Redmine

I have quite aт overladen installation.
Ubuntu, nginx(listens 8081) + apache(8888) + redmine through passanger.
Don't ask me why. Legacy and stuff.
It even works, I can see home page at http://host:8081/redmine/
The problem is links dont't work. Though my browser shows them as http://host:8081/redmine/account/register it leads to http://host/redmine/account/register
8081 is the only port avaiable, so request to this adress doesn't even get to nginx.
Can I force the port usage somehow? Or is there any other solution?
Not a native speaker, sorry for my english.

About your application's environment
Ruby version 1.8.7 (x86_64-linux)
RubyGems version 1.8.15
Rack version 1.3
Rails version 2.3.14
Active Record version 2.3.14
Active Resource version 2.3.14
Action Mailer version 2.3.14
Active Support version 2.3.14
Edge Rails revision unknown
Application root /usr/share/redmine
Environment production
Database adapter mysql
Database schema version 20110902000000