Gcr-ssh-agent causes SSH hang with ED25519 key

The surface-level problem is that git pull hangs. I found that adding IdentityAgent none to .ssh/config works around the issue (I have to type in my passphrase each time, but it doesn’t hang). So the problem is with the SSH agent provided by Gnome, gcr-ssh-agent.

If I run eval $(ssh-agent -s) to create my own instance of ssh-agent, and add my key to it, it works fine. So the problem is ONLY with gcr-ssh-agent.

Finally, if I add IdentityFile ~/.ssh/my_old_rsa_key to .ssh/config, it also works fine with gcr-ssh-agent. So it seems that gcr-ssh-agent hangs only when trying to use an ED25519 key. I don’t know when this problem started, I could swear this very setup has been working fine for a year now and I am not aware of anything related that I have changed.

If I run the underlying SSH command directly with verbose logging, it says:

USER@jelly:~/g/REPO> echo $SSH_AUTH_SOCK
/run/user/1000/gcr/ssh
USER@jelly:~/g/REPO> ssh-add -l
256 SHA256:pnTEg2/MGEoBwS76yJ0C2lDlyK5Xgn0hS5MEdl2LkcQ COMMENT (ED25519)
2048 SHA256:4ELFrWhUCq5iilesrVlhXn1UoDzHt5GGaRhk4TEKreU COMMENT (RSA)
USER@jelly:~/g/REPO> /usr/bin/ssh -vvv -o SendEnv=GIT_PROTOCOL git@git.sr.ht 'git-upload-pack '\''~USER/REPO'\'''
debug1: OpenSSH_10.0p2, OpenSSL 3.5.3 16 Sep 2025
debug3: Running on Linux 6.17.6-1-default #1 SMP PREEMPT_DYNAMIC Wed Oct 29 17:21:06 UTC 2025 (9e452b6) x86_64
debug3: Started with: /usr/bin/ssh -vvv -o SendEnv=GIT_PROTOCOL git@git.sr.ht "git-upload-pack \\'~USER/REPO\\'"
debug1: Reading configuration data /home/USER/.ssh/config
debug1: /home/USER/.ssh/config line 9: Applying options for git.sr.ht
debug1: Reading configuration data /usr/etc/ssh/ssh_config
debug3: /usr/etc/ssh/ssh_config line 30: Including file /etc/ssh/ssh_config.d/50-suse.conf depth 0
debug1: Reading configuration data /etc/ssh/ssh_config.d/50-suse.conf
debug2: checking match for 'final all' host git.sr.ht originally git.sr.ht
debug3: /etc/ssh/ssh_config.d/50-suse.conf line 3: not matched 'final'
debug2: match not found
debug3: /etc/ssh/ssh_config.d/50-suse.conf line 5: Including file /etc/crypto-policies/back-ends/openssh.config depth 1 (parse only)
debug1: Reading configuration data /etc/crypto-policies/back-ends/openssh.config
debug3: gss kex names ok: [gss-nistp256-sha256-,gss-group14-sha256-,gss-group16-sha512-]
debug3: kex names ok: [ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group14-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512]
debug3: /usr/etc/ssh/ssh_config line 31: Including file /usr/etc/ssh/ssh_config.d/20-systemd-ssh-proxy.conf depth 0
debug1: Reading configuration data /usr/etc/ssh/ssh_config.d/20-systemd-ssh-proxy.conf
debug1: /usr/etc/ssh/ssh_config line 33: Applying options for *
debug1: configuration requests final Match pass
debug1: re-parsing configuration
debug1: Reading configuration data /home/USER/.ssh/config
debug1: /home/USER/.ssh/config line 9: Applying options for git.sr.ht
debug2: add_identity_file: ignoring duplicate key ~/.ssh/USER
debug1: Reading configuration data /usr/etc/ssh/ssh_config
debug3: /usr/etc/ssh/ssh_config line 30: Including file /etc/ssh/ssh_config.d/50-suse.conf depth 0
debug1: Reading configuration data /etc/ssh/ssh_config.d/50-suse.conf
debug2: checking match for 'final all' host git.sr.ht originally git.sr.ht
debug3: /etc/ssh/ssh_config.d/50-suse.conf line 3: matched 'final'
debug2: match found
debug3: /etc/ssh/ssh_config.d/50-suse.conf line 5: Including file /etc/crypto-policies/back-ends/openssh.config depth 1
