Srx Dynamic Ip Feed

SRX Dynamic IP Feed Servers

Overview

SRX dynamic IP objects let Junos periodically download IPv4/IPv6 entries from an HTTPS feed server and expose those entries as address objects usable in security policies. This is useful when rule structure is stable but source or destination addresses change frequently through automation, threat intelligence, cloud inventory, orchestration systems, or allow/block lists.

The key SRX idea is:

1. The web server hosts a bundle archive, typically .tgz.
2. Inside the archive are feed files, each containing IPs/prefixes/ranges.
3. security dynamic-address feed-server <server> points to the archive URL.
4. feed-name <name> path <path-inside-archive> maps a feed to a file in the archive.
5. security dynamic-address address-name <object> profile feed-name <feed> exposes the feed as a policy address object.
6. Policies reference the dynamic address name as source or destination address.

SRX checks feed freshness with HTTP HEAD, downloads changed archives with GET, and updates dynamic objects without a commit. The default update interval is 5 minutes; the minimum is 30 seconds. Use production TLS validation and authentication whenever possible.

Scope and routing

Use this skill for self-hosted dynamic-address feeds. Use srx-policy for Juniper SecIntel or ATP feeds and parsing-srx-configs for full-config extraction.

Runtime intake

Use this skill only for feed-server dynamic address objects. Use parsing-srx-configs for full-config extraction and srx-policy when the policy match itself is in question. Before acting, inspect the request, artifacts, and approved read-only evidence. If unresolved facts materially change safety, scope, correctness, confidence, or output, read references/runtime-intake.md. For each unresolved material fact whose catalog condition is true, invoke Claude AskUserQuestion or Codex request_user_input before continuing or issuing an open-ended request. Ask at most three single-select catalog questions per round. After each response, ask another round whenever any unresolved material catalog condition remains true; continue only when none remain. Do not repeat answered questions or show the full catalog. Without a native tool, present each selected catalog question with its 2-3 labeled choices and a free-text Other path in concise plain text; do not substitute a generic checklist. Never request secrets or unredacted customer data. Answers are context, not live-change approval; obtain separate explicit approval before configuration, commit, upgrade, reboot, delete, or failover.

Prerequisites and Version Notes

• SRX/vSRX running Junos with security dynamic-address feed support.
• A reachable HTTPS server that supports HEAD and GET against the feed archive URL.
• Feed archive in a format supported by Junos. This skill focuses on bundle archive .tgz mode.
• Feed file contents can include:
  • single IPs: 192.0.2.1, 2001:db8::1
  • prefixes: 192.0.2.32/28, 2001:db8:1::/64
  • ranges: 192.0.2.5-192.0.2.20, 2001:db8::5-2001:db8::20
• Junos 25.2 or later is required for the simple SRX username/password authentication feature described here.
• For production, prefer DNS/hostname feed URLs with certificate validation. If using static host mapping, ensure the hostname in the URL matches the certificate CN or SAN when certificate attribute validation is enabled.

Feed Archive Layout

Use one directory per archive and one file per feed. Example:

cd /var/www/html
mkdir feed-1
printf '1.1.1.1\n' > feed-1/whitelist-1
printf '2.2.2.2\n' > feed-1/blacklist-1
tar czf feed-1.tgz feed-1/

The SRX maps the archive contents by path:

feed-1.tgz
└── feed-1/
    ├── whitelist-1
    └── blacklist-1

SRX feed-name mapping:

set security dynamic-address feed-server debian-1 feed-name whitelist-1 path feed-1/whitelist-1
set security dynamic-address feed-server debian-1 feed-name blacklist-1 path feed-1/blacklist-1

Then expose each feed as a dynamic policy object:

set security dynamic-address address-name whitelist-1 profile feed-name whitelist-1
set security dynamic-address address-name blacklist-1 profile feed-name blacklist-1

Lab-Grade HTTPS Feed Server

Use this only for labs because it does not validate the server certificate on SRX.

