diff --git a/src/bin/options.ts b/src/bin/options.ts
index 3216f6fa31..1ba987eebf 100644
--- a/src/bin/options.ts
+++ b/src/bin/options.ts
@@ -1,3 +1,9 @@
+import type { NodeAddress, NodeId, NodeMapping } from '../nodes/types';
+import type { Host, Hostname, Port } from '../network/types';
+import * as nodesUtils from '../nodes/utils';
+import * as networkUtils from '../network/utils';
+import * as errors from '../errors';
+
 import commander from 'commander';
 import config from '../config';
 
@@ -9,6 +15,76 @@ function parseNumber(v: string): number {
   return num;
 }
 
+/**
+ * Seed nodes expected to be of form 'nodeId1@host:port;nodeId2@host:port;...'
+ * By default, any specified seed nodes (in CLI option, or environment variable)
+ * will overwrite the default nodes in src/config.ts.
+ * Special flag '<seed-nodes>' in the content indicates that the default seed
+ * nodes should be added to the starting seed nodes instead of being overwritten.
+ */
+function parseSeedNodes(rawSeedNodes: string): NodeMapping {
+  const seedNodeMappings: NodeMapping = {};
+  // If specifically set no seed nodes, then ensure we start with none
+  if (rawSeedNodes == '') return seedNodeMappings;
+  const semicolonSeedNodes = rawSeedNodes.split(';');
+  for (const rawSeedNode of semicolonSeedNodes) {
+    // Empty string will occur if there's an extraneous ';' (e.g. at end of env)
+    if (rawSeedNode == '') continue;
+    // Append the default seed nodes if we encounter the special flag
+    if (rawSeedNode == '<seed-nodes>') {
+      const defaultSeedNodes = getDefaultSeedNodes();
+      for (const id in defaultSeedNodes) {
+        seedNodeMappings[id] = defaultSeedNodes[id];
+      }
+    }
+    const idHostPort = rawSeedNode.split(/[@:]/);
+    if (idHostPort.length != 3) {
+      throw new commander.InvalidOptionArgumentError(`${rawSeedNode} is not of format 'nodeId@host:port'`)
+    }
+    if (!nodesUtils.isNodeId(idHostPort[0])) {
+      throw new commander.InvalidOptionArgumentError(`${idHostPort[0]} is not a valid node ID`);
+    }
+    if (!networkUtils.isValidHostname(idHostPort[1])) {
+      throw new commander.InvalidOptionArgumentError(`${idHostPort[1]} is not a valid hostname`);
+    }
+    const port = parseNumber(idHostPort[2]);
+    const seedNodeId = idHostPort[0] as NodeId;
+    const seedNodeAddress: NodeAddress = {
+      host: idHostPort[1] as Host | Hostname,
+      port: port as Port,
+    };
+    seedNodeMappings[seedNodeId] = seedNodeAddress;
+  }
+  return seedNodeMappings;
+}
+
+/**
+ * Acquires the default seed nodes from src/config.ts.
+ */
+function getDefaultSeedNodes(): NodeMapping {
+  const seedNodes: NodeMapping = {};
+  let source;
+  switch (config.environment) {
+    case 'testnet':
+      source = config.seedNodesTest;
+      break;
+    case 'mainnet':
+      source = config.seedNodesMain;
+      break;
+    default:
+      throw new errors.ErrorInvalidConfigEnvironment();
+  }
+  for (const id in source) {
+    const seedNodeId = id as NodeId;
+    const seedNodeAddress: NodeAddress = {
+      host: source[seedNodeId].host as Host | Hostname,
+      port: source[seedNodeId].port as Port,
+    }
+    seedNodes[seedNodeId] = seedNodeAddress;
+  }
+  return seedNodes;
+}
+
 const clientHost = new commander.Option(
   '-ch, --client-host <address>',
   'Client Host Address',
@@ -45,4 +121,12 @@ const ingressPort = new commander.Option(
   .env('PK_INGRESS_PORT')
   .default(config.defaults.clientPort);
 
-export { clientHost, clientPort, ingressHost, ingressPort, hostParser };
+const seedNodes = new commander.Option(
+  '-sn, --seed-nodes [nodeId1@host:port;nodeId2@host:port;...]',
+  'Seed node address mappings',
+)
+  .argParser(parseSeedNodes)
+  .env('PK_SEED_NODES')
+  .default(getDefaultSeedNodes());
+
+export { clientHost, clientPort, ingressHost, ingressPort, seedNodes, hostParser };
diff --git a/src/config.ts b/src/config.ts
index 2298b620b0..ce54f82a65 100644
--- a/src/config.ts
+++ b/src/config.ts
@@ -15,6 +15,13 @@ const config = {
     clientHost: 'localhost',
     clientPort: 0,
   },
+  environment: 'testnet',
+  seedNodesTest: {
+    'SEEDNODE1' : { host: 'testnet.polykey.io', port: 1314 },
+  },
+  seedNodesMain: {
+    'SEEDNODE1' : { host: 'testnet.polykey.io', port: 1314 },
+  },
 };
 
