https://github.com/FiloSottile/otherport

LD_PRELOAD hack to redirect connections to other ports
https://github.com/FiloSottile/otherport

Last synced: 5 days ago
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LD_PRELOAD hack to redirect connections to other ports

• Host: GitHub
• URL: https://github.com/FiloSottile/otherport
• Owner: FiloSottile
• License: mit
• Created: 2015-12-03T14:37:58.000Z (over 8 years ago)
• Default Branch: master
• Last Pushed: 2015-12-03T16:58:50.000Z (over 8 years ago)
• Last Synced: 2024-05-01T21:38:51.777Z (about 2 months ago)
• Language: C
• Homepage:
• Size: 3.91 KB
• Stars: 42
• Watchers: 4
• Forks: 5
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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• awesome-ld-preload - otherport - redirect connections to other ports (Libraries)

README

        
# otherport

LD_PRELOAD hack to redirect connections to other ports. When started with *otherport*, binaries will believe they are connecting to OLD_PORT, while actually connecting to NEW_PORT.

Currently it rewrites only `sendto` and `recvfrom`.

## Usage

```

$ make

$ OLD_PORT=53 NEW_PORT=10053 LD_PRELOAD=$PWD/otherport.so ...

```

**Note**: all packets received on NEW_PORT will be rewritten to look like they were received from OLD_PORT, so NEW_PORT becomes effectively unusable.

## Example

For example, it lets you test DNS resolvers against servers running on high ports instead of port 53.

```

$ OLD_PORT=53 NEW_PORT=10053 LD_PRELOAD=$PWD/otherport.so unbound-host google.com

```

In this case, `unbound-host` will transparently connect to all DNS servers on the port 10053, allowing root-less tests.