ls -la /usr/lib/apt/methods/
mostrará os protocolos que você pode usar:
rinzwind@schijfwereld:~$ ls -la /usr/lib/apt/methods/
total 660
drwxr-xr-x 2 root root 4096 nov 18 07:03 .
drwxr-xr-x 5 root root 4096 nov 18 07:03 ..
lrwxrwxrwx 1 root root 5 okt 26 13:36 bzip2 -> store
-rwxr-xr-x 1 root root 34976 okt 26 13:36 cdrom
-rwxr-xr-x 1 root root 18592 okt 26 13:36 copy
-rwxr-xr-x 1 root root 18592 okt 26 13:36 file
-rwxr-xr-x 1 root root 88320 okt 26 13:36 ftp
-rwxr-xr-x 1 root root 55456 okt 26 13:36 gpgv
lrwxrwxrwx 1 root root 5 okt 26 13:36 gzip -> store
-rwxr-xr-x 1 root root 153768 okt 26 13:36 http
lrwxrwxrwx 1 root root 4 okt 26 13:36 https -> http
lrwxrwxrwx 1 root root 5 okt 26 13:36 lzma -> store
-rwxr-xr-x 1 root root 178344 okt 26 13:36 mirror
-rwxr-xr-x 1 root root 47264 okt 26 13:36 rred
-rwxr-xr-x 1 root root 30896 okt 26 13:36 rsh
lrwxrwxrwx 1 root root 3 okt 26 13:36 ssh -> rsh
-rwxr-xr-x 1 root root 22688 okt 26 13:36 store
lrwxrwxrwx 1 root root 5 okt 26 13:36 xz -> store
"arquivo" pode ser uma opção. Para "samba", embora isso seria: não.
Já existe um relatório de bug # 231806 sobre isso (a partir de 2008 nunca além disso que triaged).