---
name: "upscli_ssl_caps"
section: "3"
platform: "linux"
package: "nut"
version: "2.8.5-2"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/upscli_ssl_caps"
---

# upscli\_ssl\_caps(3)

Report SSL capabilities of the current libupsclient build as a bitmap or string

## NAME

upscli\_ssl\_caps, upscli\_ssl\_caps\_descr - Report SSL capabilities of the current libupsclient build as a bitmap or string

## SYNOPSIS

```
        #include <upsclient.h>
        /* Header above defines bitmap values:
         * UPSCLI_SSL_CAPS_NONE         - No ability to use SSL
         * UPSCLI_SSL_CAPS_OPENSSL      - Can use OpenSSL-specific setup
         * UPSCLI_SSL_CAPS_NSS          - Can use Mozilla NSS-specific setup
         */
        int upscli_ssl_caps(void);
        const char *upscli_ssl_caps_descr(void);
```

## DESCRIPTION

The **upscli\_ssl\_caps**() function returns an int as a bitmap of SSL capability flags which may be of interest to the consumer of the [**upsclient**(3)](/upsclient/3.md) library (e.g. how to set up cryptographic material storage, and whether that should have any effect when initializing connections).

The **upscli\_ssl\_caps\_descr**() function returns a string with such information primarily intended for humans, e.g. to be used in NUT client program banners.

If there is no built-in SSL support, alternative methods like SSH tunnels or the stunnel tool can be explored.

## RETURN VALUE

The **upscli\_ssl\_caps**() function effectively returns *0* if SSL support is missing, *1* if OpenSSL can be used, or *2* if Mozilla NSS can be used, since currently the backends are exclusive and it matters because they are differently capable.

In the future it may return *-1* in the event of an error, or e.g. *3* if both OpenSSL and Mozilla NSS could be supported simultaneously (current code structure does not allow for that though).

## SEE ALSO

[**upscli\_ssl**(3)](/upscli_ssl/3.md), [**upscli\_report\_build\_details**(3)](/upscli_report_build_details/3.md)