Vim has syntax higlighting for ngnix config files. I wanted something similar for nano. There are already a few good scripts (e.g.: https://github.com/nanorc/nanorc and https://github.com/serialhex/nano-highlight) that highlight various syntaxes. This contribution works well for my needs.
Note: This normally wouldn't highlight config files in the nginx/sites-available directory, so there is a hack to make it work using top level domain extensions.
## Ngnix - The extensions default .com, etc. are useful for editing sites-available/example.tld config files, but of course are a hack.
syntax "nginx" "nginx\.conf$" "\.nginx$" "default" "\.com$" "\.net$" "\.co$" "\.org$"
## Default
color white "^.+$"
## Nginx Directives as of 2014
color yellow "((accept_mutex|accept_mutex_delay|access_log|add_after_body|add_before_body|add_header|addition_types|aio|alias|allow|ancient_browser|ancient_browser_value|auth_basic|auth_basic_user_file|auth_http|auth_http_header|auth_http_timeout|auth_request|auth_request_set|autoindex|autoindex_exact_size|autoindex_localtime|break|charset|charset_map|charset_types|chunked_transfer_encoding|client_body_buffer_size|client_body_in_file_only|client_body_in_single_buffer|client_body_temp_path|client_body_timeout|client_header_buffer_size|client_header_timeout|client_max_body_size|connection_pool_size|create_full_put_path|daemon|dav_access|dav_methods|debug_connection|debug_points|default_type|deny|directio|directio_alignment|disable_symlinks|empty_gif|env|error_log|error_page|etag|events|expires|f4f|f4f_buffer_size|fastcgi_bind|fastcgi_buffer_size|fastcgi_buffering|fastcgi_buffers|fastcgi_busy_buffers_size|fastcgi_cache|fastcgi_cache_bypass|fastcgi_cache_key|fastcgi_cache_lock|fastcgi_cache_lock_timeout|fastcgi_cache_methods|fastcgi_cache_min_uses|fastcgi_cache_path|fastcgi_cache_purge|fastcgi_cache_revalidate|fastcgi_cache_use_stale|fastcgi_cache_valid|fastcgi_catch_stderr|fastcgi_connect_timeout|fastcgi_force_ranges|fastcgi_hide_header|fastcgi_ignore_client_abort|fastcgi_ignore_headers|fastcgi_index|fastcgi_intercept_errors|fastcgi_keep_conn|fastcgi_limit_rate|fastcgi_max_temp_file_size|fastcgi_next_upstream|fastcgi_next_upstream_timeout|fastcgi_next_upstream_tries|fastcgi_no_cache|fastcgi_param|fastcgi_pass|fastcgi_pass_header|fastcgi_pass_request_body|fastcgi_pass_request_headers|fastcgi_read_timeout|fastcgi_send_lowat|fastcgi_send_timeout|fastcgi_split_path_info|fastcgi_store|fastcgi_store_access|fastcgi_temp_file_write_size|fastcgi_temp_path|flv|geo|geoip_city|geoip_country|geoip_org|geoip_proxy|geoip_proxy_recursive|gunzip|gunzip_buffers|gzip|gzip_buffers|gzip_comp_level|gzip_disable|gzip_http_version|gzip_min_length|gzip_proxied|gzip_static|gzip_types|gzip_vary|hash|health_check|hls|hls_buffers|hls_forward_args|hls_fragment|hls_mp4_buffer_size|hls_mp4_max_buffer_size|http|if|if_modified_since|ignore_invalid_headers|image_filter|image_filter_buffer|image_filter_interlace|image_filter_jpeg_quality|image_filter_sharpen|image_filter_transparency|imap_auth|imap_capabilities|imap_client_buffer|include|index|internal|ip_hash|keepalive|keepalive_disable|keepalive_requests|keepalive_timeout|large_client_header_buffers|least_conn|limit_conn|limit_conn_log_level|limit_conn_status|limit_conn_zone|limit_except|limit_rate|limit_rate_after|limit_req|limit_req_log_level|limit_req_status|limit_req_zone|limit_zone|lingering_close|lingering_time|lingering_timeout|listen|listen|location|lock_file|log_format|log_not_found|log_subrequest|mail|map|map_hash_bucket_size|map_hash_max_size|master