 export default config;
diff --git a/src/errors.ts b/src/errors.ts
index d795bd1bb2..2e4ba01b19 100644
--- a/src/errors.ts
+++ b/src/errors.ts
@@ -36,6 +36,8 @@ class ErrorStateVersionMismatch extends ErrorPolykey {}
 
 class ErrorInvalidId extends ErrorPolykey {}
 
+class ErrorInvalidConfigEnvironment extends ErrorPolykey {}
+
 export {
   ErrorPolykey,
   ErrorPolykeyAgentNotRunning,
@@ -45,6 +47,7 @@ export {
   ErrorUndefinedBehaviour,
   ErrorStateVersionMismatch,
   ErrorInvalidId,
+  ErrorInvalidConfigEnvironment,
 };
 
 /**
diff --git a/src/network/utils.ts b/src/network/utils.ts
index 744dc3bad8..bfc197bcf5 100644
--- a/src/network/utils.ts
+++ b/src/network/utils.ts
@@ -63,6 +63,13 @@ function parseAddress(address: string): [Host, Port] {
   return isIPv4 || isIPv6;
 }
 
+/**
+ * Validates that a provided hostname is valid, as per RFC 1123.
+ */
+function isValidHostname(hostname: string): boolean {
+  return (hostname.match(/^(([a-zA-Z0-9]|[a-zA-Z0-9][a-zA-Z0-9\-]*[a-zA-Z0-9])\.)*([A-Za-z0-9]|[A-Za-z0-9][A-Za-z0-9\-]*[A-Za-z0-9])$/)) ? true : false;
+}
+
 /**
  * Resolves a provided hostname to its respective IP address (type Host).
  */
@@ -348,6 +355,7 @@ export {
   buildAddress,
   parseAddress,
   isValidHost,
+  isValidHostname,
   resolveHost,
   resolvesZeroIP,
   serializeNetworkMessage,
diff --git a/src/nodes/NodeManager.ts b/src/nodes/NodeManager.ts
index 5ac6e4d0a2..8ae22b01c7 100644
--- a/src/nodes/NodeManager.ts
+++ b/src/nodes/NodeManager.ts
@@ -6,6 +6,7 @@ import type { ClaimIdString } from '../claims/types';
 import type {
   NodeId,
   NodeAddress,
+  NodeMapping,
   NodeData,
   NodeBucket,
   NodeConnectionMap,
@@ -52,7 +53,7 @@ class NodeManager {
   // Active connections to other nodes
   protected connections: NodeConnectionMap = new Map();
   // Node ID -> node address mappings for the seed nodes
-  protected seedNodes: NodeBucket = {};
+  protected seedNodes: NodeMapping = {};
 
   static async createNodeManager({
     db,
@@ -128,7 +129,7 @@ class NodeManager {
     seedNodes = {},
     fresh = false,
   }: {
-    seedNodes?: NodeBucket;
+    seedNodes?: NodeMapping;
     fresh?: boolean;
   } = {}) {
     this.logger.info('Starting Node Manager');
@@ -139,7 +140,7 @@ class NodeManager {
     // Add the seed nodes to the NodeGraph and establish connections to them
     for (const id in seedNodes) {
       const seedNodeId = id as NodeId;
-      await this.nodeGraph.setNode(seedNodeId, seedNodes[seedNodeId].address);
+      await this.nodeGraph.setNode(seedNodeId, seedNodes[seedNodeId]);
       await this.getConnectionToNode(seedNodeId);
     }
     this.logger.info('Started Node Manager');
diff --git a/src/nodes/types.ts b/src/nodes/types.ts
index e5815aa647..0e55a7af1c 100644
--- a/src/nodes/types.ts
+++ b/src/nodes/types.ts
@@ -13,6 +13,10 @@ type NodeAddress = {
   port: Port;
 };
 