On Debian with nginx:

apt install nginx-light ssl-cert
make-ssl-cert generate-default-snakeoil

Enable the SSL listener in /etc/nginx/sites-enabled/default:

listen 443 ssl default_server;
listen [::]:443 ssl default_server;
include snippets/snakeoil.conf;

Restart and test:

systemctl restart nginx
openssl s_client -connect localhost:443

Create a feed archive:

cd /var/www/html
mkdir feed-1
printf '1.1.1.1\n' > feed-1/whitelist-1
printf '2.2.2.2\n' > feed-1/blacklist-1
tar czf feed-1.tgz feed-1/
tail -f -n0 /var/log/nginx/access.log

SRX lab configuration:

set security dynamic-address feed-server debian-1 url https://10.0.0.10/feed-1.tgz
set security dynamic-address feed-server debian-1 update-interval 60
set security dynamic-address feed-server debian-1 hold-interval 604800
set security dynamic-address feed-server debian-1 feed-name whitelist-1 path feed-1/whitelist-1
set security dynamic-address feed-server debian-1 feed-name blacklist-1 path feed-1/blacklist-1
set security dynamic-address address-name whitelist-1 profile feed-name whitelist-1
set security dynamic-address address-name blacklist-1 profile feed-name blacklist-1

Commit and verify. The nginx access log should show an initial GET, then periodic HEAD probes. When the archive changes, SRX should perform another GET.

Production Pattern: Validate the Feed Server Certificate

Production feed servers should use a certificate issued by a CA trusted by the SRX, and the SRX should validate that the certificate identity matches the URL hostname.

Server Side

Generate or obtain:

• CA certificate, e.g. IPFD_CA
• server certificate/key for the feed server hostname, e.g. debian-2

Install the server cert/key and CA certificate for nginx:

cp CA/cacert.pem /etc/ssl/certs/IPFD_CA.pem
cp CA/debian-2-cert.pem /etc/ssl/certs/
cp CA/debian-2-key.pem /etc/ssl/private/
chmod 600 /etc/ssl/private/debian-2-key.pem

Configure nginx SSL snippet, e.g. /etc/nginx/snippets/IPFD.conf:

ssl_certificate /etc/ssl/certs/debian-2-cert.pem;
ssl_certificate_key /etc/ssl/private/debian-2-key.pem;

Enable it in the site:

listen 443 ssl default_server;
listen [::]:443 ssl default_server;
include snippets/IPFD.conf;

Restart:

systemctl restart nginx
openssl s_client -connect localhost:443

Create the production archive:

cd /var/www/html
mkdir feed-2
printf '10.1.1.1\n' > feed-2/whitelist-2
printf '10.2.2.2\n' > feed-2/blacklist-2
tar czf feed-2.tgz feed-2/
tail -f -n0 /var/log/nginx/access.log

SRX Side

Configure and load the CA profile:

set security pki ca-profile IPFD_CA ca-identity IPFD_CA revocation-check disable

Then load the CA certificate after uploading it to the SRX:

request security pki ca-certificate load ca-profile IPFD_CA filename cacert.pem
request security pki ca-certificate verify ca-profile IPFD_CA

Configure hostname resolution if DNS is not available:

set system static-host-mapping debian-2 inet 10.0.1.10

Configure the SSL initiation profile and feed server:

set services ssl initiation profile srx-1_IPFD_CA trusted-ca IPFD_CA
set security dynamic-address feed-server debian-2 url https://debian-2/feed-2.tgz
set security dynamic-address feed-server debian-2 update-interval 60
set security dynamic-address feed-server debian-2 hold-interval 86400
set security dynamic-address feed-server debian-2 tls-profile srx-1_IPFD_CA
set security dynamic-address feed-server debian-2 validate-certificate-attributes subject-or-subject-alternative-names
set security dynamic-address feed-server debian-2 feed-name whitelist-2 path feed-2/whitelist-2
set security dynamic-address feed-server debian-2 feed-name blacklist-2 path feed-2/blacklist-2
set security dynamic-address address-name whitelist-2 profile feed-name whitelist-2
set security dynamic-address address-name blacklist-2 profile feed-name blacklist-2

Important: with validate-certificate-attributes subject-or-subject-alternative-names, the hostname in the URL must match the server certificate CN or SAN. A URL like https://debian-3/feed-2.tgz against a certificate for debian-2 should fail.

Optional: HTTP Basic Authentication

Requires Junos 25.2R1 or later for SRX client username/password feed authentication.

On nginx, enable basic auth for the relevant location:

location / {
    auth_basic "Restricted Area";
    auth_basic_user_file /etc/nginx/htpasswd;
    # existing content serving configuration
}

Create credentials:

apt install apache2-utils
htpasswd -c -b /etc/nginx/htpasswd srx <feed-basic-auth-password>
systemctl restart nginx

Before SRX credentials are configured, expect HTTP 401 errors in ipfd logs:

failed<http return error code 401>

Add credentials to the SRX feed server:

set security dynamic-address feed-server debian-2 user-name srx
set security dynamic-address feed-server debian-2 password <feed-basic-auth-password>

Use a secure password management workflow for production. Avoid leaving cleartext credentials in tickets, chat, or documentation.

