# PortKnock > iPhone port knocking utility for network administrators to secure server access. (iPhone/iPad app by Danny Sung.) - Source: https://appshunter.io/ios/app/portknock/id358353536 (this page in markdown: same URL + `.md`) - Developer: [Danny Sung](https://appshunter.io/developer/1555969244) - Category: Utilities - Price: $0.99 - Rating: 5.00/5 from 9 App Store ratings · 25 written reviews indexed - Age rating: 4+ - Requires: iOS 12.0 · 11 MB - Languages: American English - Released: 2010-03-11 - Data updated: 2026-08-24 - Monetization: paid - User reviews in markdown: https://appshunter.io/ios/app/portknock/id358353536/reviews.md ## What is PortKnock? -- Overview -- This application is a simple port knocker for the iPhone, generally useful only to network administrators. You *must* have a port knock daemon running on your server for this application to be useful. Features in this version of Port Knock: - Password Protection - Knock Validation - Import/Export Hosts - Auto App Launcher(+) - Knock Progress Screen - Shows your External IP Address - Arbitrary number of ports per host - An unlimited number of host definitions - TCP/UDP configuration per port - Selectively sending knocks through WiFi or Carrier/3G networks - Configurable interpacket delay - Has no advertising -- Use Cases -- This app is ideal if you're on a WiFi network but don't have a port knocker on the available computers. If you're sitting behind a NAT, the iPhone/iPod Touch will have the same IP as any of the other computers on your network. This is also great to use with TouchTerm or any other ssh or telnet software for the iPhone.Just give it the hostname and a list of ports, and whether you want it to send TCP or UDP packets. -- Brief Description of Port Knocking for the Layman -- Port Knocking is a technique to secure services behind a firewall until a specific knock sequence is given. This is not to be confused with port scanning (a network management tool for discovering open services on a system). Imagine you left your kids at home alone. You don't want them to open the door for strangers. And when a stranger comes knocking, you don't even want them to come to the door, because you don't want them to know your kids are there. But, when you or other family members come, you might want them to open the door for you. So you teach them to listen for a certain rattat-tat-tat or special knock that only you and your family know. This is the same concept you can apply to your servers. If you run a knock daemon on your server, this app then lets you send the special knock to it. A more technical description of port knocking can be found on Wikipedia: http://en.wikipedia.org/wiki/Port_knocking -- Additional Info -- If you're in need of a knock server, I personally use Judd Vinet's knock daemon for linux. It's quite easy to use: http://www.zeroflux.org/projects/knock You can find of information and a nice list of other knock clients and servers over at http://www.portknocking.org/ -- Notes -- + There are some restrictions regarding the Auto App Launcher. For SSH, you can only create temporary connections. For Mail, you will always be shown a new compose mail window first. Unfortunately, this is due to the way App integration works on iOS. There's not much I can do to address these issues at this time. -- Support -- For better support, please send bug reports and feature requests to danny@sungheroes.com, rather than simply posting it in a review. You can find more info on using PortKnock at the main website: http://www.sungheroes.com/products/portknock-iphone/ -- History -- 2022-02-28 PortKnock 4.18 released. LaunchApp automatically works again. Fixed some import bugs. 2018-01-xx PortKnock 4.12 supports IPv6 2017-09-xx PortKnock 4.0 released for iOS 10.3 2013-02-15 PortKnock 3.2 should work again on iOS5 2011-Jul-10 PortKnock 3.0.833 released. Added password protection, knock validation, import/export hosts, auto app launcher, and knock progress screen. 2010-Dec-14 PortKnock 2.02 released. Added a 'copy hosts' feature. Host/Port reordering should now work correctly. Entry fields should now work properly on iOS 4.2.1. 2010-Sep-25 PortKnock 2.01 is now available in the app store. iPhone 4's should no longer have an issue. If you are experiencing problems, please email me. 2010-Sep-09 The iPhone4 issue should be resolved. A bug fix release has been submitted. Thank you all for your patience! ## Key features - Password Protection - Knock Validation - Import/Export Hosts - Auto App Launcher - Shows External IP Address - TCP/UDP Configuration ## Recent user reviews (10 of 25) All indexed reviews: https://appshunter.io/ios/app/portknock/id358353536/reviews.md ### 1/5 — it's not same with knock on ports on android *2026-04-10* Knock on ports on android can setup sequence steps to knock the port, but this app can not do it ### 5/5 — Does what it says and the price is nice *2025-12-19* I got tired of opening my laptop to knock any time I got to a new place. Now I can knock from my phone and connect without the extra steps. 