apt-proxy-probe.sh is a simple proxy probe script for APT. Given a plaintext list of proxy service URLs
in /etc/apt/proxies.list the script probes for available proxies at APT runtime and uses the first found. If no
configured proxy is available the probe script allows APT to transparently fall back to a direct connection to the
package repository.
This is useful if you're using a machine (laptop) that frequently switches networks or you want systems to connect reliably when a proxy service may not be 100% available. This also allows seamless failover to backup proxies in case the primary is offline.
Openbsd netcat required for ipv6 support; the script should function with traditional netcat on ipv4 only networks but
this is untested. Be aware: netcat-openbsd is the default on Ubuntu 18.04+(?), Debian defaults to netcat-traditional
as of Buster. If you have problems finding your proxies in a mixed ipv4/6 environment switch to netcat-openbsd first.
One entry per line, each is a host:port URL fragment of an apt caching proxy URL. Lines beginning with # or consisting solely of whitespace are ignored. ipv6 URLs must be bracketed per RFC2732
Examples:
# by hostname:
proxy.lan:3142
# by ipv4 address:
192.168.1.10:3142
# by ipv6 address:
[dead:beef::1]:3142
Note: If you can't prepend "http://" to the host/port URL fragment and connect to the proxy with curl your formatting is probably wrong.
First run the proxy probe script manually with bash -x /usr/local/sbin/apt-proxy-probe.sh and look for errors.
To debug problems connecting with APT edit /etc/apt/apt.conf.d/00proxy and uncomment the following lines then run
sudo apt-get update and check the debug output.
//Debug::Acquire::http "true";
//Debug::Acquire::https "true";
If you think you've found a bug please upload both the bash -x script run and the full output of APT with http(s)
debugging enabled as a gist and link them in your issue.