diff --git a/Command/EnableTor.hs b/Command/EnableTor.hs
index c581fa1d4b..d24ecb2dc7 100644
--- a/Command/EnableTor.hs
+++ b/Command/EnableTor.hs
@@ -8,27 +8,28 @@
 module Command.EnableTor where
 
 import Command
+import P2P.Address
 import Utility.Tor
+import Annex.UUID
 
 -- This runs as root, so avoid making any commits or initializing
--- git-annex, as that would create root-owned files.
+-- git-annex, or doing other things that create root-owned files.
 cmd :: Command
 cmd = noCommit $ dontCheck repoExists $
-	command "enable-tor" SectionSetup ""
-		"userid uuid" (withParams seek)
+	command "enable-tor" SectionSetup "enable tor hidden service"
+		"uid" (withParams seek)
 
 seek :: CmdParams -> CommandSeek
 seek = withWords start
 
-start :: CmdParams -> CommandStart
-start (suserid:uuid:[]) = case readish suserid of
-	Nothing -> error "Bad userid"
+start :: [String] -> CommandStart
+start ps = case readish =<< headMaybe ps of
+	Nothing -> giveup "Bad params"
 	Just userid -> do
-		(OnionAddress onionaddr, onionport) <- liftIO $
-			addHiddenService userid uuid
-		liftIO $ putStrLn $ 
-			"tor-annex::" ++
-			onionaddr ++ ":" ++ 
-			show onionport ++ " "
+		uuid <- getUUID
+		when (uuid == NoUUID) $
+			giveup "This can only be run in a git-annex repository."
+		(onionaddr, onionport) <- liftIO $
+			addHiddenService userid (fromUUID uuid)
+		storeP2PAddress $ TorAnnex onionaddr onionport
 		stop
-start _ = error "Bad params"
diff --git a/Creds.hs b/Creds.hs
index de3cd2a063..b5181aa1e3 100644
--- a/Creds.hs
+++ b/Creds.hs
@@ -15,6 +15,7 @@ module Creds (
 	getEnvCredPair,
 	writeCacheCreds,
 	readCacheCreds,
+	cacheCredsFile,
 	removeCreds,
 	includeCredsInfo,
 ) where
diff --git a/P2P/Address.hs b/P2P/Address.hs
new file mode 100644
index 0000000000..315219683f
--- /dev/null
+++ b/P2P/Address.hs
@@ -0,0 +1,79 @@
+{- P2P protocol addresses
+ -
+ - Copyright 2016 Joey Hess <id@joeyh.name>
+ -
+ - Licensed under the GNU GPL version 3 or higher.
+ -}
+
+module P2P.Address where
+
+import qualified Annex
+import Annex.Common
+import Git
+import Creds
+import Utility.AuthToken
+import Utility.Tor
+
+import qualified Data.Text as T
+
+-- | A P2P address, without an AuthToken.
+--
+-- This is enough information to connect to the peer,
+-- but not enough to authenticate with it.
+data P2PAddress = TorAnnex OnionAddress OnionPort
+	deriving (Eq, Show)
+
+-- | A P2P address, with an AuthToken
+data P2PAddressAuth = P2PAddressAuth P2PAddress AuthToken
+	deriving (Eq, Show)
+
+class FormatP2PAddress a where
+	formatP2PAddress :: a -> String
+	unformatP2PAddress :: String -> Maybe a
+
+instance FormatP2PAddress P2PAddress where
+	formatP2PAddress (TorAnnex (OnionAddress onionaddr) onionport) =
+		"tor-annex::" ++ onionaddr ++ ":" ++ show onionport
+	unformatP2PAddress s
+		| "tor-annex::" `isPrefixOf` s = do
+			let s' = dropWhile (== ':') $ dropWhile (/= ':') s
+			let (onionaddr, ps) = separate (== ':') s'
+			onionport <- readish ps
+			return (TorAnnex (OnionAddress onionaddr) onionport)
+		| otherwise = Nothing
+
+instance FormatP2PAddress P2PAddressAuth where
+	formatP2PAddress (P2PAddressAuth addr authtoken) =
+		formatP2PAddress addr ++ ":" ++ T.unpack (fromAuthToken authtoken)
+	unformatP2PAddress s = do
+		let (ra, rs) = separate (== ':') (reverse s)
+		addr <- unformatP2PAddress (reverse rs)
+		authtoken <- toAuthToken (T.pack $ reverse ra)
+		return (P2PAddressAuth addr authtoken)
+
+loadP2PAddresses :: Annex [P2PAddress]
+loadP2PAddresses = mapMaybe unformatP2PAddress . maybe [] lines
+	<$> readCacheCreds p2pAddressCredsFile
+
+storeP2PAddress :: P2PAddress -> Annex ()
+storeP2PAddress addr = do
+	addrs <- loadP2PAddresses
+	unless (addr `elem` addrs) $ do
+		let s = unlines $ map formatP2PAddress (addr:addrs)
+		let tmpnam = p2pAddressCredsFile ++ ".new"
+		writeCacheCreds s tmpnam
+		tmpf <- cacheCredsFile tmpnam
+		destf <- cacheCredsFile p2pAddressCredsFile
+		-- This may be run by root, so make the creds file
+		-- and directory have the same owner and group as
+		-- the git repository directory has.
+		st <- liftIO . getFileStatus =<< Annex.fromRepo repoLocation
+		let fixowner f = setOwnerAndGroup f (fileOwner st) (fileGroup st)
+		liftIO $ do
+			fixowner tmpf
+			fixowner (takeDirectory tmpf)
+			fixowner (takeDirectory (takeDirectory tmpf))
+			renameFile tmpf destf
+
+p2pAddressCredsFile :: FilePath
+p2pAddressCredsFile = "p2paddrs"
diff --git a/Utility/Tor.hs b/Utility/Tor.hs
index 3b9ddb6a62..e63bd82d4c 100644
--- a/Utility/Tor.hs
+++ b/Utility/Tor.hs
@@ -21,7 +21,7 @@ import qualified System.Random as R
 type OnionPort = Int
 