debug1: Reading configuration data /etc/crypto-policies/back-ends/openssh.config
debug3: gss kex names ok: [gss-nistp256-sha256-,gss-group14-sha256-,gss-group16-sha512-]
debug3: kex names ok: [ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group14-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512]
debug3: /usr/etc/ssh/ssh_config line 31: Including file /usr/etc/ssh/ssh_config.d/20-systemd-ssh-proxy.conf depth 0
debug1: Reading configuration data /usr/etc/ssh/ssh_config.d/20-systemd-ssh-proxy.conf
debug1: /usr/etc/ssh/ssh_config line 33: Applying options for *
debug3: expanded UserKnownHostsFile '~/.ssh/known_hosts' -> '/home/USER/.ssh/known_hosts'
debug3: expanded UserKnownHostsFile '~/.ssh/known_hosts2' -> '/home/USER/.ssh/known_hosts2'
debug2: resolving "git.sr.ht" port 22
debug3: resolve_host: lookup git.sr.ht:22
debug3: channel_clear_timeouts: clearing
debug3: ssh_connect_direct: entering
debug1: Connecting to git.sr.ht [46.23.81.155] port 22.
debug3: set_sock_tos: set socket 3 IP_TOS 0x10
debug1: Connection established.
debug1: identity file /home/USER/.ssh/USER type 3
debug1: identity file /home/USER/.ssh/USER-cert type -1
debug1: Local version string SSH-2.0-OpenSSH_10.0
debug1: Remote protocol version 2.0, remote software version OpenSSH_10.0
debug1: compat_banner: match: OpenSSH_10.0 pat OpenSSH* compat 0x04000000
debug2: fd 3 setting O_NONBLOCK
debug1: Authenticating to git.sr.ht:22 as 'git'
debug3: record_hostkey: found key type ED25519 in file /home/USER/.ssh/known_hosts:4
debug3: record_hostkey: found key type RSA in file /home/USER/.ssh/known_hosts:5
debug3: record_hostkey: found key type ECDSA in file /home/USER/.ssh/known_hosts:6
debug3: load_hostkeys_file: loaded 3 keys from git.sr.ht
debug1: load_hostkeys: fopen /home/USER/.ssh/known_hosts2: No such file or directory
debug1: load_hostkeys: fopen /etc/ssh/ssh_known_hosts: No such file or directory
debug1: load_hostkeys: fopen /etc/ssh/ssh_known_hosts2: No such file or directory
debug3: order_hostkeyalgs: have matching best-preference key type ssh-ed25519-cert-v01@openssh.com, using HostkeyAlgorithms verbatim
debug3: send packet: type 20
debug1: SSH2_MSG_KEXINIT sent
debug3: receive packet: type 20
debug1: SSH2_MSG_KEXINIT received
debug2: local client KEXINIT proposal
debug2: KEX algorithms: ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group14-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,ext-info-c,kex-strict-c-v00@openssh.com
debug2: host key algorithms: ssh-ed25519-cert-v01@openssh.com,ecdsa-sha2-nistp256-cert-v01@openssh.com,ecdsa-sha2-nistp384-cert-v01@openssh.com,ecdsa-sha2-nistp521-cert-v01@openssh.com,sk-ssh-ed25519-cert-v01@openssh.com,sk-ecdsa-sha2-nistp256-cert-v01@openssh.com,rsa-sha2-512-cert-v01@openssh.com,rsa-sha2-256-cert-v01@openssh.com,ssh-ed25519,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,sk-ssh-ed25519@openssh.com,sk-ecdsa-sha2-nistp256@openssh.com,rsa-sha2-512,rsa-sha2-256
debug2: ciphers ctos: aes256-gcm@openssh.com,aes256-ctr,aes128-gcm@openssh.com,aes128-ctr
debug2: ciphers stoc: aes256-gcm@openssh.com,aes256-ctr,aes128-gcm@openssh.com,aes128-ctr
debug2: MACs ctos: hmac-sha2-256-etm@openssh.com,hmac-sha1-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha2-256,hmac-sha1,hmac-sha2-512
debug2: MACs stoc: hmac-sha2-256-etm@openssh.com,hmac-sha1-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha2-256,hmac-sha1,hmac-sha2-512