_process|match|max_ranges|memcached_bind|memcached_buffer_size|memcached_connect_timeout|memcached_force_ranges|memcached_gzip_flag|memcached_next_upstream|memcached_next_upstream_timeout|memcached_next_upstream_tries|memcached_pass|memcached_read_timeout|memcached_send_timeout|merge_slashes|min_delete_depth|modern_browser|modern_browser_value|mp4|mp4_buffer_size|mp4_limit_rate|mp4_limit_rate_after|mp4_max_buffer_size|msie_padding|msie_refresh|multi_accept|open_file_cache|open_file_cache_errors|open_file_cache_min_uses|open_file_cache_valid|open_log_file_cache|optimize_server_names|output_buffers|override_charset|pcre_jit|perl|perl_modules|perl_require|perl_set|pid|pop3_auth|pop3_capabilities|port_in_redirect|postpone_output|protocol|proxy_bind|proxy_buffer|proxy_buffer_size|proxy_buffering|proxy_buffers|proxy_busy_buffers_size|proxy_cache|proxy_cache_bypass|proxy_cache_key|proxy_cache_lock|proxy_cache_lock_timeout|proxy_cache_methods|proxy_cache_min_uses|proxy_cache_path|proxy_cache_purge|proxy_cache_revalidate|proxy_cache_use_stale|proxy_cache_valid|proxy_connect_timeout|proxy_cookie_domain|proxy_cookie_path|proxy_force_ranges|proxy_headers_hash_bucket_size|proxy_headers_hash_max_size|proxy_hide_header|proxy_http_version|proxy_ignore_client_abort|proxy_ignore_headers|proxy_intercept_errors|proxy_limit_rate|proxy_max_temp_file_size|proxy_method|proxy_next_upstream|proxy_next_upstream_timeout|proxy_next_upstream_tries|proxy_no_cache|proxy_pass|proxy_pass_error_message|proxy_pass_header|proxy_pass_request_body|proxy_pass_request_headers|proxy_read_timeout|proxy_redirect|proxy_send_lowat|proxy_send_timeout|proxy_set_body|proxy_set_header|proxy_ssl_ciphers|proxy_ssl_crl|proxy_ssl_name|proxy_ssl_protocols|proxy_ssl_server_name|proxy_ssl_session_reuse|proxy_ssl_trusted_certificate|proxy_ssl_verify|proxy_ssl_verify_depth|proxy_store|proxy_store_access|proxy_temp_file_write_size|proxy_temp_path|proxy_timeout|queue|random_index|read_ahead|real_ip_header|real_ip_recursive|recursive_error_pages|referer_hash_bucket_size|referer_hash_max_size|request_pool_size|reset_timedout_connection|resolver|resolver|resolver_timeout|resolver_timeout|return|rewrite|rewrite_log|root|satisfy|satisfy_any|scgi_bind|scgi_buffer_size|scgi_buffering|scgi_buffers|scgi_busy_buffers_size|scgi_cache|scgi_cache_bypass|scgi_cache_key|scgi_cache_lock|scgi_cache_lock_timeout|scgi_cache_methods|scgi_cache_min_uses|scgi_cache_path|scgi_cache_purge|scgi_cache_revalidate|scgi_cache_use_stale|scgi_cache_valid|scgi_connect_timeout|scgi_force_ranges|scgi_hide_header|scgi_ignore_client_abort|scgi_ignore_headers|scgi_intercept_errors|scgi_limit_rate|scgi_max_temp_file_size|scgi_next_upstream|scgi_next_upstream_timeout|scgi_next_upstream_tries|scgi_no_cache|scgi_param|scgi_pass|scgi_pass_header|scgi_pass_request_body|scgi_pass_request_headers|scgi_read_timeout|scgi_send_timeout|scgi_store|scgi_store_access|scgi_temp_file_write_size|scgi_temp_path|secure_link|secure_link_md5|secure_link_secret|send_lowat|send_timeout|sendfile|sendfile_max_chunk|server|server|server|server_name|server_name|server_name_in_redirect|server_names_hash_bucket_size|server_names_hash_max_size|server_tokens|session_log|session_log_format|session_log_zone|set|set_real_ip_from|smtp_auth|smtp_capabilities|so_keepalive|source_charset|spdy_chunk_size|spdy_headers_comp|split_clients|ssi|ssi_last_modified|ssi_min_file_chunk|ssi_silent_errors|ssi_types|ssi_value_length|ssl|ssl|ssl_buffer_size|ssl_certificate|ssl_certificate|ssl_certificate_key|ssl_certificate_key|ssl_