Optional: Mutual TLS Client Certificate Authentication

Use mutual TLS when the feed server should only serve feed archives to authenticated SRX clients.

On nginx, configure a trusted client CA and enforce client certificate success inside a location:

ssl_client_certificate /etc/ssl/certs/IPFD_CA.pem;
ssl_verify_client optional;

location / {
    if ($ssl_client_verify != SUCCESS) {
        return 403;
    }
    # existing content serving configuration
}

Without the SRX client cert, expect HTTP 403 errors in ipfd logs:

failed<http return error code 403>

Upload the SRX client certificate and key to SRX, then load and verify:

request security pki local-certificate load certificate-id srx-1_IPFD_CA filename srx-1-cert.pem key srx-1-key.pem
request security pki local-certificate verify certificate-id srx-1_IPFD_CA

Reference the client certificate from the SSL initiation profile:

set services ssl initiation profile srx-1_IPFD_CA client-certificate srx-1_IPFD_CA

After commit, successful downloads should resume.

Applying Dynamic Objects in Security Policies

Dynamic address names become policy address objects and can be used as source or destination criteria.

Example blocklist policy:

set security policies from-zone trust to-zone untrust policy block-dynamic-bad-dst match source-address any
set security policies from-zone trust to-zone untrust policy block-dynamic-bad-dst match destination-address blacklist-1
set security policies from-zone trust to-zone untrust policy block-dynamic-bad-dst match application any
set security policies from-zone trust to-zone untrust policy block-dynamic-bad-dst then deny
set security policies from-zone trust to-zone untrust policy block-dynamic-bad-dst then log session-init

Example allowlist policy:

set security policies from-zone trust to-zone untrust policy permit-dynamic-good-dst match source-address any
set security policies from-zone trust to-zone untrust policy permit-dynamic-good-dst match destination-address whitelist-1
set security policies from-zone trust to-zone untrust policy permit-dynamic-good-dst match application junos-http
set security policies from-zone trust to-zone untrust policy permit-dynamic-good-dst then permit
set security policies from-zone trust to-zone untrust policy permit-dynamic-good-dst then log session-init
set security policies from-zone trust to-zone untrust policy permit-dynamic-good-dst then log session-close

Policy ordering still matters. Put deny/reject blocklist policies above broader permit policies when the blocklist must take precedence.

Session Scan Tunable

SRX can reconcile existing sessions when addresses are added to dynamic feeds. Enable:

set security dynamic-address session-scan

Important behavior:

• Session scan works for policies with deny or reject action.
• It is useful when a newly added blacklist address should affect existing sessions.
• Removing an address from an allowlist does not automatically kill existing sessions by itself. If immediate teardown behavior is needed, add the address to a deny/reject feed at least temporarily so a deny/reject policy can match.

A common structure is:

1. reject-http or deny-bad policy matching blacklist-1
2. permit policy matching whitelist-1
3. final deny policy for everything else

Routing Instance Reachability

Warning — non-default feed-server routing-table pins are not reboot-safe on vSRX 24.4R1.9. A saved configuration containing security dynamic-address feed-server <server> routing-table <instance>.inet can commit and fetch normally after the table already exists, yet fail normal boot validation with routing table <instance>.inet cannot find. The device can then activate Recovery Mode and load its rescue configuration. A successful interactive commit is not reboot-safety proof; this failure was field-observed on 18 devices.

Preferred reboot-safe path: make the feed server reachable through the default routing instance and omit the feed-server routing-table statement. On the affected release, devices using the same feed server without the pin booted normally.

For diagnosis only, the interactive syntax was live-verified as <instance>.inet, without the normal trailing .0; <instance>.inet.0 and inet.0 were rejected, while bare inet and <instance>.inet were accepted. Committing the routing instance first only satisfies the interactive commit dependency; it does not make the saved configuration boot-safe.

event-options is an unsupported/unverified workaround for this defect. Juniper documents that an event policy can change and commit configuration, but not a supported boot trigger/order that waits for this routing table and avoids persisting the pin into the next boot. Do not present it as reboot-safe without a Juniper-confirmed procedure for the exact platform/release and controlled cold-boot validation with console and rollback protection.

