Почти у всех устройств в cli есть telnet клиент. С помощью него можно проверить доступность сервисов HTTP, SMTP и других.
C2911-RND-INT#telnet 10.110.255.2 8080 /vrf TEST
Trying 10.110.255.2, 8080 ... Open
GET /index.htm HTTP/1.1
host: 10.110.255.2
HTTP/1.1 404 Not Found
Content-Type: text/html
Accept-Ranges: bytes
Server: HFS 2.2f
HTTP
C2911-RND-INT#telnet 10.110.255.2 8080 /vrf TEST
Trying 10.110.255.2, 8080 ... Open
GET /index.htm HTTP/1.1
host: 10.110.255.2
HTTP/1.1 404 Not Found
Content-Type: text/html
Accept-Ranges: bytes
Server: HFS 2.2f
далее идёт html код.
SMTP
telnet mail.domain.ext 25
You should receive a reply like:
Trying ???.???.???.???...
Connected to mail.domain.ext.
Escape character is '^]'.
220 mail.domain.ext ESMTP Sendmail ?version-number?; ?date+time+gmtoffset?
