diff --git a/.gitea/workflows/build.yaml b/.gitea/workflows/build.yaml
index 7e082e5..6c71d32 100644
--- a/.gitea/workflows/build.yaml
+++ b/.gitea/workflows/build.yaml
@@ -26,8 +26,12 @@ jobs:
           chmod 600 ~/.ssh/id_ed25519
           echo ">>> chmod public key"
           chmod 600 ~/.ssh/id_ed25519.pub
+          echo ">>> dns resolve"
+          nslookup focs.gc.sjtu.edu.cn || host focs.gc.sjtu.edu.cn || echo "DNS failed"
+          echo ">>> tcp test"
+          timeout 5 bash -c "echo >/dev/tcp/focs.gc.sjtu.edu.cn/2222" 2>&1 || echo "TCP failed"
           echo ">>> ssh-keyscan"
-          ssh-keyscan -p 2222 focs.gc.sjtu.edu.cn >> ~/.ssh/known_hosts
+          timeout 10 ssh-keyscan -p 2222 focs.gc.sjtu.edu.cn >> ~/.ssh/known_hosts || echo "ssh-keyscan failed"
           echo ">>> ssh test"
           ssh -T git@focs.gc.sjtu.edu.cn -p 2222
         # - name: Lint
diff --git a/.gitea/workflows/submodule.yaml b/.gitea/workflows/submodule.yaml
index e4ed025..dba8c2b 100644
--- a/.gitea/workflows/submodule.yaml
+++ b/.gitea/workflows/submodule.yaml
@@ -23,8 +23,12 @@ jobs:
           chmod 600 ~/.ssh/id_ed25519
           echo ">>> chmod public key"
           chmod 600 ~/.ssh/id_ed25519.pub
+          echo ">>> dns resolve"
+          nslookup focs.gc.sjtu.edu.cn || host focs.gc.sjtu.edu.cn || echo "DNS failed"
+          echo ">>> tcp test"
+          timeout 5 bash -c "echo >/dev/tcp/focs.gc.sjtu.edu.cn/2222" 2>&1 || echo "TCP failed"
           echo ">>> ssh-keyscan"
-          ssh-keyscan -p 2222 focs.gc.sjtu.edu.cn >> ~/.ssh/known_hosts
+          timeout 10 ssh-keyscan -p 2222 focs.gc.sjtu.edu.cn >> ~/.ssh/known_hosts || echo "ssh-keyscan failed"
           echo ">>> ssh test"
           ssh -T git@focs.gc.sjtu.edu.cn -p 2222
       - name: Set up Git