debug2: compression ctos: none,zlib@openssh.com
debug2: compression stoc: none,zlib@openssh.com
debug2: languages ctos:
debug2: languages stoc:
debug2: first_kex_follows 0
debug2: reserved 0
debug2: peer server KEXINIT proposal
debug2: KEX algorithms: mlkem768x25519-sha256,sntrup761x25519-sha512,sntrup761x25519-sha512@openssh.com,curve25519-sha256,curve25519-sha256@libssh.org,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,ext-info-s,kex-strict-s-v00@openssh.com
debug2: host key algorithms: rsa-sha2-512,rsa-sha2-256,ecdsa-sha2-nistp256,ssh-ed25519
debug2: ciphers ctos: chacha20-poly1305@openssh.com,aes128-gcm@openssh.com,aes256-gcm@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr
debug2: ciphers stoc: chacha20-poly1305@openssh.com,aes128-gcm@openssh.com,aes256-gcm@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr
debug2: MACs ctos: umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-64@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: MACs stoc: umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-64@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: compression ctos: none,zlib@openssh.com
debug2: compression stoc: none,zlib@openssh.com
debug2: languages ctos:
debug2: languages stoc:
debug2: first_kex_follows 0
debug2: reserved 0
debug3: kex_choose_conf: will use strict KEX ordering
debug1: kex: algorithm: ecdh-sha2-nistp256
debug1: kex: host key algorithm: ssh-ed25519
debug1: kex: server->client cipher: aes256-gcm@openssh.com MAC: <implicit> compression: none
debug1: kex: client->server cipher: aes256-gcm@openssh.com MAC: <implicit> compression: none
debug1: kex: ecdh-sha2-nistp256 need=32 dh_need=32
debug1: kex: ecdh-sha2-nistp256 need=32 dh_need=32
debug3: send packet: type 30
debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
debug3: receive packet: type 31
debug1: SSH2_MSG_KEX_ECDH_REPLY received
debug1: Server host key: ssh-ed25519 SHA256:WXXNZu0YyoE3KBl5qh4GsnF1vR0NeEPYJAiPME+P09g
debug3: record_hostkey: found key type ED25519 in file /home/USER/.ssh/known_hosts:4
debug3: record_hostkey: found key type RSA in file /home/USER/.ssh/known_hosts:5
debug3: record_hostkey: found key type ECDSA in file /home/USER/.ssh/known_hosts:6
debug3: load_hostkeys_file: loaded 3 keys from git.sr.ht
debug1: load_hostkeys: fopen /home/USER/.ssh/known_hosts2: No such file or directory
debug1: load_hostkeys: fopen /etc/ssh/ssh_known_hosts: No such file or directory
debug1: load_hostkeys: fopen /etc/ssh/ssh_known_hosts2: No such file or directory
debug1: Host 'git.sr.ht' is known and matches the ED25519 host key.
debug1: Found key in /home/USER/.ssh/known_hosts:4
debug3: send packet: type 21
debug1: ssh_packet_send2_wrapped: resetting send seqnr 3
debug2: ssh_set_newkeys: mode 1
debug1: rekey out after 4294967296 blocks
debug1: SSH2_MSG_NEWKEYS sent
debug1: Sending SSH2_MSG_EXT_INFO
debug3: send packet: type 7
debug1: expecting SSH2_MSG_NEWKEYS
debug3: receive packet: type 21
debug1: ssh_packet_read_poll2: resetting read seqnr 3
debug1: SSH2_MSG_NEWKEYS received
debug2: ssh_set_newkeys: mode 0
debug1: rekey in after 4294967296 blocks
debug2: KEX algorithms: ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group14-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,ext-info-c,kex-strict-c-v00@openssh.com