+type NodeMapping = {
+  [key: string]: NodeAddress;
+};
+
 type NodeData = {
   id: NodeId;
   address: NodeAddress;
@@ -83,6 +87,7 @@ type NodeGraphOp =
 export type {
   NodeId,
   NodeAddress,
+  NodeMapping,
   NodeData,
   NodeClaim,
   NodeInfo,
diff --git a/tests/nodes/NodeManager.test.ts b/tests/nodes/NodeManager.test.ts
index 7a08e2dc04..bb8d7f7003 100644
--- a/tests/nodes/NodeManager.test.ts
+++ b/tests/nodes/NodeManager.test.ts
@@ -147,7 +147,7 @@ describe('NodeManager', () => {
       await target.start({});
       targetNodeId = target.keys.getNodeId();
       targetNodeAddress = {
-        ip: target.revProxy.getIngressHost(),
+        host: target.revProxy.getIngressHost(),
         port: target.revProxy.getIngressPort(),
       };
       await nodeManager.setNode(targetNodeId, targetNodeAddress);
@@ -213,7 +213,7 @@ describe('NodeManager', () => {
       async () => {
         // Add the dummy node
         await nodeManager.setNode(dummyNode, {
-          ip: '125.0.0.1' as Host,
+          host: '125.0.0.1' as Host,
           port: 55555 as Port,
         });
         // @ts-ignore accessing protected NodeConnectionMap
@@ -249,7 +249,7 @@ describe('NodeManager', () => {
       });
       const serverNodeId = server.nodes.getNodeId();
       let serverNodeAddress: NodeAddress = {
-        ip: server.revProxy.getIngressHost(),
+        host: server.revProxy.getIngressHost(),
         port: server.revProxy.getIngressPort(),
       };
       await nodeManager.setNode(serverNodeId, serverNodeAddress);
@@ -264,7 +264,7 @@ describe('NodeManager', () => {
       await server.start({});
       // Update the node address (only changes because we start and stop)
       serverNodeAddress = {
-        ip: server.revProxy.getIngressHost(),
+        host: server.revProxy.getIngressHost(),
         port: server.revProxy.getIngressPort(),
       };
       await nodeManager.setNode(serverNodeId, serverNodeAddress);
@@ -291,7 +291,7 @@ describe('NodeManager', () => {
     // Case 1: node already exists in the local node graph (no contact required)
     const nodeId = nodeId1;
     const nodeAddress: NodeAddress = {
-      ip: '127.0.0.1' as Host,
+      host: '127.0.0.1' as Host,
       port: 11111 as Port,
     };
     await nodeManager.setNode(nodeId, nodeAddress);
@@ -306,12 +306,12 @@ describe('NodeManager', () => {
       // Case 2: node can be found on the remote node
       const nodeId = nodeId1;
       const nodeAddress: NodeAddress = {
-        ip: '127.0.0.1' as Host,
+        host: '127.0.0.1' as Host,
         port: 11111 as Port,
       };
       const server = await testUtils.setupRemoteKeynode({ logger: logger });
       await nodeManager.setNode(server.nodes.getNodeId(), {
-        ip: server.revProxy.getIngressHost(),
+        host: server.revProxy.getIngressHost(),
         port: server.revProxy.getIngressPort(),
       } as NodeAddress);
       await server.nodes.setNode(nodeId, nodeAddress);
@@ -329,14 +329,14 @@ describe('NodeManager', () => {
       const nodeId = nodeId1;
       const server = await testUtils.setupRemoteKeynode({ logger: logger });
       await nodeManager.setNode(server.nodes.getNodeId(), {
-        ip: server.revProxy.getIngressHost(),
+        host: server.revProxy.getIngressHost(),
         port: server.revProxy.getIngressPort(),
       } as NodeAddress);
       // Add a dummy node to the server node graph database
       // Server will not be able to connect to this node (the only node in its
       // database), and will therefore not be able to locate the node.
       await server.nodes.setNode(dummyNode, {
-        ip: '127.0.0.2' as Host,
+        host: '127.0.0.2' as Host,
         port: 22222 as Port,
       } as NodeAddress);
       // So unfindableNode cannot be found
@@ -351,7 +351,7 @@ describe('NodeManager', () => {
   test('knows node (true and false case)', async () => {
     // Known node
     const nodeAddress1: NodeAddress = {
-      ip: '127.0.0.1' as Host,
+      host: '127.0.0.1' as Host,
       port: 11111 as Port,
     };
     await nodeManager.setNode(nodeId1, nodeAddress1);
@@ -386,7 +386,7 @@ describe('NodeManager', () => {
       });
       xNodeId = x.nodes.getNodeId();
       xNodeAddress = {
-        ip: x.revProxy.getIngressHost(),
+        host: x.revProxy.getIngressHost(),
         port: x.revProxy.getIngressPort(),
       };
       xPublicKey = x.keys.getRootKeyPairPem().publicKey;
@@ -396,7 +396,7 @@ describe('NodeManager', () => {
       });
       yNodeId = y.nodes.getNodeId();
       yNodeAddress = {
-        ip: y.revProxy.getIngressHost(),
+        host: y.revProxy.getIngressHost(),
         port: y.revProxy.getIngressPort(),
       };
       yPublicKey = y.keys.getRootKeyPairPem().publicKey;