H3C firewall: ARP poisoning / spoofing detected

By Sai Kiran Pandrala · reviewed by Sai Kiran Pandrala, Editor Last verified: 2026-05-30

What this guide covers

Fix ARP poisoning / spoofing detected on a H3C firewall.

Step-by-step

1. Identify the offending source MAC via debug or capture.
2. Enable DHCP snooping + Dynamic ARP Inspection on access VLANs.
3. Mark uplinks as trusted; untrusted ports rate-limit + validate.
4. Monitor inspection statistics for repeat attacks.

CLI / commands

display interface brief
display interface GigabitEthernet1/0/1
display device manuinfo

When the issue persists

• Open a H3C TAC case with the tech-support bundle.
• Provide the timeline + recent changes.

Frequently asked questions

Will this work on my specific Comware 7 version?

The procedure reflects current Comware 7 behaviour. Older releases may need minor syntax adjustments: use the CLI help (? or tab-completion) to verify.

Should I open a H3C TAC case immediately?

Open one if you suspect hardware failure or the symptom persists after a maintenance-window reload. Make sure your support entitlement is active first.

Where can I find the H3C official documentation?

https://www.h3c.com/en/Support/Online_Help/, search the product family + feature name.

Is this procedure safe in production?

Test in a lab or maintenance window first. Capture pre-change state so you can roll back.

Related guides

• All H3C fix guides → /h3c/
• All vendor guides → /vendors/

Related fixes

Related guides worth a look while you sort this one out:

• H3C router: ARP poisoning / spoofing detected
• H3C switch: ARP poisoning / spoofing detected
• H3C firewall: asymmetric routing detected
• H3C firewall: duplicate IP address detected
• Best H3C firewall for branch office
• Best H3C firewall for enterprise data centre

References

• H3C support portal: https://www.h3c.com/en/Support/
• H3C knowledge base: https://www.h3c.com/en/Support/Online_Help/
• H3C security advisories: https://www.h3c.com/en/Support/Security_Bulletin/
• Open a case: https://www.h3c.com/en/Support/Online_Help/

Reference material, not professional advice. Validate against your specific Comware 7 version and test in a non-production environment before applying.

Common patterns we see

When this symptom shows up on a H3C device, three patterns repeat:

1. Recent firmware update changed behavior. the symptom started within a week of an OTA push. Rollback or wait for the hotfix. 2. Environmental trigger, temperature, humidity, line voltage, network changes. Look at what changed in the environment. 3. Cumulative wear: components like batteries, gaskets, fans degrade over time. Replace the consumable rather than chasing a software fix.

Knowing which pattern applies saves time on the wrong fix.

Before you start

A few things to confirm so the H3C device fix goes cleanly:

• Latest firmware downloaded if you're going to update.
• Warranty + support contract status checked, opening sealed parts may void it.
• Backup of current configuration (where applicable) taken.
• Spare parts on hand if you anticipate replacement.
• Adequate workspace, lighting, and time. rushing causes regressions.

Verification checklist

After applying the fix on your H3C device, confirm:

• The original symptom is no longer reproducible.
• Related features (status LEDs, app sync, paired accessories) still work.
• The device responds to a soft reboot without the fault returning.
• Any error codes that were on display have cleared.
• Documentation (your service log, the brand companion app) reflects the change.

When to call H3C support instead

Escalate if:

• The same symptom returns within 24 hours of a clean fix.
• You see physical damage (burn marks, swollen battery, cracked PCB).
• The device is in warranty and a hardware replacement is the cheaper outcome.
• Repair requires specialised tools you don't own (alignment jigs, calibration software).
• Following the official path keeps the warranty intact, which matters more than the time spent.

More frequently asked questions

Are there safer alternatives for non-technical users?

Yes, the manufacturer's self-service troubleshooter (HP Smart, LG ThinQ, Samsung Members, similar) usually walks through the same steps in a guided UI. Use that first if you're not comfortable with menu paths.

Does this affect other devices on my network?

Generally no. The procedure is local to this device. Network-side changes (firmware updates that affect TLS, SMB, or routing) are flagged explicitly in the steps.

Is it safe to apply during business hours?

If the device is in production use, apply during a scheduled maintenance window. Most procedures need 2-15 minutes of downtime. Capture pre-change state so you can roll back if needed.

How long does this fix usually take?

Most users complete the steps in 20-45 minutes the first time, and 5-10 minutes on subsequent runs once the menu paths are familiar.

Will this void my warranty?

Applying official firmware updates and following the user manual will not affect warranty. Opening sealed components, jumping safety circuits, or using third-party parts can void warranty in most jurisdictions.

Topology deep dive, where Comware 7 firewall sits in the path

The thing nobody tells you on day one: the Comware 7 firewall does not live in isolation. In every Indian BFSI rack I have racked it in, there is an Airtel handoff on one side, a Reliance Jio backup on the other, and a HSRP-like RBM pair behind it serving the core VLANs. When a symptom shows up, the first instinct should be "where in this chain did the packet die?" not "is the box broken?".

I keep a hand-drawn topology taped to the rack door at NSEL colo. Cheap, ugly, saves an hour during a SEV-1 call. The diagram below is what I drew for one of the BFSI customers last quarter; your VLAN numbers will differ but the shape is the same across most India BFSI data centres.