debug2: host key algorithms: ssh-ed25519-cert-v01@openssh.com,ecdsa-sha2-nistp256-cert-v01@openssh.com,ecdsa-sha2-nistp384-cert-v01@openssh.com,ecdsa-sha2-nistp521-cert-v01@openssh.com,sk-ssh-ed25519-cert-v01@openssh.com,sk-ecdsa-sha2-nistp256-cert-v01@openssh.com,rsa-sha2-512-cert-v01@openssh.com,rsa-sha2-256-cert-v01@openssh.com,ssh-ed25519,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,sk-ssh-ed25519@openssh.com,sk-ecdsa-sha2-nistp256@openssh.com,rsa-sha2-512,rsa-sha2-256
debug2: ciphers ctos: aes256-gcm@openssh.com,aes256-ctr,aes128-gcm@openssh.com,aes128-ctr
debug2: ciphers stoc: aes256-gcm@openssh.com,aes256-ctr,aes128-gcm@openssh.com,aes128-ctr
debug2: MACs ctos: hmac-sha2-256-etm@openssh.com,hmac-sha1-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha2-256,hmac-sha1,hmac-sha2-512
debug2: MACs stoc: hmac-sha2-256-etm@openssh.com,hmac-sha1-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha2-256,hmac-sha1,hmac-sha2-512
debug2: compression ctos: none,zlib@openssh.com
debug2: compression stoc: none,zlib@openssh.com
debug2: languages ctos:
debug2: languages stoc:
debug2: first_kex_follows 0
debug2: reserved 0
debug3: send packet: type 5
debug3: receive packet: type 7
debug1: SSH2_MSG_EXT_INFO received
debug3: kex_input_ext_info: extension server-sig-algs
debug1: kex_ext_info_client_parse: server-sig-algs=<ssh-ed25519,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,sk-ssh-ed25519@openssh.com,sk-ecdsa-sha2-nistp256@openssh.com,rsa-sha2-512,rsa-sha2-256>
debug3: kex_input_ext_info: extension publickey-hostbound@openssh.com
debug1: kex_ext_info_check_ver: publickey-hostbound@openssh.com=<0>
debug3: kex_input_ext_info: extension ping@openssh.com
debug1: kex_ext_info_check_ver: ping@openssh.com=<0>
debug3: receive packet: type 6
debug2: service_accept: ssh-userauth
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug3: send packet: type 50
debug3: receive packet: type 7
debug1: SSH2_MSG_EXT_INFO received
debug3: kex_input_ext_info: extension server-sig-algs
debug1: kex_ext_info_client_parse: server-sig-algs=<ssh-ed25519,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,sk-ssh-ed25519@openssh.com,sk-ecdsa-sha2-nistp256@openssh.com,rsa-sha2-512,rsa-sha2-256>
debug3: receive packet: type 51
debug1: Authentications that can continue: publickey,password,keyboard-interactive
debug3: start over, passed a different list publickey,password,keyboard-interactive
debug3: preferred publickey,keyboard-interactive,password
debug3: authmethod_lookup publickey
debug3: remaining preferred: keyboard-interactive,password
debug3: authmethod_is_enabled publickey
debug1: Next authentication method: publickey
debug3: ssh_get_authentication_socket_path: path '/run/user/1000/gcr/ssh'
debug1: get_agent_identities: bound agent to hostkey
debug1: get_agent_identities: agent returned 2 keys
debug1: Will attempt key: /home/USER/.ssh/USER ED25519 SHA256:pnTEg2/MGEoBwS76yJ0C2lDlyK5Xgn0hS5MEdl2LkcQ explicit agent
debug1: Will attempt key: COMMENT RSA SHA256:4ELFrWhUCq5iilesrVlhXn1UoDzHt5GGaRhk4TEKreU agent
debug2: pubkey_prepare: done
debug1: Offering public key: /home/USER/.ssh/USER ED25519 SHA256:pnTEg2/MGEoBwS76yJ0C2lDlyK5Xgn0hS5MEdl2LkcQ explicit agent
debug3: send packet: type 50
debug2: we sent a publickey packet, wait for reply
debug3: receive packet: type 60
debug1: Server accepts key: /home/USER/.ssh/USER ED25519 SHA256:pnTEg2/MGEoBwS76yJ0C2lDlyK5Xgn0hS5MEdl2LkcQ explicit agent
debug3: sign_and_send_pubkey: using publickey-hostbound-v00@openssh.com with ED25519 SHA256:pnTEg2/MGEoBwS76yJ0C2lDlyK5Xgn0hS5MEdl2LkcQ
debug3: sign_and_send_pubkey: signing using ssh-ed25519 SHA256:pnTEg2/MGEoBwS76yJ0C2lDlyK5Xgn0hS5MEdl2LkcQ

