Ssh safe protocols

• cat /etc/ssh/sshd_config

Ciphers aes128-ctr,aes192-ctr,aes256-ctr
HostKeyAlgorithms ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,ssh-rsa,ssh-dss
KexAlgorithms ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group14-sha1,diffie-hellman-group-exchange-sha256
MACs hmac-sha2-256,hmac-sha2-512

check Algorithmen

• sshd -T | grep "\(ciphers\|macs\|kexalgorithms\)"

ciphers 3des-cbc,blowfish-cbc,cast128-cbc,arcfour,arcfour128,arcfour256,aes128-cbc,aes192-cbc,aes256-cbc,rijndael-cbc@lysator.liu.se,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.com,chacha20-poly1305@openssh.com
macs hmac-sha1,hmac-sha1-96,hmac-sha2-256,hmac-sha2-512,hmac-md5,hmac-md5-96,hmac-ripemd160,hmac-ripemd160@openssh.com,umac-64@openssh.com,umac-128@openssh.com,hmac-sha1-etm@openssh.com,hmac-sha1-96-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-md5-etm@openssh.com,hmac-md5-96-etm@openssh.com,hmac-ripemd160-etm@openssh.com,umac-64-etm@openssh.com,umac-128-etm@openssh.com
kexalgorithms diffie-hellman-group1-sha1,diffie-hellman-group14-sha1,diffie-hellman-group-exchange-sha1,diffie-hellman-group-exchange-sha256,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group1-sha1,curve25519-sha256@libssh.org

Bei Sicherheitsproblemen diese in die /etc/ssh/sshd_config kopieren und die unsicheren entfernen

Datei mit unsicherern Protokollen erstellen

• cat weak

 
3des-cbc
aes128-cbc
aes192-cbc
aes256-cbc
arcfour
arcfour128
arcfour256
blowfish-cbc
cast128-cbc
rijndael-cbc@lysator.liu.se

clean unsecure protocols

• /usr/local/sbin/clean-unsafe-ssh-proto.sh

#!/bin/bash
sshd -T | grep "\(ciphers\|macs\|kexalgorithms\)" > /tmp/ssh-protocols
cp /tmp/ssh-protocols /tmp/ssh-protocols.org
while read LINE
do
sed -ie "s/$LINE,//" /tmp/ssh-protocols
done < $1
cat /tmp/ssh-protocols

Ausführen

• clean-unsafe-ssh-proto.sh weak