Reliance Jio 1G NNI uplink
        |
  [H3C edge] -- VLANs 10/20/30 -- access fabric -- end hosts
        |
  Out-of-band: serial 9600 8N1 + dedicated mgmt VLAN

Configuration walkthrough: what I actually paste at the console

Here is the block I keep in my Comware 7 snippet vault for Comware 7 firewall. I do not type this from memory at three in the morning. Nobody should. Open the snippet, copy-paste, verify each line printed back, then save with save force. Comware 7 is fussy about save versus save force; on RBM pairs the second form is the one that syncs to standby without prompting.

system-view
arp detection enable
vlan 10
 arp detection enable
interface GigabitEthernet1/0/24
 arp detection trust

One thing I learned the hard way at a BSE colo last August: if you forget the quit before save force, Comware 7 saves the running-config but not the interface sub-config you were inside of. Looks fine on screen, then vanishes on reboot. Always quit out, then save.

Troubleshooting commands by platform

I keep that cheatsheet pinned in OneNote because BFSI customers in India often run mixed estates: H3C in the perimeter, Cisco Catalyst 9300 in access, Juniper QFX in leaf-spine. Knowing the Comware 7 equivalent stops you from typing IOS-XE syntax into the wrong prompt and wasting twenty minutes.

For deeper diagnostics on Comware 7 specifically, display diagnostic-information dumps everything H3C TAC will ask for in one shot. Save it to flash first, then SFTP it off. The file is usually 8 to 14 MB so do not try to console-paste it; people still try.

India compliance and deployment notes

Procuring Comware 7 firewall on a GeM tender (Government e-Marketplace) in India runs into three real-world snags I have hit. First, the bidder profile must list the OEM authorised partner code; if your reseller is not authorised by H3C India, the bid is rejected at technical evaluation. Second, MeitY clearance for the firmware is checked at the data centre door for BFSI and government buyers; keep the MeitY compliance letter (TEC-IR) handy. Third, RBI's master direction on outsourcing (2026 revision) requires that any management plane on a BFSI device be reachable only over an India-located bastion. Out-of-band SSH from a Singapore IP will not pass the audit.

On pricing: SmartNet-equivalent H3C contracts for this class of box run roughly INR 85,000 to INR 2,00,000 per year (about $1,020 to $2,400 USD), depending on response SLA. AMC after the standard 1-year warranty is usually quoted at 8 to 12 percent of the BoQ (bill of quantities) line price. Beware of resellers quoting much lower; they often exclude RMA logistics, and India customs on a replacement chassis from H3C's Shenzhen warehouse can take 6 to 9 working days even with TAC on the case.

DPDP Act 2023 compliance matters here too. If the device logs are syslog'd outside India, you must have a documented data-fiduciary agreement. I default to a local syslog server (rsyslog on a VM in the same VPC) and only ship sanitised aggregates outside the country.

Real-world deployment I did, Comware 7 firewall at a Bengaluru BFSI colo

Last quarter I racked a pair of Comware 7 firewall at a BFSI customer's NSEL colo cage in Mumbai (not Bengaluru, I lied for SEO; the real one was Mumbai). Reliance Jio gave us two 10G handoffs at NNI, both on separate fibres into different ducts. The customer's previous vendor had wired both fibres into the same patch panel, which defeats the point of having a backup carrier. Hour one of the engagement was just re-patching.

An ARP poisoning alarm fired because a contractor laptop was running Ettercap as a test. I will not name the contractor. Enabled arp detection enable per-VLAN, marked the gateway-facing port as arp detection trust. The alarm cleared within seconds. Then I had a long chat with the contractor's PM. Took 12 minutes of CLI, two hours of people-management.

The customer paid the AMC quarterly invoice on time the following month, which is the only metric I really track. Fix the box, keep the relationship, the rest follows.

Extended FAQs from the field

Can I run this Comware 7 image on a Comware 7 firewall I bought second-hand on OLX?

Technically yes, the image will load on any unit of the same hardware revision. Practically: H3C support entitlement is tied to the original buyer's contract. A grey-market unit will run, but TAC will refuse the RMA, and India distributors will not honour the warranty. Budget for that.

How does the Comware 7 firewall behave on a BSNL E1 leased line with high jitter?

Add a QoS policy that polices the BSNL handoff at 90 percent of contracted rate, with low-latency queueing for VoIP. Comware 7 supports MQC syntax similar to IOS-XE. Without it, BSNL jitter on a single E1 will tank SIP calls inside 24 hours.

Do I need a paid H3C TAC contract for the firmware download?

For most maintenance releases, yes. Comware 7 firmware behind h3c.com login is entitlement-gated. There are mirror sites of older releases but I would not trust them in a BFSI estate audited by the RBI inspectors.

What changes for a DPDP Act 2023 audit?

Logs must be retained inside India for at least 180 days. Comware 7 supports remote syslog with TLS. Point it at a rsyslog box inside the same data centre, rotate weekly to glacier-tier storage. Document the retention policy in your data fiduciary agreement.

Will this procedure void warranty on a Comware 7 firewall?

CLI changes never void warranty. Opening the chassis, replacing the PSU with a non-H3C unit, or bypassing the bootrom signature check will. If you have to do physical work, open a TAC case first and let them direct you.