我很高兴运行最先进的 Debian Sid 工作站。
不幸的是，我陷入了“上游回归”（network-manager-vpnc 破坏了 1.2.7 -> 1.2.8）
因此我需要“降级”到以前的版本。
我知道我应该能够通过以下方式做到这一点：
sudo apt install network-manager-vpnc=1.2.7
但这似乎对 Sid 不起作用，因为我得到：
sudo apt policy network-manager-vpnc
network-manager-vpnc:
Installed: 1.2.8-3
Candidate: 1.2.8-3
Version table:
*** 1.2.8-3 500
500 http://deb.debian.org/debian sid/main amd64 Packages
100 /var/lib/dpkg/status
这意味着只有一个版本可用，因此出现错误也就不足为奇了：
sudo apt install network-manager-vpnc=1.2.7
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
Package network-manager-vpnc is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source
E: Version '1.2.7' for 'network-manager-vpnc' was not found
我能做些什么？
更新：因为 @Stephen-Kitt 正确地指出“以前的版本”（1.2.7）从未上传到 Debian 档案，所以“解决方案”是降级到 1.2.6-3。
进入工作系统的程序（对我来说）是：
mcon@cinderella:/tmp/t$ wget http://ftp.it.debian.org/debian/pool/main/n/network-manager-vpnc/network-manager-vpnc_1.2.6-3_amd64.deb
--2022-04-28 19:34:27-- http://ftp.it.debian.org/debian/pool/main/n/network-manager-vpnc/network-manager-vpnc_1.2.6-3_amd64.deb
Resolving ftp.it.debian.org (ftp.it.debian.org)... 85.94.199.210, 2001:4b78:2000:1::1
Connecting to ftp.it.debian.org (ftp.it.debian.org)|85.94.199.210|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 125812 (123K) [application/vnd.debian.binary-package]
Saving to: ‘network-manager-vpnc_1.2.6-3_amd64.deb’
network-manager-vpnc_1.2.6-3_am 100%[====================================================>] 122.86K --.-KB/s in 0.05s
2022-04-28 19:34:27 (2.29 MB/s) - ‘network-manager-vpnc_1.2.6-3_amd64.deb’ saved [125812/125812]
mcon@cinderella:/tmp/t$ wget http://ftp.it.debian.org/debian/pool/main/n/network-manager-vpnc/network-manager-vpnc-gnome_1.2.6-3_amd64.deb
--2022-04-28 19:34:56-- http://ftp.it.debian.org/debian/pool/main/n/network-manager-vpnc/network-manager-vpnc-gnome_1.2.6-3_amd64.deb
Resolving ftp.it.debian.org (ftp.it.debian.org)... 85.94.199.210, 2001:4b78:2000:1::1
Connecting to ftp.it.debian.org (ftp.it.debian.org)|85.94.199.210|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 35592 (35K) [application/vnd.debian.binary-package]
Saving to: ‘network-manager-vpnc-gnome_1.2.6-3_amd64.deb’
network-manager-vpnc-gnome_1.2. 100%[====================================================>] 34.76K --.-KB/s in 0.02s
2022-04-28 19:34:56 (1.69 MB/s) - ‘network-manager-vpnc-gnome_1.2.6-3_amd64.deb’ saved [35592/35592]
mcon@cinderella:~$ sudo apt remove --purge network-manager-vpnc network-manager-vpnc-gnome
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
The following package was automatically installed and is no longer required:
vpnc
Use 'sudo apt autoremove' to remove it.
The following packages will be REMOVED:
network-manager-vpnc* network-manager-vpnc-gnome*
0 upgraded, 0 newly installed, 2 to remove and 0 not upgraded.
After this operation, 1,026 kB disk space will be freed.
Do you want to continue? [Y/n]
(Reading database ... 244048 files and directories currently installed.)
Removing network-manager-vpnc-gnome (1.2.8-3) ...
Removing network-manager-vpnc (1.2.8-3) ...
Processing triggers for dbus (1.14.0-1) ...
mcon@cinderella:~$ sudo dpkg -i /tmp/t/network-manager-vpnc_1.2.6-3_amd64.deb
Selecting previously unselected package network-manager-vpnc.
(Reading database ... 243969 files and directories currently installed.)
Preparing to unpack .../network-manager-vpnc_1.2.6-3_amd64.deb ...
Unpacking network-manager-vpnc (1.2.6-3) ...
Setting up network-manager-vpnc (1.2.6-3) ...
Processing triggers for dbus (1.14.0-1) ...
mcon@cinderella:~$ sudo dpkg -i /tmp/t/network-manager-vpnc-gnome_1.2.6-3_amd64.deb
Selecting previously unselected package network-manager-vpnc-gnome.
(Reading database ... 244039 files and directories currently installed.)
Preparing to unpack .../network-manager-vpnc-gnome_1.2.6-3_amd64.deb ...
Unpacking network-manager-vpnc-gnome (1.2.6-3) ...
Setting up network-manager-vpnc-gnome (1.2.6-3) ...
mcon@cinderella:~$
然后，在检查它确实有效后：
mcon@cinderella:/tmp/t$ sudo apt-mark hold network-manager-vpnc
network-manager-vpnc set on hold.
mcon@cinderella:/tmp/t$ sudo apt-mark hold network-manager-vpnc-gnome
network-manager-vpnc-gnome set on hold.
非常感谢@Stephen
答案1
如果您使用 Debian，我怀疑旧版本是 1.2.7，因为从未上传到档案馆。请注意，对于apt的=语法，您需要指定完整的包版本，例如“1.2.8-3”。
无论如何，您可以在 snapshot.debian.org 上找到过去 15 年上传到存档的软件包的所有版本；这包括network-manager-vpnc。在那里下载适当的软件包，安装它（使用dpkg -i），然后保留它（apt-mark hold network-manager-vpnc），这样它就不会再次升级。
您可以apt为特定快照配置源；看Debian 10：升级到特定次要版本 (10.10)了解详情。您可能还会发现为什么以前版本的 Debian 软件包会在软件包存储库中消失？ （与版本控制系统配置高度相关）相关的。
还请提交一个错误 ( reportbug network-manager-vpnc)，以便其他人能够了解该回归并希望它能够得到修复。