Users cannot connect to The Ship dedicated server

I am attempting to run a dedicated server for The Ship on my Ubuntu VPS. The server seems to start and run just fine, but nobody can connect to it - any attempts simply result in a timeout.

To start the server, I used this command:

$ ./srcds_run -game ship

And this is the output: Auto detecting CPU Using SSE2 Optimised binary. Auto-restarting the server on crash

Console initialized.
Attempted to create unknown entity type event_queue_saveload_proxy!
Game.dll loaded for "The Ship"
CSoundEmitterSystem::AddSoundsFromFile:  No such file scripts/game_sounds_single_player.txt
CSoundEmitterSystem::AddSoundsFromFile:  No such file scripts/game_sounds_vo_tutorial.txt
maxplayers set to 1
Unknown command "ex/"
Unknown command "yautoexec.cfg"
Unknown command "y"
Unknown command "startunuel"
Unknown command "startupmvevel"
Unknown command "startupmenvel"
Unknown command "startupmenuel"
Unknown command "startupmenu"
Network: IP ***, mode MP, dedicated Yes, ports 27015 SV / 27005 CL

(I replaced the IP with *s, that was deliberate)

Any help is appreciated.

EDIT:

I have looked into my server's IPTables configuration, and this is what my IPTables looks like:

Chain INPUT (policy ACCEPT)
target     prot opt source               destination
ACCEPT     tcp  --  anywhere             anywhere             tcp dpt:27015
ACCEPT     udp  --  anywhere             anywhere             udp dpt:27015

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination
ACCEPT     tcp  --  anywhere             anywhere             tcp dpt:http

And I have been told that this should make it work, in terms of port redirection. Even so, I have tried running the server using sudo, and it does not have any effect. Therefore, I think it isn't an issue with my server.