diff --git a/docker-compose.yml b/docker-compose.yml
index ee3b922..2f8c5e6 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -36,6 +36,12 @@ services:
         # setup.sh sets this from the host, where the submodule resolves
         # correctly (git -C sso-manager-node rev-parse --short HEAD).
         GIT_COMMIT: ${SSO_GIT_COMMIT:-}
+        # Optional upstream HTTP(S) proxy for npm/apt during the build (NOT
+        # the theta42 "proxy" app). Set CFG_HTTP_PROXY in setup.env; empty by
+        # default, so this is a no-op unless configured.
+        HTTP_PROXY: ${CFG_HTTP_PROXY:-}
+        HTTPS_PROXY: ${CFG_HTTPS_PROXY:-}
+        NO_PROXY: ${CFG_NO_PROXY:-}
     container_name: sso-manager
     restart: unless-stopped
     networks: [theta-net]
@@ -58,6 +64,11 @@ services:
       - NODE_PORT=3001
       - LDAP_SERVER_ID=${LDAP_SERVER_ID:-}
       - LDAP_REPLICATION_HOSTS=${LDAP_REPLICATION_HOSTS:-}
+      # Optional upstream HTTP(S) proxy for outbound calls (SMTP, etc.) at
+      # runtime. See the build args above for the same setting during build.
+      - HTTP_PROXY=${CFG_HTTP_PROXY:-}
+      - HTTPS_PROXY=${CFG_HTTPS_PROXY:-}
+      - NO_PROXY=${CFG_NO_PROXY:-}
     volumes:
       # Operator-edited SSO secrets (sso-secrets.js). Read-WRITE so the bootstrap
       # can write the generated OAuth client creds into proxy-secrets.js. The
@@ -91,6 +102,11 @@ services:
         # setup.sh sets this from the host, where the submodule resolves
         # correctly (git -C proxy rev-parse --short HEAD).
         GIT_COMMIT: ${PROXY_GIT_COMMIT:-}
+        # Optional upstream HTTP(S) proxy for npm/apt during the build. See
+        # the sso-manager service above for details.
+        HTTP_PROXY: ${CFG_HTTP_PROXY:-}
+        HTTPS_PROXY: ${CFG_HTTPS_PROXY:-}
+        NO_PROXY: ${CFG_NO_PROXY:-}
     container_name: proxy
     restart: unless-stopped
     networks: [theta-net]
@@ -110,6 +126,11 @@ services:
       # not from env. NODE_ENV/NODE_PORT are process env the app reads directly.
       - NODE_ENV=production
       - NODE_PORT=3000
+      # Optional upstream HTTP(S) proxy for outbound calls (ACME/Let's
+      # Encrypt, DNS providers) at runtime.
+      - HTTP_PROXY=${CFG_HTTP_PROXY:-}
+      - HTTPS_PROXY=${CFG_HTTPS_PROXY:-}
+      - NO_PROXY=${CFG_NO_PROXY:-}
     volumes:
       # Operator-edited proxy secrets (proxy-secrets.js). READ-ONLY — the proxy
       # only reads it; the sso-manager bootstrap writes the OAuth creds. The
@@ -142,6 +163,11 @@ services:
       dockerfile: Dockerfile
       args:
         GIT_COMMIT: ${JUMP_GIT_COMMIT:-}
+        # Optional upstream HTTP(S) proxy for npm/apt during the build. See
+        # the sso-manager service above for details.
+        HTTP_PROXY: ${CFG_HTTP_PROXY:-}
+        HTTPS_PROXY: ${CFG_HTTPS_PROXY:-}
+        NO_PROXY: ${CFG_NO_PROXY:-}
     container_name: jump-host
     restart: unless-stopped
     networks: [theta-net]
@@ -153,6 +179,11 @@ services:
       - "${JUMP_WEB_BIND:-0.0.0.0}:${JUMP_WEB_PORT:-3002}:3002"  # web UI/API
     environment:
       - NODE_ENV=production
+      # Optional upstream HTTP(S) proxy for outbound calls (the directory API
+      # client) at runtime.
