Check if SSL CSR, Key and CRT match

To view the md5 hash of the modulus of the private key:

$ openssl rsa -noout -modulus -in mykey.key | openssl md5

To view the md5 hash of the modulus of the CSR:

$ openssl req -noout -modulus -in mycsr.csr | openssl md5

To view the md5 hash of the modulus of the certificate:

$ openssl x509 -noout -modulus -in mycert.crt | openssl md5

If all three hashes match, the CSR, certificate, and private key are compatible. You can use 

diff3

 to compare the moduli from all three files at once:

$ openssl req -noout -modulus -in mycsr.csr > csr-mod.txt

$ openssl x509 -noout -modulus -in mycert.crt > cert-mod.txt

$ openssl rsa -noout -modulus -in mykey.key > privkey-mod.txt

$ diff3 csr-mod.txt cert-mod.txt privkey-mod.txt

If all three files are identical, 

diff3

 will produce no output.