And it hangs at that point. Oh, and there is an ssh-add process using a fair bit of CPU that never quits, a child process of gcr-ssh-agent:

USER        11014  0.1  0.0 1514564 8304 ?        SLsl 00:40   1:51  \_ /usr/libexec/gcr-ssh-agent --base-dir /run/user/1000/gcr
USER        11018  0.0  0.0  10124  7968 ?        S    00:40   0:00  |   \_ /usr/bin/ssh-agent -D -a /run/user/1000/gcr/.ssh
USER       611571 97.8  0.0  10100  8384 ?        Rs   18:23   6:24  |   \_ /usr/bin/ssh-add /home/USER/.ssh/USER

Every failed attempt to use ssh will produce another such ssh-add child proc.

This is Tumbleweed, and I just did zypper dup and rebooted yesterday.

Any ideas what’s going on? Thank you!!!

Tim

I tried examining one of the ssh-add children, and it is just repeating the following in a loop:

strace: Process 737471 attached
ioctl(0, TCGETS2, 0x7fff938f99d0)       = -1 ENOTTY (Inappropriate ioctl for device)
pipe2([4, 5], 0)                        = 0
rt_sigaction(SIGCHLD, {sa_handler=SIG_DFL, sa_mask=~[RTMIN RT_1], sa_flags=SA_RESTORER|SA_RESTART, sa_restorer=0x7fa42d242910}, {sa_handler=SIG_DFL, sa_mask=~[KILL STOP RTMIN RT_1], sa_flags=SA_RESTORER|SA_RESTART, sa_restorer=0x7fa42d242910}, 8) = 0
rt_sigprocmask(SIG_BLOCK, ~[], [], 8)   = 0
clone(child_stack=NULL, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, child_tidptr=0x7fa42dd33a10) = 737717
rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
close(5)                                = 0
read(4, "XXX My old RSA key passphrase XXX", 1023) = 33
read(4, "", 995)                        = 0
--- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=737717, si_uid=1000, si_status=0, si_utime=0, si_stime=0} ---
close(4)                                = 0
wait4(737717, [{WIFEXITED(s) && WEXITSTATUS(s) == 0}], 0, NULL) = 737717
rt_sigaction(SIGCHLD, {sa_handler=SIG_DFL, sa_mask=~[RTMIN RT_1], sa_flags=SA_RESTORER|SA_RESTART, sa_restorer=0x7fa42d242910}, {sa_handler=SIG_DFL, sa_mask=~[KILL STOP RTMIN RT_1], sa_flags=SA_RESTORER|SA_RESTART, sa_restorer=0x7fa42d242910}, 8) = 0

That doesn’t yet mean anything to me, but maybe it’s useful.

Thanks,

Tim

I removed the old RSA key file from ~/.ssh, and did systemctl --user stop gcr-ssh-agent.service. Running ssh-add -l again shows only the ED25519 key, but the ssh command still hangs just like before, and tracing ssh-add is looping identically. It’s constantly being fed the wrong passphrase for the key; maybe this has nothing to do with ED25519 vs RSA and instead is due to some weirdness in some Gnome key store?

I renamed the key file from ~/.ssh/myuser to ~/.ssh/id_ed25519, and the problem goes away. So it appears that Gnome’s key store gets confused if you move an SSH key from foo to foo_old and then create a new one called foo. That’s my best guess of what’s going on anyways. Hope it helps someone else who might find this in the future.