*Observed Behavior:
Querying the database via LINQ to entities fails with an InvalidOperationException: No user name was specified.

*Expected Behavior*
No exception

*Cause*
FbProviderServices.GetDbProviderManifestToken creates a new connection through FbServerProperties if the given DbConnection is not already open. FbServerProperties, or more specifically its base classe, FbService does not support Trusted Authentication. FbService.Open specifically checks for the existence of a user name and password and throws an exception.

FbService.cs:
{code}
protected void Open()
{
if (State != FbServiceState.Closed)
throw new InvalidOperationException("Service already Open.");
if (string.IsNullOrEmpty(_csManager.UserID))
throw new InvalidOperationException("No user name was specified.");
if (string.IsNullOrEmpty(_csManager.Password))
throw new InvalidOperationException("No user password was specified.");
{code}

By contrast, FbConnectionInternal first checks for the existence of a user name and password, and branches into trusted authentication. Similar code seems to be missing in FbService.cs.
FbConnectionInternal.cs:
{code}
    public void Connect()
    {
      if (Charset.GetCharset(this.options.Charset) == null)
        throw new FbException("Invalid character set specified");
      try
      {
        this.db = ClientFactory.CreateDatabase(this.options);
        this.db.Charset = Charset.GetCharset(this.options.Charset);
        this.db.Dialect = (short) this.options.Dialect;
        this.db.PacketSize = this.options.PacketSize;
        DatabaseParameterBuffer dpb = this.BuildDpb(this.db, this.options);
        if (this.options.FallIntoTrustedAuth)
          this.db.AttachWithTrustedAuth(dpb, this.options.DataSource, this.options.Port, this.options.Database);
        else
          this.db.Attach(dpb, this.options.DataSource, this.options.Port, this.options.Database);
      }
{code}

*Workaround*
Opening the connection manually before passing it into DbContext is a workaround.

*Stack Trace*
> FirebirdSql.Data.FirebirdClient.dll!FirebirdSql.Data.Services.FbService.Open() Line 108 C#
  FirebirdSql.Data.FirebirdClient.dll!FirebirdSql.Data.Services.FbService.QueryService(byte[] items) Line 346 C#
  FirebirdSql.Data.FirebirdClient.dll!FirebirdSql.Data.Services.FbService.ProcessQuery(byte[] items, System.Action<bool, object> queryResponseAction) Line 235 C#
  FirebirdSql.Data.FirebirdClient.dll!FirebirdSql.Data.Services.FbService.Query(byte[] items) Line 199 C#
  FirebirdSql.Data.FirebirdClient.dll!FirebirdSql.Data.Services.FbServerProperties.GetInfo(int item) Line 87 C#
  FirebirdSql.Data.FirebirdClient.dll!FirebirdSql.Data.Services.FbServerProperties.GetString(int item) Line 77 C#
  EntityFramework.Firebird.dll!FirebirdSql.Data.EntityFramework6.FbProviderServices.GetDbProviderManifestToken(System.Data.Common.DbConnection connection) Line 154 C#
  EntityFramework.dll!System.Data.Entity.Core.Common.DbProviderServices.GetProviderManifestToken(System.Data.Common.DbConnection connection) Unknown
  EntityFramework.dll!System.Data.Entity.Utilities.DbProviderServicesExtensions.GetProviderManifestTokenChecked(System.Data.Entity.Core.Common.DbProviderServices providerServices, System.Data.Common.DbConnection connection) Unknown
  mscorlib.dll!System.Collections.Concurrent.ConcurrentDictionary<System.Tuple<System.Type, string, string>, string>.GetOrAdd(System.Tuple<System.Type, string, string> key, System.Func<System.Tuple<System.Type, string, string>, string> valueFactory) Unknown
  EntityFramework.dll!System.Data.Entity.Utilities.DbConnectionExtensions.GetProviderInfo(System.Data.Common.DbConnection connection, out System.Data.Entity.Core.Common.DbProviderManifest providerManifest) Unknown
  EntityFramework.dll!System.Data.Entity.DbModelBuilder.Build(System.Data.Common.DbConnection providerConnection) Unknown
  EntityFramework.dll!System.Data.Entity.Internal.LazyInternalContext.CreateModel(System.Data.Entity.Internal.LazyInternalContext internalContext) Unknown
  EntityFramework.dll!System.Data.Entity.Internal.RetryLazy<System.Data.Entity.Internal.LazyInternalContext, System.Data.Entity.Infrastructure.DbCompiledModel>.GetValue(System.Data.Entity.Internal.LazyInternalContext input) Unknown
  EntityFramework.dll!System.Data.Entity.Internal.LazyInternalContext.InitializeContext() Unknown
  EntityFramework.dll!System.Data.Entity.Internal.InternalContext.GetEntitySetAndBaseTypeForType(System.Type entityType) Unknown
  EntityFramework.dll!System.Data.Entity.Internal.Linq.InternalSet<Settings.DataAccess.Entities.SettingEntity>.Initialize() Unknown
  EntityFramework.dll!System.Data.Entity.Internal.Linq.InternalSet<Settings.DataAccess.Entities.SettingEntity>.InternalContext.get() Unknown
  EntityFramework.dll!System.Data.Entity.Infrastructure.DbQuery<Settings.DataAccess.Entities.SettingEntity>.System.Linq.IQueryable.Provider.get() Unknown
  System.Core.dll!System.Linq.Queryable.Where<Settings.DataAccess.Entities.SettingEntity>(System.Linq.IQueryable<Settings.DataAccess.Entities.SettingEntity> source, System.Linq.Expressions.Expression<System.Func<Settings.DataAccess.Entities.SettingEntity, bool>> predicate) Unknown

*Connection String*
character set=UTF8;initial catalog=path\to\data.fdb;ServerType=0