+      - HTTP_PROXY=${CFG_HTTP_PROXY:-}
+      - HTTPS_PROXY=${CFG_HTTPS_PROXY:-}
+      - NO_PROXY=${CFG_NO_PROXY:-}
     volumes:
       - ./config:/config:ro         # jump-secrets.js (written by ensure_config/bootstrap)
       - jump-data:/var/lib/jump-host  # generated host keys persist here
diff --git a/setup.env.example b/setup.env.example
index 2469fbb..5b32ca7 100644
--- a/setup.env.example
+++ b/setup.env.example
@@ -49,6 +49,19 @@ CFG_DOMAIN=example.com
 # under an OU-style prefix). Leave unset to use the DN built from CFG_DOMAIN:
 #CFG_BASE_DN=dc=example,dc=com
 
+# ── Optional outbound HTTP(S) proxy ──────────────────────────────────────────
+# For an isolated/offline/corporate-network test host that only reaches the
+# internet through an upstream HTTP proxy — NOT the theta42 "proxy" app.
+# Wired into every service's docker build (npm/apt) AND its running container
+# (SMTP, ACME/Let's Encrypt, DNS provider calls, the jump-host directory API
+# client). Leave unset to disable (the default); CFG_HTTPS_PROXY falls back to
+# CFG_HTTP_PROXY if unset, and CFG_NO_PROXY defaults to covering the stack's
+# own internal service names so container-to-container traffic never goes
+# through the proxy.
+#CFG_HTTP_PROXY=http://proxy.example.com:3128
+#CFG_HTTPS_PROXY=http://proxy.example.com:3128
+#CFG_NO_PROXY=localhost,127.0.0.1,sso-manager,proxy,jump-host
+
 # Optional — sensible defaults if left blank:
 #CFG_ORG=SSO Manager            # app display name + outbound email org
 #CFG_ADMIN_UID=admin            # initial SSO admin username
diff --git a/setup.sh b/setup.sh
index f6264b5..37d5a22 100755
--- a/setup.sh
+++ b/setup.sh
@@ -165,6 +165,22 @@ export CFG_JUMP_HOST_ENABLED CFG_JUMP_HOST
 # When enabled, activate the compose profile so `up`/`ps` include the service.
 if [[ "$JUMP_ENABLED" == "1" ]]; then export COMPOSE_PROFILES="jump-host"; fi
 
+# ── Optional outbound HTTP(S) proxy for docker build + the running containers ─
+# CFG_HTTP_PROXY / CFG_HTTPS_PROXY / CFG_NO_PROXY (from ./setup.env or the
+# environment) — NOT the theta42 "proxy" app; this is an upstream HTTP proxy
+# for reaching the internet (npm/apt during image builds, and SMTP/ACME/DNS
+# provider calls at runtime), useful on isolated/offline/corporate-network
+# test hosts. Off by default. docker-compose.yml passes these through as both
+# build args (Docker also recognizes them as predefined build ARGs) and
+# container environment on every service, so one setup.env entry covers the
+# whole stack.
+export CFG_HTTP_PROXY="${CFG_HTTP_PROXY:-}"
+export CFG_HTTPS_PROXY="${CFG_HTTPS_PROXY:-${CFG_HTTP_PROXY:-}}"
+export CFG_NO_PROXY="${CFG_NO_PROXY:-localhost,127.0.0.1,sso-manager,proxy,jump-host}"
+if [[ -n "$CFG_HTTP_PROXY" ]]; then
+	info "Using HTTP proxy for docker build + containers: $CFG_HTTP_PROXY"
+fi
+
 # ── 1. Update submodules to their latest release tag, verify build contexts ───
 # Submodules track release tags (vX.Y.Z), not the tip of master -- so
 # "update" means "move to the newest tag", not "move to the newest commit".