Completes the Turkish translation of six more modules and removes their
machine-generated lang/tr.auto files:
cluster-useradmin 154 strings - users and groups across servers
net 146 new strings - IPv6, bridges, bonding, VLANs
pptp-server 141 strings - PoPToP PPTP VPN server
format 141 strings - Solaris disk partitioning
filter 131 strings - Usermin mail filtering and autoreply
fetchmail 130 strings - Fetchmail mail retrieval
net already had a partial lang/tr; the 196 existing strings were kept
and only the untranslated remainder was added.
Interface and driver terminology that appears verbatim in configuration
files (Netplan, dhcpcd, Network Manager, miimon, updelay, downdelay,
balance-tlb, balance-alb, VLAN, PPP, PAP, CHAP, MS-CHAP, MPPE, PTY,
UFS, INBOX, procmail) is kept in English.
ⓘ Treat Linux active virtual interfaces as secondary IP addresses instead of independent links, fixing alias parsing, hiding invalid status controls, rejecting down-state creation, and removing existing aliases with ip addr del when needed.
Reproduce path:
Example repro before this fix:
1. Go to **Network Configuration → Network Interfaces → Active Now**.
2. Click **Add a new interface**.
3. Enter:
```text
Name: enp0s5:1
IPv4 address: 10.211.55.21
Netmask: 255.255.255.0
Status: Down
```
4. Click **Create**.
Before the fix, Webmin could still create the alias or handle it inconsistently, because `enp0s5:1` is not a real link that can be “down”. It is just an extra IP address on `enp0s5`.
Expected after the fix:
- The UI should not offer `Status` for active virtual aliases.
- If someone submits `up=0` manually anyway, Webmin rejects it with:
`Virtual interfaces cannot be created with down status`
- If an existing active virtual alias is saved as down through lower-level code, Webmin removes the IP using something like:
```bash
ip addr del 10.211.55.21/24 dev enp0s5
```
This PR adds dhcpcd backend support for Debian and Raspberry Pi OS network configuration. It detects dhcpcd only as a final fallback after Netplan, NetworkManager, and ifupdown, preventing Webmin from incorrectly falling back to `/etc/network/interfaces` on dhcpcd-managed systems.
The new backend reads and writes `/etc/dhcpcd.conf`, including DHCP and static IPv4/IPv6 configuration, gateways, static routes, DNS servers, search domains, MTU, and virtual IPv4 aliases. It also supports implicit DHCP-managed interfaces for default dhcpcd setups with no explicit interface blocks, and handles `allowinterfaces` / `denyinterfaces` behavior.
This PR also fixes apply/delete flows for dhcpcd-managed interfaces and virtual aliases, avoids rewriting generated `/etc/resolv.conf`, preserves spacing/comments in touched hosts and nsswitch files, and tightens Active Now handling so virtual aliases are treated as IP addresses rather than independent links.
https://github.com/webmin/webmin/issues/1607
* Note: Preserve existing Netplan indentation when updating DNS settings, validate with netplan generate before applying, and surface apply errors to avoid network loss from malformed YAML.
