I am supporting development of a client application that will be communicating to a seperate enterprise service bus. We have our own black box services to develop against. We each host multiple REST endpoints (using RESTeasy) to communicate.
One scenario we need to demonstrate to our client is sudden loss of network connectivity between my client application and their ESB with later network restoration. In the client demonstration, they plan to have separate workstations connected by a router and pull the cables for a few minutes and then reconnect them.
My question is that, while keeping both app running in eclipse on my workstation, can I temporarily block them from making successful REST requests to each other and then restore the connection? As best as possible to simulate the demonstration objective of pulling the network cables.
OS X El Capitan; Eclipse Neon; Jetty 9.2.7
Self Answer:
Not as elegant as I would like, but works because the endpoints are already compile-time configurable.
Add an entry to /etc/hosts for a volatile domain pointing to 127.0.0.1
127.0.0.1 volatileDomain
Configure my endpoints to point to volatileDomain.
Start both apps.
Edit and save /etc/hosts to comment out the volatileDomain line.
Watch disconnection logic handle the current state.
Edit and save /etc/hosts to reintroduce the volatileDomain line.
Watch reconnection logic reestablish the connected state.
Related
We made a chat module in our project using socket.io. When the load is balanced and the manual deployed, if socket connections are switched to different servers, socket connections are disconnected and the messaging events are partially not processed. I solved the load balance problem with socket.io-redis library. It acts as a gateway and solves this problem thanks to redis.
Another problem is that when I deploy it manually, the pid of the servers changes and socketio connections are instantly disconnected on the client and then it is not connected even though it says connected.
Do you think that using tools such as Travis CI solves the problems in manual deploy process?
Another question is, if a system that goes to 3 servers with load balance then goes back to 2 servers, the socket connections will be closed again, what method may be required to solve this? I thought of separating the socket.io service from the monolithic structure and keeping it on a single server, and scaling the server vertically when the load increased.
We are using an Aws Elastic Beanstalk(EBS), it automatically performs load balance.
Excuse me. I speak poor English.
I am trying to create a network proxy programming with sock5 protocol. But I have no way to learn it, I can't figure out how a proxy programming works especially the followings:
What is the difference and association between socks5 and the Shadowsocks ?
Can I set a the network proxy configure in macOs instead of using swift or oc ?
such as enabling this check button(socks5 proxy) and filling the specific configure using a language instead of swift or oc:
configure
Once I set the option on macOs in the Question 2,what kind of data will the programming get if it listening the network?
e.g. will the macOs automatically forward the all new TCP connections to 127.0.0.1:1086 and automatically make the connections confirm to the socks5 request standard?
If so, why the final processing programming (transmit the datas to the real remote proxy-server) can make a successful connection? Instead of a forever loop(a.programming create a socket to remote proxy-server -> b. macOs automatically forward it to 127.0.0.1:1086 and make the connection confirm to the socks5 request standard -> a.)
Is it called as a proxy-client? or local proxy-server? what is the job of it. Why do I set a proxy address as a local one instead of a direct remote server?
Why when I setting a fake socks5 option in macOs network proxy options, a UDP programming can still work successfully?
If you can UNDERSTAND CHINESE:
Chinese language
The follow answers are based on my own experience and opinion.
1、socks5 is an Internet protocol that exchanges network packets between a client and server through a proxy server. Sockes
while Shadowsocks is a software use this protocol.
2 、Yes,you can. Install a Shaowsocks don't need any
Programming language, actually it like installing a EXE file on Windows or pkg on MacOS, it's just a software.
3、Socks5 is an Internet protocol like a language between two computer.
The software's message run on you computer will be "translated" by Shadowsocks.
Those translated message will be sent to the remote service (also run a Shadowsocks) then the service can send message to those "blocked" Webs' services.
4、The remote service can be called an proxy service.The local don't do anything except be "translated" by Shadowsocks. Look this picture.
5、The QQ don't use the port 1080, Shadowsocks need a fixed port to "translate" message.
With my limited resources and to aid debugging, I am doing local testing on a client-server (game) application by running both a server and one or more clients all on my Windows 7 dev PC. Both client and server are Java applications developed through Eclipse.
Is there any easy way to introduce lag given that everything is running on the same PC... maybe 'hack' the port used or something? Or is this only possible if each application is running on a separate PC (or separate VM)?
Make a feature in the server which makes a random lag within certain time range if detected connection comes from localhost. You can then switch this feature on/off as needed.