Juniper documents the Recovery Mode banner, UI_DEVICE_IN_RECOVERY_MODE, and that immediately after recovery rollback 1 contains the failed configuration in Rescue and Recovery of Configuration File.

Verification Commands

After commit, check feed-server and feed status:

show security dynamic-address summary

Look for:

• server name and URL
• update interval and hold interval
• TLS profile and user name fields
• feed names mapped to dynamic address names
• total IPv4/IPv6 entries
• download/db/other error counters
• next update and expiration times
• last update status

List loaded dynamic address records:

show security dynamic-address

Check feed downloader logs:

show log messages | match ipfd

Expected successful log patterns include:

IPFD_DA_FEED_HTTPS_STATUS: Feed(<feed>) download data(<url>) status (succeeded)
IPFD_DA_FEED_HTTPS_STATUS: Feed(<feed>) download data(<url>) status (succeeded<file not changed>)

On the web server, tail access logs:

tail -f -n0 /var/log/nginx/access.log

Expected web access pattern:

GET /feed-1.tgz HTTP/1.1 200
HEAD /feed-1.tgz HTTP/1.1 200
HEAD /feed-1.tgz HTTP/1.1 200

When the archive changes, expect a HEAD followed by a GET.

Update Test Procedure

Read references/feed-update-test.md when validating that feed changes propagate without a configuration commit.

Troubleshooting Matrix

Common Pitfalls

1. Using IP URLs in production with certificate validation. Certificate identity validation needs a hostname that matches the certificate CN/SAN. Use DNS or system static-host-mapping and put the hostname in the feed URL.

2. Forgetting that feed-name path is the path inside the archive. If the archive contains feed-1/blacklist-1, configure that full path, not only blacklist-1.

3. Updating feed files but not recreating the .tgz. SRX downloads the archive URL, not the loose files. Re-run tar czf feed-X.tgz feed-X/ after changing contents.

4. Assuming removal from an allowlist kills sessions. Dynamic address updates affect policy matching, but existing sessions may persist. Use session scan plus deny/reject feed design where immediate teardown is required.

5. Setting too aggressive update intervals without considering server and fleet load. The minimum can be 30 seconds, but many SRXs polling many feeds can create avoidable server load.

6. Treating lab TLS as production TLS. A self-signed server without SRX validation is useful for proving feature behavior, not for production security.

7. Using revocation-check disable without understanding risk. The demo disables revocation checking for simplicity. Production PKI should explicitly decide CRL/OCSP behavior.

8. Leaking feed-server credentials. SRX basic auth passwords and private keys should not be pasted into chat/logs/tickets. Use redaction and credential-handling practices.

9. Treating an interactive commit as reboot-safety proof. A non-default feed-server routing-table pin can commit and operate normally but still trigger Recovery Mode at the next boot. Prefer default-instance reachability and omit the pin.

Verification Checklist

• Feed archive URL is reachable from the SRX routing context.
• Web server returns HTTP 200 for GET and HEAD against the archive URL.
• Archive contains expected paths: tar tzf feed-X.tgz.
• feed-name <name> path <archive/path> matches archive contents exactly.
• address-name <object> profile feed-name <feed> exists for every policy object.
• TLS CA profile is loaded and verified when certificate validation is used.
• URL hostname matches server certificate CN/SAN when certificate attribute validation is enabled.
• Basic auth credentials or client certificate are configured if the server requires them.
• show security dynamic-address summary shows zero download errors and expected entry counts.
• show security dynamic-address shows expected IPs/prefixes/ranges.
• Policies reference dynamic address names in correct source/destination fields and correct order.
• show log messages | match ipfd shows succeeded or succeeded.
• Server logs show expected GET/HEAD behavior.
• Update test confirms changed archive contents appear without commit.
• Persistent configuration omits non-default feed-server routing-table <instance>.inet; a successful interactive commit and healthy feed are not reboot-safety proof.
• Any exception is recorded as unsupported/unverified until Juniper confirms the exact platform/release procedure and a controlled lab cold boot passes with console and rollback protection; never validate first in production.

Source

This skill is a condensed, operationalized SRX playbook based on Karel Hendrych's Juniper Community TechPost, “SRX Dynamic IP Objects aka Feed-server,” published 2025-11-30:

https://community.juniper.net/blogs/karel-hendrych/2025/11/30/srx-dynamic-ip-objects-aka-feed-server

An independently written Inspired by note is stored at references/source-extract.md; it preserves attribution and verification implications without reproducing the TechPost.