[1/2] add hardened SSH client configuration
Commit Message
Introduce a custom OpenSSH client configuration file for IPFire.
Some people use it as a jumping host, so applying hardening options
system-wide improves security.
Cryptography setup is the same as for OpenSSH server configuration.
Partially fixes #11751
Signed-off-by: Peter Müller <peter.mueller@link38.eu>
---
config/ssh/ssh_config | 33 +++++++++++++++++++++++++++++++++
1 file changed, 33 insertions(+)
create mode 100644 config/ssh/ssh_config
new file mode 100644
@@ -0,0 +1,33 @@
+# OpenSSH client configuration
+#
+# set some basic hardening options for all connections
+Host *
+ # disable Roaming as it is known to be vulnerable
+ UseRoaming no
+
+ # only use secure crypto algorithm
+ KexAlgorithms curve25519-sha256@libssh.org,diffie-hellman-group-exchange-sha256
+ Ciphers chacha20-poly1305@openssh.com,aes256-gcm@openssh.com,aes128-gcm@openssh.com
+ MACs hmac-sha2-512-etm@openssh.com,hmac-sha2-256-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-512,hmac-sha2-256,umac-128@openssh.com
+
+ # always visualise server host keys (has no technical
+ # effect, but helps to identify MITM attacks)
+ VisualHostKey yes
+
+ # use SSHFP (might work on some up-to-date networks) to look up host keys
+ VerifyHostKeyDNS yes
+
+ # send keep-alive messages to connected server to avoid broken connections
+ ServerAliveInterval 10
+ ServerAliveCountMax 6
+
+ # disable X11 forwarding (security risk)
+ ForwardX11 no
+
+ # always check server IP address
+ CheckHostIP yes
+
+ # ensure only allowed authentication methods are used
+ PreferredAuthentications publickey,keyboard-interactive,password
+
+# EOF