Does wpa_supplicant allow using all characters and symbols in SSID?

Question

I've been researching the internet to understand what characters/symbols are allowed in a 32-byte/octet SSID. From the standard (https://ieeexplore.ieee.org/document/9363693) I understand that there is no restriction on types of characters, any character can be used as first/last etc.

When I run the wpa_cli program, though, I cannot set non-ASCII letters as an SSID.

Also, I set the name of my HotSpot to include foreign characters. I see the network in the scan_results, but the wpa_supplicant FAILs to connect to the HotSpot network. (With a regular ABCxyz name, it connects OK).

There are many companies that have restrictions on the characters allowed in the SSID. Does wpa_supplicant have such restrictions?

Answer 1

wpa_supplicant.conf allows all octets, without restriction, if you enter the octets as hexadecimal. Taking examples from the example configuration file, the usual case is that the SSID is a quoted ASCII string:

# Simple case: WPA-PSK, PSK as an ASCII passphrase, allow all valid ciphers
network={
    ssid="simple"
    psk="very secret passphrase"
    priority=5
}

But if your SSID or PSK does not fit the usual case, you can give them as hex:

# Special characters in SSID, so use hex string. Default to WPA-PSK, WPA-EAP
# and all valid ciphers.
network={
    ssid=00010203
    psk=000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f
}

It seems that the same approach should work with wpa_cli.