 newtype OnionAddress = OnionAddress String
-	deriving (Show)
+	deriving (Show, Eq)
 
 type OnionSocket = FilePath
 
@@ -57,7 +57,7 @@ addHiddenService uid ident = do
 	case filter (\(_, s) -> s == sockfile) portssocks of
 		((p, _s):_) -> waithiddenservice 1 p
 		_ -> do
-			highports <- R.getStdRandom highports
+			highports <- R.getStdRandom mkhighports
 			let newport = Prelude.head $
 				filter (`notElem` map fst portssocks) highports
 			writeFile torrc $ unlines $
@@ -74,7 +74,7 @@ addHiddenService uid ident = do
 				, ("sefvice", [Param "tor", Param "reload"])
 				]
 			unless reloaded $
-				error "failed to reload tor, perhaps the tor service is not running"
+				giveup "failed to reload tor, perhaps the tor service is not running"
 			waithiddenservice 120 newport
   where
 	parseportsock ("HiddenServicePort", l) = do
@@ -85,12 +85,12 @@ addHiddenService uid ident = do
 	sockfile = hiddenServiceSocketFile uid ident
 
 	-- An infinite random list of high ports.
-	highports g = 
+	mkhighports g = 
 		let (g1, g2) = R.split g
 		in (R.randomRs (1025, 65534) g1, g2)
 
 	waithiddenservice :: Int -> OnionPort -> IO (OnionAddress, OnionPort)
-	waithiddenservice 0 _ = error "tor failed to create hidden service, perhaps the tor service is not running"
+	waithiddenservice 0 _ = giveup "tor failed to create hidden service, perhaps the tor service is not running"
 	waithiddenservice n p = do
 		v <- tryIO $ readFile $ hiddenServiceHostnameFile uid ident
 		case v of
diff --git a/doc/git-annex-enable-tor.mdwn b/doc/git-annex-enable-tor.mdwn
index 9fb55db5f2..1c17380276 100644
--- a/doc/git-annex-enable-tor.mdwn
+++ b/doc/git-annex-enable-tor.mdwn
@@ -4,20 +4,18 @@ git-annex enable-tor - enable tor hidden service
 
 # SYNOPSIS
 
-git annex enable-tor userid uuid
+sudo git annex enable-tor $(id -u)
 
 # DESCRIPTION
 
-This plumbing-level command enables a tor hidden service for git-annex,
-using the specified repository uuid and userid. 
+This command enables a tor hidden service for git-annex.
 
-This command has to be run by root, since it modifies `/etc/tor/torrc`.
+It has to be run by root, since it modifies `/etc/tor/torrc`.
+Pass it your user id number, as output by `id -u`
 
 After this command is run, `git annex remotedaemon` can be run to serve the
-tor hidden service.
-
-Use the `git-annex p2p --gen-address` command to give other users access
-to your repository via the tor hidden service.
+tor hidden service, and then `git-annex p2p --gen-address` can be run to
+give other users access to your repository via the tor hidden service.
 
 # SEE ALSO
 
diff --git a/git-annex.cabal b/git-annex.cabal
index bd8c36063f..5a446ac7a8 100644
--- a/git-annex.cabal
+++ b/git-annex.cabal
@@ -904,6 +904,7 @@ Executable git-annex
     Messages.Internal
     Messages.JSON
     Messages.Progress
+    P2P.Address
     P2P.Auth
     P2P.IO
     P2P.Protocol