I have two Ubuntu Server machines sitting at home. One is 192.168.1.15 (we'll call this 15), and the other is 192.168.1.25 (we'll call this 25). For some reason, when I want to setup passwordless login from 15 to 25, it works like a champ. When I repeat the steps on 25, so that 25 can login without a password on 15, no dice. I have checked both sshd_config files. Both have:

RSAAuthentication yes
PubkeyAuthentication yes

I have checked permissions on both servers:

drwx------ 2 bion2 bion2  4096 Dec  4 12:51 .ssh
-rw------- 1 bion2 bion2  398 Dec  4 13:10 authorized_keys

On 25.

drwx------  2 shimdidly shimdidly  4096 Dec  4 19:15 .ssh
-rw-------  1 shimdidly shimdidly 1018 Dec  4 18:54 authorized_keys

On 15.

I just don't understand when things would work one way and not the other. I know it's probably something obvious just staring me in the face, but for the life of me, I can't figure out what is going on. Here's what ssh -v says when I try to ssh from 25 to 15:

ssh -v -p 51337 192.168.1.15
OpenSSH_5.9p1 Debian-5ubuntu1, OpenSSL 1.0.1 14 Mar 2012
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 19: Applying options for *
debug1: Connecting to 192.168.1.15 [192.168.1.15] port 51337.
debug1: Connection established.
debug1: identity file /home/shimdidly/.ssh/id_rsa type 1
debug1: Checking blacklist file /usr/share/ssh/blacklist.RSA-2048
debug1: Checking blacklist file /etc/ssh/blacklist.RSA-2048
debug1: identity file /home/shimdidly/.ssh/id_rsa-cert type -1
debug1: identity file /home/shimdidly/.ssh/id_dsa type 2
debug1: Checking blacklist file /usr/share/ssh/blacklist.DSA-1024
debug1: Checking blacklist file /etc/ssh/blacklist.DSA-1024
debug1: identity file /home/shimdidly/.ssh/id_dsa-cert type -1
debug1: identity file /home/shimdidly/.ssh/id_ecdsa type -1
debug1: identity file /home/shimdidly/.ssh/id_ecdsa-cert type -1
debug1: Remote protocol version 2.0, remote software version OpenSSH_5.9p1 Debian-5ubuntu1
debug1: match: OpenSSH_5.9p1 Debian-5ubuntu1 pat OpenSSH*
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_5.9p1 Debian-5ubuntu1
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: server->client aes128-ctr hmac-md5 none
debug1: kex: client->server aes128-ctr hmac-md5 none
debug1: sending SSH2_MSG_KEX_ECDH_INIT
debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
debug1: Server host key: ECDSA 54:5c:60:80:74:ab:ab:31:36:a1:d3:9b:db:31:2a:ee
debug1: Host '[192.168.1.15]:51337' is known and matches the ECDSA host key.
debug1: Found key in /home/shimdidly/.ssh/known_hosts:2
debug1: ssh_ecdsa_verify: signature correct
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug1: Roaming not allowed by server
debug1: SSH2_MSG_SERVICE_REQUEST sent
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey,password
debug1: Next authentication method: publickey
debug1: Offering RSA public key: /home/shimdidly/.ssh/id_rsa
debug1: Authentications that can continue: publickey,password
debug1: Offering DSA public key: /home/shimdidly/.ssh/id_dsa
debug1: Authentications that can continue: publickey,password
debug1: Trying private key: /home/shimdidly/.ssh/id_ecdsa
debug1: Next authentication method: password