diff --git a/src/server/auth-by-db.js b/src/server/auth-by-db.js
index dfcb958..0e77829 100644
--- a/src/server/auth-by-db.js
+++ b/src/server/auth-by-db.js
@@ -1,7 +1,8 @@
 import { createHmac } from "crypto";
 import { normalizeRow } from "./util";
 
-export async function getAuthToken({ username, password }, db) {
+
+export async function getAuthToken({ username, password, ipAddress }, db) {
   // For legacy reasons (and I guess decent security reasons too!), auth info
   // is stored in a users table in a separate database. First, look up the user
   // in that database, and get their encrypted auth info.
@@ -19,18 +20,12 @@ export async function getAuthToken({ username, password }, db) {
     return null;
   }
 
-  // Then, use the HMAC-SHA256 algorithm to validate the password the user is
-  // trying to log in with. The random salt for this user, saved in the
-  // database, is the HMAC "key". (That way, if our database leaks, each user's
-  // password would need to be cracked individually, instead of being
-  // susceptible to attacks where you match our database against a database of
-  // SHA256 hashes for common passwords.)
+  // Then, use the password encrpytion function to validate the password the
+  // user is trying to log in with.
   const { id, encryptedPassword, passwordSalt } = normalizeRow(
     rowsFromOpenneoId[0]
   );
-  const passwordHmac = createHmac("sha256", passwordSalt);
-  passwordHmac.update(password);
-  const encryptedProvidedPassword = passwordHmac.digest("hex");
+  const encryptedProvidedPassword = encryptPassword(password, passwordSalt);
 
   if (encryptedProvidedPassword !== encryptedPassword) {
     console.debug(
@@ -58,24 +53,53 @@ export async function getAuthToken({ username, password }, db) {
   }
   const { id: impressId } = normalizeRow(rowsFromOpenneoImpress[0]);
 
-  // Finally, create the auth token object. This contains a `userId` field, a
-  // `createdAt` field, and a signature of the object with every field but the
-  // `signature` field. The signature also uses HMAC-SHA256 (which doesn't at
-  // all need to be in sync with the password hashing, but it's a good
-  // algorithm so we chose it again), and the key this time is a secret global
-  // value called `DTI_AUTH_TOKEN_SECRET`. This proves that the auth token was
-  // generated by the app, because only the app knows the secret.
+  // One more thing: Update the user record to keep track of this login.
+  await db.query(
+    `
+    UPDATE openneo_id.users
+      SET last_sign_in_at = current_sign_in_at,
+        current_sign_in_at = CURRENT_TIMESTAMP(),
+        last_sign_in_ip = current_sign_in_ip,
+        current_sign_in_ip = ?,
+        sign_in_count = sign_in_count + 1,
+        updated_at = CURRENT_TIMESTAMP()
+      WHERE id = ? LIMIT 1;
+  `,
+    [ipAddress, id]
+  );
+
+  // Finally, create and return the auth token itself. The caller will handle
+  // setting it to a cookie etc.
+  const authToken = createAuthToken(impressId);
+  console.debug(`[getAuthToken] Succeeded: ${JSON.stringify(authToken)}`);
+  return authToken;
+}
+
+function createAuthToken(impressId) {
+  // This contains a `userId` field, a `createdAt` field, and a signature of
+  // the object with every field but the `signature` field. The signature also
+  // uses HMAC-SHA256 (which doesn't at all need to be in sync with the
+  // password hashing, but it's a good algorithm so we chose it again), and the
+  // key this time is a secret global value called `DTI_AUTH_TOKEN_SECRET`.
+  // This proves that the auth token was generated by the app, because only the
+  // app knows the secret.
   const unsignedAuthToken = {
     userId: impressId,
     createdAt: new Date().toISOString(),
   };
   const signature = computeSignatureForAuthToken(unsignedAuthToken);
-  const authToken = { ...unsignedAuthToken, signature };
+  return { ...unsignedAuthToken, signature };
+}
 
-  // Login success! Return the auth token. The caller will handle setting it to
-  // a cookie etc.
-  console.debug(`[getAuthToken] Succeeded: ${JSON.stringify(authToken)}`);
-  return authToken;
+function encryptPassword(password, passwordSalt) {
+  // Use HMAC-SHA256 to encrypt the password. The random salt for this user,
+  // saved in the database, is the HMAC "key". (That way, if our database
+  // leaks, each user's password would need to be cracked individually, instead
+  // of being susceptible to attacks where you match our database against a
+  // database of SHA256 hashes for common passwords.)
+  const passwordHmac = createHmac("sha256", passwordSalt);
+  passwordHmac.update(password);
+  return passwordHmac.digest("hex");
 }
 
 export async function getUserIdFromToken(authToken) {
diff --git a/src/server/index.js b/src/server/index.js
index b5619d7..7b902e5 100644
--- a/src/server/index.js
+++ b/src/server/index.js
@@ -80,6 +80,12 @@ const config = {
       currentUserId = null;
     }
 
+    // In production, the server is behind a few proxy layers (both nginx and
+    // the CDN), so this IP header will be managed by them and can be trusted.
+    // (Can be null if something is set up a bit different, e.g. in local
+    // development.)
+    const ipAddress = req?.headers?.["x-forwarded-for"] || null;
+
     return {
       db,
       currentUserId,
@@ -100,6 +106,7 @@ const config = {
           res.setHeader("Set-Cookie", `DTIAuthToken=; Max-Age=-1`);
         }
       },
+      ipAddress,
       ...buildLoaders(db),
     };
   },
diff --git a/src/server/types/User.js b/src/server/types/User.js
index 3b67bcc..12bc280 100644
--- a/src/server/types/User.js
+++ b/src/server/types/User.js
@@ -366,8 +366,15 @@ const resolvers = {
   },
 
   Mutation: {
-    login: async (_, { username, password }, { setAuthToken, db }) => {
-      const authToken = await getAuthToken({ username, password }, db);
+    login: async (
+      _,
+      { username, password },
+      { setAuthToken, db, ipAddress }
+    ) => {
+      const authToken = await getAuthToken(
+        { username, password, ipAddress },
+        db
+      );
       if (authToken == null) {
         return null;
       }