ciphers|ssl_ciphers|ssl_client_certificate|ssl_crl|ssl_dhparam|ssl_dhparam|ssl_ecdh_curve|ssl_ecdh_curve|ssl_engine|ssl_password_file|ssl_password_file|ssl_prefer_server_ciphers|ssl_prefer_server_ciphers|ssl_protocols|ssl_protocols|ssl_session_cache|ssl_session_cache|ssl_session_ticket_key|ssl_session_ticket_key|ssl_session_tickets|ssl_session_tickets|ssl_session_timeout|ssl_session_timeout|ssl_stapling|ssl_stapling_file|ssl_stapling_responder|ssl_stapling_verify|ssl_trusted_certificate|ssl_verify_client|ssl_verify_depth|starttls|status|status_format|status_zone|sticky|sticky_cookie_insert|stub_status|sub_filter|sub_filter_last_modified|sub_filter_once|sub_filter_types|tcp_nodelay|tcp_nopush|timeout|timer_resolution|try_files|types|types_hash_bucket_size|types_hash_max_size|underscores_in_headers|uninitialized_variable_warn|upstream|upstream_conf|use|user|userid|userid_domain|userid_expires|userid_mark|userid_name|userid_p3p|userid_path|userid_service|uwsgi_bind|uwsgi_buffer_size|uwsgi_buffering|uwsgi_buffers|uwsgi_busy_buffers_size|uwsgi_cache|uwsgi_cache_bypass|uwsgi_cache_key|uwsgi_cache_lock|uwsgi_cache_lock_timeout|uwsgi_cache_methods|uwsgi_cache_min_uses|uwsgi_cache_path|uwsgi_cache_purge|uwsgi_cache_revalidate|uwsgi_cache_use_stale|uwsgi_cache_valid|uwsgi_connect_timeout|uwsgi_force_ranges|uwsgi_hide_header|uwsgi_ignore_client_abort|uwsgi_ignore_headers|uwsgi_intercept_errors|uwsgi_limit_rate|uwsgi_max_temp_file_size|uwsgi_modifier1|uwsgi_modifier2|uwsgi_next_upstream|uwsgi_next_upstream_timeout|uwsgi_next_upstream_tries|uwsgi_no_cache|uwsgi_param|uwsgi_pass|uwsgi_pass_header|uwsgi_pass_request_body|uwsgi_pass_request_headers|uwsgi_read_timeout|uwsgi_send_timeout|uwsgi_ssl_ciphers|uwsgi_ssl_crl|uwsgi_ssl_name|uwsgi_ssl_protocols|uwsgi_ssl_server_name|uwsgi_ssl_session_reuse|uwsgi_ssl_trusted_certificate|uwsgi_ssl_verify|uwsgi_ssl_verify_depth|uwsgi_store|uwsgi_store_access|uwsgi_temp_file_write_size|uwsgi_temp_path|valid_referers|variables_hash_bucket_size|variables_hash_max_size|worker_aio_requests|worker_connections|worker_cpu_affinity|worker_priority|worker_processes|worker_rlimit_core|worker_rlimit_nofile|worker_rlimit_sigpending|working_directory|xclient|xml_entities|xslt_last_modified|xslt_param|xslt_string_param|xslt_stylesheet|xslt_types|zone)+[[:space:]])"
## Common Directives - Edit as desired
color red "((server|upstream|map|events|http)+[[:space:]])"
color yellow "((worker_processes|pid|user|worker_connections|multi_accept|default)+[[:space:]])"
color yellow "((sendfile|tcp_(nopush|nodelay)|keepalive_timeout|types_hash_max_size|server_(name|tokens|names_hash_bucket_size|name_in_redirect)|default_type)+[[:space:]])"
color yellow "((gzip|gzip_(disable|vary|proxied|comp_level|buffers|http_version|types))+[[:space:]])"
color yellow "([[:space:]]+(last|permanent))"
color yellow "((expires|allow|internal|alias|rewrite|log_not_found|access_log|include|error_(page|log)|listen|root|index|location|deny|try_files)+[[:space:]])"
color yellow "((proxy_(set_header|pass|buffering)|passenger_(root|ruby)|auth_http|(pop3|imap)_capabilities)+[[:space:]])"
color yellow "((fast_cgi_(split_path_info|pass|index|params|intercept_errors))+[[:space:]])"
color yellow "((ssl|ssl_(certificate|certificate_key|session_timeout|protocols|ciphers|prefer_server_ciphers))+[[:space:]])"
## Escapes
color red "\\[0-7][0-7]?[0-7]?|\\x[0-9a-fA-F]+|\\[bfnrt'"\?\\]"
## Comments
icolor cyan "^[[:space:]]*#.*$"
Add this to your ~/.nanorc file as an include or by cutting and pasting the text into the ~/.nanorc file.