diff --git a/provision-contest/ansible/roles/clusterssh/files/tmux-cssh b/provision-contest/ansible/roles/clusterssh/files/tmux-cssh
new file mode 100644
index 00000000..41862edf
--- /dev/null
+++ b/provision-contest/ansible/roles/clusterssh/files/tmux-cssh
@@ -0,0 +1,130 @@
+#!/bin/sh
+
+hosts=""
+ssh_options=""
+tmux_name="cssh"
+tmux_attach_current_session="false"
+
+usage() {
+  echo "Usage: $0 [options] host [host ...]" >&2
+  echo "" >&2
+  echo "Spawns multiple synchronized SSH sessions inside a tmux session." >&2
+  echo "" >&2
+  echo "Options:" >&2
+  echo "  -h                  Show help" >&2
+  echo "  -c                  Use the current tmux session and just spawn a new window instead" >&2
+  echo "  -n <name>           Name of the tmux session or window (default: cssh)" >&2
+  echo "  -o <ssh args>       Additional SSH arguments" >&2
+}
+
+while [ $# -ne 0 ]; do
+  case $1 in
+    -n)
+      shift
+      if [ $# -eq 0 ]; then
+        usage
+        exit 2
+      fi
+      tmux_name="$1"
+      shift
+      ;;
+    -c)
+      tmux_attach_current_session="true"
+      shift
+      ;;
+    -o)
+      shift
+      if [ $# -eq 0 ]; then
+        usage
+        exit 2
+      fi
+      ssh_options="$1"
+      shift
+      ;;
+    -h)
+      usage
+      exit 0
+      ;;
+    -*)
+      usage
+      exit 2
+      ;;
+    *)
+      hosts="${hosts}${hosts:+ }$1"
+      shift
+      ;;
+  esac
+done
+
+if [ -z "${hosts}" ]; then
+  usage
+  exit 2
+fi
+
+# Find a name for a new session
+n=0
+while tmux has-session -t "${tmux_name}-${n}" 2>/dev/null; do n=$((n + 1)); done
+tmux_session="${tmux_name}-${n}"
+
+if [ "${tmux_attach_current_session}" = "true" ]; then
+  tmux_session="$(tmux display-message -p '#S')"
+  # Find a name for a new window
+  n=0
+  while tmux list-windows -F "#W" | grep -q "${tmux_name}-${n}" 2>/dev/null; do n=$((n + 1)); done
+  tmux_window="${tmux_name}-${n}"
+  tmux_window_options="-n ${tmux_window}"
+fi
+
+# If host doesn't look like a DNS name, it may be a CSSH cluster
+if ! echo "${hosts}" | grep -q '[. ]'; then
+  for cfg in "${HOME}/.clusterssh/clusters" /etc/clusters; do
+    if [ -r "${cfg}" ]; then
+      h="$(sed -n "s/^${hosts} //p" <"${cfg}")"
+      if [ -n "${h}" ]; then
+        hosts="${h}"
+        break
+      fi
+    fi
+    # If there was no corresponding cluster name,
+    # just assume we have an unqualified domain name
+  done
+fi
+
+# Open a new session and split into new panes for each SSH session
+for host in ${hosts}; do
+  if ! tmux has-session -t "${tmux_session}" 2>/dev/null; then
+    tmux new-session -s "${tmux_session}" -d "ssh ${ssh_options} ${host}"
+  elif [ "${tmux_attach_current_session}" = "true" ]; then
+    if ! tmux list-windows -F "#W" | grep -q "${tmux_window}" >/dev/null; then
+      # shellcheck disable=SC2086
+      tmux new-window ${tmux_window_options} "ssh ${ssh_options} ${host}"
+    else
+      tmux split-window -t "${tmux_window}" -d "ssh ${ssh_options} ${host}"
+      # We have to reset the layout after each new pane otherwise the panes
+      # quickly become too small to spawn any more
+      tmux select-layout -t "${tmux_session}" tiled
+    fi
+  else
+    tmux split-window -t "${tmux_session}" -d "ssh ${ssh_options} ${host}"
+    # We have to reset the layout after each new pane otherwise the panes
+    # quickly become too small to spawn any more
+    tmux select-layout -t "${tmux_session}" tiled
+  fi
+done
+
+# Synchronize panes by default
+if [ "${tmux_attach_current_session}" = "true" ]; then
+  tmux set-window-option -t "${tmux_window}" synchronize-panes on
+else
+  tmux set-window-option -t "${tmux_session}" synchronize-panes on
+fi
+
+if [ -n "${TMUX}" ]; then
+  # We are in a tmux, just switch to the new session
+  tmux switch-client -t "${tmux_session}"
+else
+  # We are NOT in a tmux, attach to the new session
+  tmux attach-session -t "${tmux_session}"
+fi
+
+exit 0
diff --git a/provision-contest/ansible/roles/clusterssh/tasks/main.yml b/provision-contest/ansible/roles/clusterssh/tasks/main.yml
index 585432da..1ae21350 100644
--- a/provision-contest/ansible/roles/clusterssh/tasks/main.yml
+++ b/provision-contest/ansible/roles/clusterssh/tasks/main.yml
@@ -22,3 +22,46 @@
     src: clusters.j2
     dest: /home/domjudge/.clusterssh/clusters
     mode: 0644
+
+- name: Install tmux-cssh
+  when: not WF_RESTRICTED_NETWORK
+  get_url:
+    url: https://raw.githubusercontent.com/peikk0/tmux-cssh/master/tmux-cssh
+    dest: /usr/local/bin/tmux-cssh
+    mode: 0755
+    owner: root
+    group: root
+
+- name: Install tmux-cssh
+  when: WF_RESTRICTED_NETWORK
+  copy:
+    src: tmux-cssh
+    dest: /usr/local/bin/tmux-cssh
+    mode: 0755
+    owner: root
+    group: root
+
+- name: Set tmux-cssh shorthands
+  template:
+    owner: root
+    group: root
+    mode: 0755
+    src: tmux-cluster.sh.j2
+    dest: /usr/local/bin/{{ item.short }}
+  loop:
+    - short: ssh-js
+      group: wfinal-judgehost
+    - short: ssh-jsanalyst
+      group: analyst-judgehost
+    - short: ssh-jsall
+      group: judgehost
+    - short: ssh-dom
+      group: wfinal-domserver
+    - short: ssh-domanalyst
+      group: analyst-domserver
+    - short: ssh-domall
+      group: domserver
+    - short: ssh-all
+      group: onprem
+    - short: ssh-admin
+      group: admin
diff --git a/provision-contest/ansible/roles/clusterssh/templates/tmux-cluster.sh.j2 b/provision-contest/ansible/roles/clusterssh/templates/tmux-cluster.sh.j2
new file mode 100644
index 00000000..a995a600
--- /dev/null
+++ b/provision-contest/ansible/roles/clusterssh/templates/tmux-cluster.sh.j2
@@ -0,0 +1,3 @@
+#!/usr/bin/sh
+
+tmux-cssh {% for host in groups[item.group] %}{{ host }} {% endfor %}