Having been bitten by this for the n-th time (with n being subjectively a large integer), I’m noting this down for the following generations to benefit; and hopefully to save myself some fiddling next time it happens. Without further ado:
How to connect with SVN to a remote repository that is running on a non-standard SSH port
Normally you’d expect that entering something like “svn+ssh://myserver:port/path” as an SVN repository location in Eclipse should be enough. Unfortunately this won’t take us anywhere – either it won’t be able to connect to the server or the supplied credentials will fail.
The reason is that the default subversive SVN connector SVNKit doesn’t pick up the necessary settings and JavaHL reads SSH configuration which needs to be updated.
The solution – short
You’ll have to use the JavaHL connector, setup an ssh alias including the non-standart port and also use a keyfile for login; user/pwd won’t do it.
The solution – long
1. Switch subversive to JavaHL: Window -> Preferences ->SVN Connector -> Native JavaHL.
If the option is missing, you are either not using the subversive plugin (so get it maybe?) or you have not installed the JavaHL plugin (you also need to do that).
If JavaHL is available but disabled with an error about missing libraries, then install them in linux:
apt-get install libsvn-java
For more see  Installing JavaHL. In my installation Eclipse would still not pick up JavaHL, I needed an alternative installation:
apt-add-repository ppa:dominik-stadler/subversion-1.7 apt-get update apt-get dist-upgrade
2. Set up an alias in ~./ssh/config
Host example_alias HostName your.example.ssh.server Port 12345 User ssh_user
performing obvious substitutions
3. Create a local keyfile and upload it to the ssh server to enable login without password. For details see  Login to ssh without a password
Note that you will probably run into problems with ssh-copy-id with the port notation . Use:
ssh-copy-id "user@host -p port"
 Installing JavaHL
 Login to ssh without a password
 Use ssh-copy-id on a different port