99 cents and it’s a no brainer. No ads, no crapware, it just works ### 5/5 — Great for DevOps *2024-09-07* Thank you for this great tool. Using this tool I was able to secure my server ports even more! I really suggest every devops engineer to setup port knocking on their SSH port. ### 5/5 — Does port knocking well *2023-03-03* Simple and does exactly what I need to unlock my network services ### 1/5 — Total garbage *2019-08-17, version 4.13* Looks and runs like it was written in an afternoon. Not user friendly at all. No guidance. No progress explanation. Oh and we use port knocking for all our servers so I'm not new to this. Learn from my lesson and save your money. ### 5/5 — Fantástico - Fantastic APP *2018-07-15, version 4.13* Fantastic APP to tecnology professional. ### 5/5 — Straightforward app, with right features and engaged developer *2018-03-13* It works, it does what you want, and the developer is friendly and helpful if you find a bug. ### 5/5 — Finally *2018-01-08* Finally, a port knock client that works on iOS. ### 4/5 — Glad I found this *2016-07-03, version 3.3* Just recently setup knockd on my vps and didn't think to check if there was an iOS app. Luckily there is and it works on ios9. When switching between wifi and 3G it did have problems picking up my 3G but closing and reopening fixed this. Would be nice if the graphics could be updated to suite ios9 better, other than it works great. ### 5/5 — Works well *2015-03-03* Having used the app for several weeks and on several servers I am very happy. I never have to repeat the knock sequence and haven't found any bugs. ## Frequently asked questions about PortKnock ### What is PortKnock used for? PortKnock is a utility for network administrators to send specific port knock sequences to a server. This technique secures services behind a firewall until the correct sequence is received. ### Does PortKnock have ads? No, PortKnock does not contain any advertising, providing an uninterrupted user experience. ### What devices does PortKnock support? PortKnock is available for iPhone, iPad, and iPod Touch devices. ### How much does PortKnock cost? PortKnock is a paid application, priced at $0.99. ### What is the age rating for PortKnock? PortKnock has an age rating of 4+, making it suitable for a wide audience. ### How often is PortKnock updated? The latest version of PortKnock was released on March 1, 2022, indicating recent development and support. ### Can I manage multiple hosts with PortKnock? Yes, PortKnock allows for an unlimited number of host definitions and supports an arbitrary number of ports per host. ### What are the limitations of the Auto App Launcher in PortKnock? The Auto App Launcher has some restrictions for SSH (only temporary connections) and Mail (always opens a new compose window first) due to iOS integration limitations. ## Version history (last 5 releases) ### 4.18 — 2022-03-01 Various bug fixes. LaunchApp should now work correctly. Fixes some import bugs. Rearranged knock editing screen for clarity. ### 4.16 — 2021-01-20 Support for IPv6 destinations. Added iPhone X support. Also some minor bug fixes and UI improvements. ### 4.13 — 2018-05-03 Support for IPv6 destinations. Added iPhone X support. Also some minor bug fixes and UI improvements. ### 4.11 — 2017-12-11 Added iPhone X support. Also some minor bug fixes and UI improvements. ### 4.0 — 2017-09-16 Entirely refreshed for iOS 10. Added iPad support. It is no longer possible to manually configure the network interface, however it will automatically use what is available (WiFi or cellular). If you have any issues, please contact me: danny@sungheroes.com ## Apps similar to PortKnock | App | Rating | Price | Category | | --- | --- | --- | --- | | [VoIP.ms Softphone: Call & Text](https://appshunter.io/ios/app/voipms-softphone-call-and-text/id6748383110) | 3.4 (15) | Free | Utilities | | [RustDesk Remote Desktop](https://appshunter.io/ios/app/rustdesk-remote-desktop/id1581225015) | 4.1 (73) | Free | Utilities | | [ZeroTier One](https://appshunter.io/ios/app/zerotier-one/id1084101492) | 3.9 (189) | Free | Utilities | | [MikroTik Back To Home](https://appshunter.io/ios/app/mikrotik-back-to-home/id6450679198) | 4.8 (6) | Free | Utilities | | [Network Analyzer Pro: IP Tools](https://appshunter.io/ios/app/network-analyzer-pro-ip-tools/id557405467) | 4.8 (9,059) | $3.99 | Utilities | | [Ping - network utility](https://appshunter.io/ios/app/ping-network-utility/id576773404) | 4.3 (376) | Free | Utilities | ## More apps by Danny Sung - [Step In Time](https://appshunter.io/ios/app/step-in-time/id775682586) - [Music Stitcher](https://appshunter.io/ios/app/music-stitcher/id1614083828) All apps by Danny Sung: https://appshunter.io/developer/1555969244 --- *Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-08-24.*