 					$flags[] = '<strong>(' . wfMsgHtml( 'checkuser-localonly' ) . ')</strong>';
+ 				}
+ 				
+ 				if ( $users_ids[$name] ) {
+ 					if ( $user->isLocked() ) {
+ 						$flags[] = '<b>(' . wfMsgHtml( 'checkuser-locked' ) . ')</b>';
+ 					}
+ 					$list = array();
+ 					foreach ( $user->getGroups() as $group ) {
+ 						$list[] = self::buildGroupLink( $group );
+ 					}
+ 					$groups = $wgLang->commaList( $list );
+ 					if ( $groups ) {
+ 						$flags[] = '<i>(' . $groups . ')</i>';
+ 					}
+ 				}
+ 				
+ 				if ( $ip ) {
+ 					$key = wfMemcKey( 'acctcreate', 'ip', $ip );
+ 					$count = intval( $wgMemc->get( $key ) );
+ 					if ( $count ) {
+ 						$flags[] = '<strong>[' . wfMsgExt( 'checkuser-accounts', 'parsemag', $wgLang->formatNum( $count ) ) . ']</strong>';
+ 					}
+ 				}
+ 				$s .= implode( ' ', $flags );
+ 				$s .= '<ol>';
+ 				
+ 				for ( $i = ( count( $users_infosets[$name] ) - 1 ); $i >= 0; $i-- ) {
+ 					$set = $users_infosets[$name][$i];
+ 					
+ 					$s .= '<li>';
+ 					$s .= '<a href="' . $this->getTitle()->escapeLocalURL( 'user=' . urlencode( $set[0] ) ) . '">' . htmlspecialchars( $set[0] ) . '</a>';
+ 					
+ 					if ( $set[1] ) {
+ 						
+ 						list( $client, $trusted ) = efGetClientIPfromXFF( $set[1], $set[0] );
+ 						$c = $trusted ? '#F0FFF0' : '#FFFFCC';
+ 						$s .= '&#160;&#160;&#160;<span style="background-color: ' . $c . '"><strong>XFF</strong>: ';
+ 						$s .= $this->sk->makeKnownLinkObj( $this->getTitle(),
+ 							htmlspecialchars( $set[1] ),
+ 							'user=' . urlencode( $client ) . '/xff' ) . '</span>';
+ 					}
+ 					$s .= "</li>\n";
+ 				}
+ 				$s .= '</ol><br /><ol>';
+ 				
+ 				for ( $i = ( count( $users_agentsets[$name] ) - 1 ); $i >= 0; $i-- ) {
+ 					$agent = $users_agentsets[$name][$i];
+ 					$s .= '<li><i>' . htmlspecialchars( $agent ) . "</i></li>\n";
  				}
  				$s .= '</ol>';
  				$s .= '</li>';
diff -c /var/mw-trunk/source/checkuser/CheckUser.i18n.php /var/mw-trunk/modified/checkuser/CheckUser.i18n.php
*** /var/mw-trunk/source/checkuser/CheckUser.i18n.php	2011-10-15 00:06:14.000000000 +0400
--- /var/mw-trunk/modified/checkuser/CheckUser.i18n.php	2011-10-15 03:07:02.000000000 +0400
***************
*** 34,39 ****
--- 34,40 ----
  	'checkuser-users'            => 'Get users',
  	'checkuser-edits'            => 'Get edits',
  	'checkuser-ips'              => 'Get IP addresses',
+ 	'checkuser-agents'           => 'Get users with User-Agent',
  	'checkuser-search'           => 'Search',
  	'checkuser-period'           => 'Duration:',
  	'checkuser-week-1'           => 'last week',
***************
*** 85,90 ****
--- 86,92 ----
  	'checkuser-log-ipedits-xff'  => '$1 got edits for XFF $2',
  	'checkuser-log-ipusers-xff'  => '$1 got users for XFF $2',
  	'checkuser-log-useredits'    => '$1 got edits for $2',
+ 	'checkuser-log-agentusers'   => '$1 got users with User-Agent "$2"',
  
  	'checkuser-autocreate-action' => 'was automatically created',
  	'checkuser-create-action' => 'was created',
diff -c /var/mw-trunk/source/checkuser/CheckUser.php /var/mw-trunk/modified/checkuser/CheckUser.php
*** /var/mw-trunk/source/checkuser/CheckUser.php	2011-07-15 04:48:02.000000000 +0400
--- /var/mw-trunk/modified/checkuser/CheckUser.php	2011-10-15 02:54:00.000000000 +0400
***************
*** 78,83 ****
--- 78,87 ----
  	'remoteExtPath' => 'CheckUser',
  );
  
+ # User-Agent checks feature
+ $wgCheckUserCheckUserAgents = false;
+ $wgCheckUserCheckUserAgentsStrict = true;
+ 
  // Set up the new special page
  $wgSpecialPages['CheckUser'] = 'CheckUser';
  $wgSpecialPageGroups['CheckUser'] = 'users';