We have acquired a 4 channel GSM Gateway, model GoIPx4-G610 (the manual is titled "GoIP Series SIM Card for GSM Voice Gateway - GSM VOIP Gateway").
We are looking to develop a custom application to control the GOIP gateway. We have developed in the past custom applications that controlled simple GSM modems through AT commands for sending/receiving SMS messages in particular.
Although the gateway can be controlled through SIP we would like to control the GSM modems embedded in the gateway through AT commands if possible. This is because of the fine grained control AT commands offer and because we do not need VoIP features since we need only to send/receive SMS messages.
The gateway runs an unknown Linux instance to which we can connect through telnet. Unfortunately we do not have the credentials to authenticate to it. The gateway also has a web http administration interface to which we can authenticate but we can't find there settings/information related to channels that we can use for AT commands.
The documentation is very poor and the provider could not offer us any helpful information regarding this.
If anyone knows how we can send AT commands to the modems inside the gateway it is highly appreciated.
Up to now we have tried a brute force attack on the telnet interface to find the credentials with no success. We hope that once we can connect to the Linux instance driving the gateway we can connect from there to the modems through serial connections (to send AT commands) and we can reconfigure it to redirect the connections outside of the modem or to make an interface for sending commands to the modems.
The device has an update firmware option (through the web interface) which always gives the error "download failed". Downloaded the firmware (.pkg file) manually from their update pages and extracted the files from the embedded Linux distribution that should correspond to the ones placed on the gateway. The files were kept in the pkg file as an ROMFS compressed image which we mounted on a test station to see the files (probably the running OS on the gateway is an uClinux distribution).
Did this hoping that we can find there the /etc/passwd file which could be cracked with classic attack. However didn't found it and probably that file is placed on the gateway flash memory (contrary to the Linux files which are stored on the ROM memory). So if there is a way to erase / reset this flash memory that could be a solution (in case the gateway doesn't refuse to boot without those files). Another solution would be to be able to access the flash memory with the passwd file if there is such thing.
You might take the lid off and see what parts are inside.
If it's a general purpose processor with a published data sheet and without a lot of code security features, you might be in luck. For example, you might find:
By guessing headers or tracing from known pins, a console serial port, either logic level or RS232, hopefully with a shell listening
A boot mode pin for the micro connected to a resistor, which you could jumper to cause the micro to boot to a uart bootloader where you could download a new system image, or patch the existing one. If you are lucky the bootloader would be something known, like u-boot.
A JTAG port for the processor
A removable storage device which you could remove and alter
an SPI flash which you could carefully tap into and alter
A flash chip which you could desolder and transplant to a programmer
You could also make a GPL sources request for the kernel and whatever else from the vendor. Or even just trying to identify versions of things like a web server could help you look up any known exploits. Since it seems you have a similar system image to that which is installed, looking through it could be helpful - look for additional daemons running, listening on ports you weren't previously aware of, left over debug support, etc.
I am the developer of the GoIP you've purchased. Instead of trying to hack the GoIP, did you contact us to support your development of custom applications? Here are the updates of GoIP for you.
GoIP now supports SMPP. This could be an alternative to using AT commands to send and receive SMS.
API (Application Programming Interface) for GoIP is now available to support your custom application development.
If AT commands are still the preferred method, please contact us and I would be happy to discuss with you further.
Compact Framework 3.5
Windows CE 6.0 R3
Atmel-based BSP
Situation: Multiple devices from a single gateway connecting to a web service that's behind a firewall. All devices start the connection with the same IP and source port.
Problem: Basically a new device is trying to connect to the web service, firewall thinks it's the existing connection, send a RST packet. The device sequentially increments the source port, tries again. If there are 100 devices, it's a 100 RSTs in row, which takes a really long time. (see http://www.fuzeqna.com/sonicwallkb/consumer/kbdetail.asp?kbid=8013&formaction=catalert)
The solution, according to the article, is to randomize the source port. How is the source port determined and how can I set it? I'm not even sure where it's being done (CE, CF, BSP).
Edit:
Found this article about ServicePoint. ServicePoint on the HttpWebRequest class looks promising, but the spec says:
Windows Mobile for Pocket PC, Windows
Mobile for Smartphone, Windows CE
Platform Note: This property is null
until the request is sent because of
the additional network transmission
required.
Ok, so the problem appears to be in winsock.dll. What we ended up doing instantiating the Socket class and binding it to the Loopback endpoint a random number of times.