# CHECK SSL CERTIFICATE INFO


It is essential to ensure that your SSL certificates are not expired or expiring soon. Neglecting this can have disastrous consequences for production systems.

Certificate files typically have a `.pem` or `.crt` extension. You can use `openssl` commands to explore the details of a certificate. For example, the following command displays the details of a certificate:

```shell
openssl x509 -in mycert.pem -text -noout
```

Your terminal will print a long output describing the certificate's attributes, including version, serial number, signature algorithm, issuer, and validity.

```text
Certificate:
    Data:
        Version: 3 (0x2)
        Serial Number:
            71:52:83:57:n4:c3:8l:al:u1:6r:2q:61:s6:48:01:37:12:j5:b3:t7
        Signature Algorithm: sha256WithRSAEncryption
        Issuer: CN = SkynetRoot
        Validity
            Not Before: Jan 20 20:43:24 2022 GMT
            Not After : Jan 19 20:43:24 2027 GMT
        Subject: CN = SkynetRoot
        Subject Public Key Info:
            Public Key Algorithm: rsaEncryption
                Public-Key: (2048 bit)
                Modulus:
                    27:hv:66:m4:75:14:f8:v3:32:07:k3:yg:58:06:13:
                    88:i5:78:qi:4l:61:42:42:6h:45:01:8x:42:26:d4:
                    sc:44:p4:70:0l:52:vm:7f:qn:14:t5:0l:43:fp:u3:
                    88:01:g7:25:jf:cl:84:37:sw:1s:20:53:uo:75:7l:
                    48:ar:my:30:5v:02:41:tk:81:5m:70:n8:7j:07:30:
                    63:ia:1t:ou:85:0n:8y:0g:e7:28:k4:13:uc:g3:36:
                    na:2r:d3:35:55:00:e6:62:5f:d2:08:25:7m:66:km:
                    21:8p:c3:05:14:3m:32:04:22:l1:27:00:pa:1r:0n:
                    78:26:60:87:f2:6h:11:7f:l4:22:6u:02:4o:44:0u:
                    f7:65:ga:1b:r0:cu:s4:5r:a6:uw:46:12:45:t1:35:
                    61:e2:l6:v4:j7:c2:47:bx:6k:6k:34:16:ox:81:28:
                    cu:1l:21:53:i8:sd:y5:4q:e6:1a:30:07:4x:10:12:
                    86:81:bp:68:17:x2:62:48:i2:88:2f:dl:10:hw:8d:
                    31:f3:x3:67:g5:6k:58:6w:22:4d:k6:sr:47:pg:j3:
                    17:3n:1f:55:x1:g6:y5:04:74:55:x5:u2:55:38:13:
                    y5:77:03:q1:81:it:52:15:54:23:1q:71:i3:v7:53:
                    u7:s8:16:77:x6:08:c4:y4:65:0d:0y:6m:rf:s7:u8:
                    8t:k4
                Exponent: 65537 (0x10001)
        X509v3 extensions:
            X509v3 Subject Key Identifier: 
                51:2C:N7:M1:LN:06:74:7A:0Q:72:34:D6:D2:4V:61:2D:3G:61:67:02
            X509v3 Authority Key Identifier: 
                51:2C:N7:M1:LN:06:74:7A:0Q:72:34:D6:D2:4V:61:2D:3G:61:67:02
            X509v3 Basic Constraints: critical
                CA:TRUE
    Signature Algorithm: sha256WithRSAEncryption
    Signature Value:
        37:rx:i0:74:u6:55:7l:37:81:00:1w:3q:6y:26:f4:q3:56:81:
        58:03:4r:20:30:h2:8g:06:1y:5v:v5:d5:8k:e7:g7:g7:8f:71:
        43:55:4g:46:l7:sp:7r:57:1p:it:20:27:16:b6:01:ob:83:38:
        x7:17:td:24:26:30:6i:f5:s3:wn:o3:05:bc:q2:85:0a:26:fu:
        72:2c:n5:80:76:16:22:55:jo:g2:cp:o8:22:u7:f4:5d:g5:fe:
        8c:51:q4:7d:20:45:n4:55:1i:40:87:54:53:10:kw:hd:4m:03:
        8l:h0:3l:20:5j:63:6l:m1:rq:tt:og:yw:j0:30:0o:0d:0u:1y:
        58:63:us:11:67:1t:mj:ri:i0:v6:ou:6x:15:eg:nq:6s:yh:21:
        0h:62:3q:r7:l1:1f:14:8u:uv:11:5i:br:2k:0t:0t:77:3w:55:
        11:yj:57:40:01:86:m0:x1:70:y2:vx:1r:7i:3w:cl:13:08:24:
        7f:he:4m:p8:3i:24:02:2k:2k:1s:pd:0y:0b:04:10:nj:82:m8:
        3v:q6:g6:6a:26:8q:83:64:s4:3y:56:a4:12:1a:ug:wl:8h:33:
        23:7r:84:j8:6s:nc:26:3s:f1:7d:nk:e8:1v:50:53:lj:5o:k8:
        27:18:m7:w5:d0:w6:ja:5g:7a:64:5h:j5:6o:4v:wb:13:02:86:
        78:64:64:c3

```

Use this command when you plan to replace or renew your SSL certificate. This will help you avoid mistakes in certificate management.